Lenz heated socks: the only honest runtime table in this category, and the one number they will not give you
Every other maker publishes a single runtime and hopes. Lenz publishes a range, for four battery sizes, split by whether you are heating feet or a torso. Then it declines to tell you the voltage, which makes the watt-hour conversion this whole site runs on impossible.
By Scooter M. · Published September 21, 2026
How this is funded: buy links here are tagged and earn us a commission at no extra cost to you. It does not affect what we recommend, and we take no free product and no sponsorship. Read the disclosure.
Lenz publishes the best runtime disclosure in heated apparel: a full matrix of four battery sizes against two garment classes against three heat levels, with every single entry given as a range rather than a flattering single number. It also publishes no voltage, no capacity beyond the number in the pack's name, and no watt-hours — so the energy conversion every other page on this site performs is impossible here. Those two facts are the whole Lenz decision.
What Lenz actually publishes
Here is the socks half of the table, in Lenz's own figures:
| Battery | Level 1 | Level 2 | Level 3 (highest) |
|---|---|---|---|
| Lithium Pack rcB 2000 | 18.5-23.0 h | 10.5-12.5 h | 6.5-7.5 h |
| Lithium Pack rcB 1800 | 16.0-20.0 h | 9.0-11.0 h | 5.5-6.5 h |
| Lithium Pack rcB 1400 | 12.5-16.5 h | 6.5-8.5 h | 4.5-5.5 h |
| Lithium Pack rcB 1200 | 10.0-14.0 h | 5.5-7.5 h | 3.5-4.5 h |
| Heat Pack / Heat Pack 2.0 | 9.0-13.0 h | 4.5-6.5 h | 3.0-4.0 h |
And a second table, same shape, for gloves, vests, pants, jackets and pads. Nobody else in this category publishes anything remotely like this.
Quick picks
Tap any row to jump to the full write-up below. The energy column is the pack’s capacity times its voltage — the number this category does not print.
| # | Product | Best for | Energy | Price |
|---|---|---|---|---|
| 1 |  Lenz Heat Sock 5.1 Toe Cap Slim Fit with rcB 1400 BatteriesA thin merino-and-silk sock built for a tight boot, sold with the packs, and backed by the only runtime table in this … | Ski boots, and the best runtime disclosure in the category | — | $449.95View on Amazon |
| 2 |  Lenz Heat Sock 6.1 Toe Cap Merino Compression with rcB 1400 Batteries35% merino in a compression knit thin enough for a race boot, and the same class-leading runtime table — but Lenz neve… | A compression knit with heat — as long as you read the caveat | — | $449.95View on Amazon |
| 3 |  Lenz Heat Socks 4.1 Toe Cap (Socks Only)A legitimate purchase at a fraction of the set price — and a trap for anyone who does not notice the words "Socks Only… | Replacing worn socks when you already own the packs | — | $130.00View on Amazon |
| 4 |  Lenz Lithium Pack rcB 1800Lenz's published table puts this pack at 16-20 hours on level 1 and 5.5-6.5 on level 3 with socks — around 28% more ti… | Buying back the hours a smaller pack costs you | — | $499.77View on Amazon |
#ad — buy links are tagged and earn us a commission at no extra cost to you. Prices come from a live feed; where none is available the button reads “Check price” rather than showing a number we cannot stand behind. How we are funded.
Lenz Heat Sock 5.1 Toe Cap Slim Fit with rcB 1400 Batteries
A thin merino-and-silk sock built for a tight boot, sold with the packs, and backed by the only runtime table in this category that gives you a range instead of a single flattering number.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Energy
- Not derivable — Lenz publishes no voltage or Wh
- Composition
- 30% polyester, 25% merino, 20% polyamide, 15% polyacrylic, 5% silk, 5% elastane
- Runtime given as
- A range at every level — 4.5-5.5 h at level 3
- Sizing
- EU 31-34 through 45-47
- Heat zones
- Toe Cap element heating the toes from above and below, per Lenz
- Settings
- Three levels on the pack itself, or stepless adjustment over Bluetooth in the free Lenz Heat app
- Care
- Washable at 30°C in the washing machine using the included laundry bag; air dry, no fabric softener, no tumble drying, per Lenz
On wattage: Not published, and unlike every other product here we cannot derive it either — that takes watt-hours, and Lenz publishes none. The hours above are the CONSERVATIVE end of Lenz's published ranges (level 3 is stated as 4.5-5.5 h, level 2 as 6.5-8.5 h, level 1 as 12.5-16.5 h). We quote the low end deliberately; the high end is theirs to claim.
On the pack: Lenz publishes NO voltage, milliamp-hour or watt-hour figure for the rcB packs — the pack name is the only capacity hint you get, and a name is not a specification. This is the one garment family on the site where we cannot do the watt-hour conversion, because the maker withholds the one number it needs. What Lenz gives instead is far better than most: a runtime matrix covering four pack sizes, two garment classes and three heat levels, every entry a range.
What we like
- The only maker on this site that publishes runtime as a RANGE, which is what a runtime actually is
- Runtimes are given separately for socks and for gloves/vests/jackets — a distinction nobody else makes
- Slim fit is genuinely thin enough for a race or performance boot, where most heated socks are not
- Stepless app control rather than three fixed steps, which matters when the setting you want is between two of them
What we do not
- No voltage, no milliamp-hours, no watt-hours anywhere — the conversion this whole site runs on is impossible here
- Among the most expensive heated socks sold, by a wide margin
- The rcB 1400 packs in the box are not the packs Lenz currently sells on its own store, which complicates buying spares
- Only the toes are heated — nothing for the arch or the heel
Who this suits
A skier with a tight boot who has already decided that cold toes are worth solving properly, and who values a maker that publishes an honest range.
Who should skip it
You want to know the watt-hours. Lenz will not tell you, and no amount of arithmetic gets round a missing voltage.
Spec sources: Lenz — Heat Sock 5.1 Toe Cap (30% polyester, 25% merino wool, 20% polyamide, 15% polyacrylic, 5% silk, 5% elastane; Toe Cap heating element heats the toes from above and below; runs on all Body Heat System lithium packs; washable at 30°C with the included laundry bag; EU 31-34 to 45-47) · Lenz — Heat Sock 5.1 Toe Cap Slim Fit · Lenz — Heating time & battery life (full runtime matrix: rcB 2000 / 1800 / 1400 / 1200 and Heat Pack, each given as a RANGE per heat level, listed separately for Heat Socks and for Heat Gloves/Vest/Pants/Jacket/Pads) · Lenz — Lithium Pack rcB 1200 (USB) (85 grams, 8.5 x 5.5 x 1 cm; socks 10.0-14.0 h / 5.5-7.5 h / 3.5-4.5 h, gloves-vest-pants-jacket 5.5-7.5 h / 3.0-4.0 h / 2.0-2.5 h; stepless heat via Bluetooth app or 3 levels on the pack; no voltage, mAh or Wh published) · Lenz — Lenz Heat App FAQ ("'HeatSync' allows you to set the heat level from 1 to 9 or turn off the lithium pack"; "It is also possible to control the left and right lithium packs separately with 'HeatLeft | Right'"; repeating interval function; free on the Apple App Store or Google Play; "Android version from or iOS from 11.0" and "Bluetooth 4.0 (SMART compatible)"; "Most smartphone manufacturers allow a maximum number of 6 to 10 simultaneously paired devices. If you exceed this number, you will not be able to connect the lithium pack.")
Lenz Heat Sock 6.1 Toe Cap Merino Compression with rcB 1400 Batteries
35% merino in a compression knit thin enough for a race boot, and the same class-leading runtime table — but Lenz never publishes a pressure figure, so treat "compression" as a fit description rather than a medical claim.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Energy
- Not derivable — Lenz publishes no voltage or Wh
- Composition
- 55% polyamide, 35% merino wool, 10% elastane
- Compression pressure
- Not published — no mmHg figure anywhere
- Sizing
- EU 31-34 through 45-47
- Heat zones
- Toe Cap element heating the toes from above and below, per Lenz
- Settings
- Three levels on the pack, or stepless over Bluetooth in the Lenz Heat app
- Care
- Washable at 30°C in the washing machine, per Lenz
On wattage: Not published and not derivable. Worth noting what Lenz's matrix does imply: at every pack size, socks run roughly 1.85 times as long as gloves, vests, pants or jackets on the same pack and the same level. Foot heating is a far smaller electrical load than torso heating, and Lenz's numbers are consistent about it across all four pack sizes — which is itself a sign the table was calculated rather than invented.
On the pack: Runs on any Lenz Body Heat System pack, which clips to the sock cuff with snap buttons. As with every Lenz product, no voltage, mAh or Wh is published, so no watt-hour figure can be given honestly.
What we like
- 35% merino is a high wool content for a sock this thin
- Compression knit plus a toe heater in one garment, which very few makers attempt
- Backed by the same published runtime matrix — ranges, per pack, per garment class, per level
- Anatomically shaped with protectors at the toe and heel, aimed squarely at race boots
What we do not
- No mmHg pressure figure is published, so this is not a graduated medical compression sock and should not be bought as one
- No voltage, mAh or Wh — the same disclosure gap across the whole Lenz line
- A very tight fit by design, which is uncomfortable if you are not putting it in a boot
- Expensive, and the packs it ships with are no longer the ones Lenz sells directly
Who this suits
A racer or hard skier who wants compression and toe heat in a single thin layer and is not relying on it for a circulatory condition.
Who should skip it
A clinician told you to wear compression. Without a published pressure rating this cannot fill that prescription — see [heated socks for neuropathy](/heated-socks/for-neuropathy) for what to ask instead.
Spec sources: Lenz — Heat Socks 6.1 Toe Cap Merino Compression (55% polyamide, 35% merino wool, 10% elastane; Toe Cap heating element; compression knit, no mmHg figure published; runs on all Body Heat System lithium packs; washable at 30°C; EU 31-34 to 45-47) · Lenz — Heating time & battery life (full runtime matrix: rcB 2000 / 1800 / 1400 / 1200 and Heat Pack, each given as a RANGE per heat level, listed separately for Heat Socks and for Heat Gloves/Vest/Pants/Jacket/Pads) · Lenz — Lithium Pack rcB 1200 (USB) (85 grams, 8.5 x 5.5 x 1 cm; socks 10.0-14.0 h / 5.5-7.5 h / 3.5-4.5 h, gloves-vest-pants-jacket 5.5-7.5 h / 3.0-4.0 h / 2.0-2.5 h; stepless heat via Bluetooth app or 3 levels on the pack; no voltage, mAh or Wh published) · Lenz — Lenz Heat App FAQ ("'HeatSync' allows you to set the heat level from 1 to 9 or turn off the lithium pack"; "It is also possible to control the left and right lithium packs separately with 'HeatLeft | Right'"; repeating interval function; free on the Apple App Store or Google Play; "Android version from or iOS from 11.0" and "Bluetooth 4.0 (SMART compatible)"; "Most smartphone manufacturers allow a maximum number of 6 to 10 simultaneously paired devices. If you exceed this number, you will not be able to connect the lithium pack.")
Lenz Heat Socks 4.1 Toe Cap (Socks Only)
A legitimate purchase at a fraction of the set price — and a trap for anyone who does not notice the words "Socks Only" at the end of the title. No batteries are included.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Batteries included
- NO — socks only
- Energy
- Depends entirely on which pack you own
- Takes
- Any Lenz Body Heat System pack
- Sizing
- EU 31-34 through 45-47
- Heat zones
- Toe Cap element, per Lenz
- Settings
- Three levels on the pack, or stepless over Bluetooth
- Care
- Washable at 30°C in the washing machine, per Lenz
On wattage: Not published and not derivable. The hours above are the low end of Lenz's published ranges on the smallest current pack; a larger pack moves every figure up in proportion, roughly linearly with the number in the pack's name.
On the pack: There is no battery in this box. It takes any Lenz Body Heat System lithium pack, which you must already own or buy separately — and a pair of Lenz packs costs considerably more than these socks do.
What we like
- A fraction of the price of a full set, which is exactly right if the packs you own still hold charge
- Extends the life of an expensive system rather than replacing it
- Compatible with every Lenz pack, including ones no longer sold
- The sensible way to own two pairs for alternate days
What we do not
- No batteries, and the listing title is the only place that says so clearly
- Useless as a first purchase — the packs cost several times what the socks do
- The 4.1 is an older model than the 5.1 and 6.1
- Same disclosure gap as the rest of the line: no voltage, no watt-hours
Who this suits
An existing Lenz owner whose socks have worn out before their batteries did.
Who should skip it
This would be your first Lenz purchase. You will receive socks that cannot heat, and the cheapest fix costs more than the socks did.
Spec sources: Lenz — Heat Socks 4.1 Toe Cap · Lenz — Heating time & battery life (full runtime matrix: rcB 2000 / 1800 / 1400 / 1200 and Heat Pack, each given as a RANGE per heat level, listed separately for Heat Socks and for Heat Gloves/Vest/Pants/Jacket/Pads)
Lenz Lithium Pack rcB 1800
Lenz's published table puts this pack at 16-20 hours on level 1 and 5.5-6.5 on level 3 with socks — around 28% more time than the rcB 1400 that ships in the sets, for a price that is not 28% higher.
#ad Price as of October 17, 2026. How we are funded.
The numbers
- Energy
- Not derivable — Lenz publishes no voltage or Wh
- Socks, level 1
- 16.0-20.0 h per Lenz's table
- Torso garments, level 1
- 9.0-11.0 h per Lenz's table
- Availability note
- Not currently listed on Lenz's own store
- Heat zones
- Not applicable — this is a battery
- Settings
- Three levels on the pack, or stepless over Bluetooth in the Lenz Heat app
- Care
- Remove before washing the garment
On wattage: Not published and not derivable. One honest observation from the table: Lenz's bigger packs claim slightly MORE hours per unit of named capacity than the smaller ones — roughly 11% more from the rcB 1200 to the rcB 2000. That is a small thumb on the scale in favour of the expensive packs, and worth knowing before you assume the scaling is exactly linear.
On the pack: Even on the pack's own listing, Lenz publishes no voltage, no milliamp-hour figure beyond the name, and no watt-hours. The number in the name is the only capacity signal, and the runtime table is the only performance data.
What we like
- About 28% more claimed time than the rcB 1400 that comes in the sets
- Works across the whole Body Heat System — socks, gloves, vest, pants, jacket and pads
- Still fully covered by Lenz's published runtime matrix
- Bluetooth and app control, same as the current packs
What we do not
- When we checked, Lenz's own store listed the rcB 2000, rcB 1200 and Heat Pack 2.0 — the 1800 and 1400 pages redirected to the battery collection
- No voltage, mAh or Wh published, on a product whose entire purpose is storing energy
- Priced like a premium accessory rather than a spare
- Bigger packs claim slightly better hours-per-capacity than the small ones, so the scaling flatters them a little
Who this suits
A Lenz owner who has decided the pack, not the sock, is what limits their day.
Who should skip it
You have not yet bought the socks. Start with a set, find out whether the included packs actually run short, and only then pay for more.
Spec sources: Lenz — Heating time & battery life (full runtime matrix: rcB 2000 / 1800 / 1400 / 1200 and Heat Pack, each given as a RANGE per heat level, listed separately for Heat Socks and for Heat Gloves/Vest/Pants/Jacket/Pads) · Lenz — Lithium Pack rcB 1200 (USB) (85 grams, 8.5 x 5.5 x 1 cm; socks 10.0-14.0 h / 5.5-7.5 h / 3.5-4.5 h, gloves-vest-pants-jacket 5.5-7.5 h / 3.0-4.0 h / 2.0-2.5 h; stepless heat via Bluetooth app or 3 levels on the pack; no voltage, mAh or Wh published)
We checked whether the table is real
A beautiful table is easy to invent. So we tested it two ways.
Test one: do socks and torso garments scale sensibly?
Lenz gives separate figures for socks and for gloves/vest/pants/jacket/pads. Dividing one by the other at level 1:
- rcB 2000: 18.5 h socks against 10.0 h torso — 1.85x
- rcB 1800: 16.0 against 9.0 — 1.78x
- rcB 1400: 12.5 against 6.5 — 1.92x
- rcB 1200: 10.0 against 5.5 — 1.82x
A consistent ratio of roughly 1.85 across four independent pack sizes. Heating two toe caps is a far smaller electrical load than heating a torso, and Lenz's numbers agree with themselves about exactly how much smaller. That is what a calculated table looks like. A copied one would have drifted.
Test two: do the packs scale with their names?
Here the table flatters the expensive packs slightly. Taking the low end of level 1 for socks and dividing by the number in the pack's name gives hours per 100 units of named capacity: 0.83 for the rcB 1200, 0.89 for the 1400, 0.89 for the 1800, 0.93 for the 2000.
So the biggest pack claims about 11% more time per unit of capacity than the smallest. That is not damning — bigger cells really do discharge a little more efficiently — but it does mean the rcB 2000 is not simply 67% more pack than the rcB 1200. Budget for slightly less than the names imply.
And now the hole in it
Every other product on this site gets a watt-hour figure, because watt-hours are the only unit that lets you put a DEWALT tool battery, a 7.4 V apparel pack and a USB power bank on the same axis. Lenz gets none.
- No voltage on the pack pages, the sock pages or the runtime page.
- No milliamp-hour figure beyond the number in the model name, which is a name and not a specification.
- No watt-hours anywhere.
We could guess. A single-cell lithium pack at the usual 3.7 V nominal would put an rcB 1200 near 4.4 Wh. But that is our inference from a convention, not a Lenz figure, and this site does not publish inferences as specifications. So the watt-hour column on the Lenz products above reads Not derivable, and it will keep reading that until Lenz prints a voltage.
Which Lenz
A tight ski or race boot
The 5.1 Slim Fit. Merino and silk, genuinely thin, and the Toe Cap element heats the toes from above and below rather than just underneath. This is the use case Lenz was built for and the reason people pay what they pay.
You want compression as well
The 6.1 Merino Compression — 35% merino in a compression knit, anatomically shaped with toe and heel protectors. Buy it for the fit in a race boot. Do not buy it as a medical compression garment; there is no published pressure figure.
You already own the packs
The 4.1 socks-only listing, at a fraction of the set price. This is the right purchase when the socks have worn out before the batteries have, and it is exactly the wrong purchase if it would be your first.
The socks are fine, the day is too long
The bigger pack. Lenz's table says an rcB 1800 buys about 28% more time than the rcB 1400 in the sets. Note the availability caveat in the skip list before you commit to that model specifically.
How the disclosure compares
| Brand | Watt-hours | Runtime detail | Temperatures |
|---|---|---|---|
| Lenz | Never | Matrix of ranges, by pack and garment class | Never |
| Gobi Heat | On both packs | One line-wide figure for every garment | Sahara II only |
| Fieldsheer | Never | Per garment, four settings, scales with zones | Every garment |
| ActionHeat | Never (derivable) | Three settings, reconciles with the output ceiling | Every setting |
Nobody does all three. Lenz is at the top of one column and the bottom of another, which is the fairest summary of the brand we can give.
What we would skip, and why
- Any listing ending in "Socks Only"
- Lenz sells its socks both as sets with the lithium packs and as socks alone, and the difference is three words at the end of a long title. The socks-only version is a perfectly good purchase for an existing owner and a useless one for a first-time buyer, because a pair of Lenz packs costs several times what the socks do. We have listed one on this page precisely so the distinction is visible.
- Buying the compression version for a medical reason
- Lenz calls the 6.1 a compression sock and never publishes a pressure figure — no mmHg anywhere on the product page. Without a stated pressure it is a tight athletic knit, not graduated medical compression, and it cannot fill a prescription. Heated socks for neuropathy covers what to ask for instead.
- Assuming the pack in the box is one you can rebuy
- The Amazon sets ship rcB 1400 packs. When we checked, Lenz's own store was selling the rcB 2000, the rcB 1200 and the Heat Pack 2.0 — the rcB 1400 and rcB 1800 URLs both redirected to the battery collection page. They remain in the published runtime table and remain compatible, but plan your spares around what Lenz is currently selling.
- Lenz at all, if you want to compare it on watt-hours
- You cannot. Lenz publishes no voltage, no milliamp-hour figure beyond the number in the pack's name, and no watt-hours. Every other product on this site can be reduced to a Wh figure and lined up against the rest. Lenz cannot, and that is a real cost of buying into the system.
Our criteria, and what we did not do
- Runtime figures quoted at the CONSERVATIVE end of Lenz's published ranges. Where Lenz says 4.5-5.5 hours, we record 4.5. The optimistic end is theirs to claim.
- No watt-hour figures anywhere on this page, because Lenz publishes no voltage and we will not invent one.
- The published matrix cross-checked for internal consistency — sock-to-torso ratios and pack-to-pack scaling both tested.
- Availability of every pack checked against Lenz's own store, not just the retailer listing.
- We have not worn any of these. How we work.
We have not worn, tested or owned any of these products, and we say so on every page rather than in a footer. What we do instead is compile the published specifications and do the arithmetic. The full method.
Frequently asked
- How long do Lenz heated socks last on a charge?
- It depends on the pack and the level, and Lenz publishes the full table. With the rcB 1400 packs that ship in most sets: 12.5-16.5 hours at level 1, 6.5-8.5 at level 2 and 4.5-5.5 at level 3. The rcB 2000 raises those to 18.5-23.0, 10.5-12.5 and 6.5-7.5.
- What voltage are Lenz lithium packs?
- Lenz does not publish it — not on the pack pages, not on the sock pages, not on the runtime page. It also publishes no watt-hour figure and no milliamp-hour figure beyond the number in the model name. It is the one brand on this site whose energy we cannot convert.
- Are Lenz heated socks worth the money?
- They are among the most expensive heated socks sold. What you are buying is a genuinely thin sock that fits a race boot, a toe element that heats from above and below, stepless app control, and the most honest runtime disclosure in the category. What you are not buying is any way to compare the batteries with anyone else's.
- Is the Lenz 6.1 a real compression sock?
- It is a compression knit, and Lenz describes it as anatomically tight with toe and heel protectors. But no pressure figure in mmHg is published anywhere, so it is not graduated medical compression and should not be bought to fill a clinical recommendation.
- Can I use any battery with Lenz socks?
- Only Lenz Body Heat System packs, which clip to the sock cuff with snap buttons. Because no voltage or capacity is published, there is no way to identify a third-party equivalent, which effectively locks you to Lenz for spares.
- Can you machine wash Lenz heated socks?
- Yes — Lenz says 30°C in the machine using the included laundry bag, then air dry, with no fabric softener and no tumble drying. The battery comes off first. Washing heated clothing has the general rules.
Sources
- Lenz — Heating time & battery life (the full runtime matrix: rcB 2000 / 1800 / 1400 / 1200 and Heat Pack, every figure a range, listed separately for Heat Socks and for Heat Gloves/Vest/Pants/Jacket/Pads, plus Heat Sole)
- Lenz — Lithium Pack rcB 1200 (USB) (85 g; 8.5 x 5.5 x 1 cm; stepless heat over Bluetooth or 3 levels on the pack; no voltage, mAh or Wh published)
- Lenz — Heat Sock 5.1 Toe Cap (30% polyester, 25% merino, 20% polyamide, 15% polyacrylic, 5% silk, 5% elastane; Toe Cap element heats from above and below; washable at 30°C; EU 31-34 to 45-47)
- Lenz — Heat Socks 6.1 Toe Cap Merino Compression (55% polyamide, 35% merino, 10% elastane; compression pressure NOT published)
- Lenz — Heat Socks 4.1 Toe Cap
Related
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