Our Warmth System

What Is a TOG Rating?

You've seen "7× warmer" on the packaging. Here's what that number actually means, and why we're the only sock brand that publishes it.

2.3
TOG: our highest-rated sock
7×
warmer than cotton
3
warmth levels to choose from
The Science

TOG measures how well a fabric holds your body heat

TOG stands for Thermal Overall Grade. It measures thermal resistance: how effectively a fabric prevents your body heat from escaping through it. Higher TOG, more heat retained, warmer feet.

Your body produces heat. A sock sits between your skin and the outside air. A low-TOG sock lets heat pass through quickly. A high-TOG sock slows that transfer. Your body warmth stays where you need it.

TOG is not a marketing term. It's a textile industry standard. Researchers F. T. Peirce and W. H. Rees developed it in the 1940s at the Shirley Institute in Manchester, England, the research arm of the British Cotton Industry Research Association. Their paper, "The Transmission of Heat Through Textile Fabrics," was published in the Journal of the Textile Institute Transactions in 1946. The testing method they built (a controlled heat source and calibrated plates measuring heat flow through a fabric sample) became the basis for BS 4745, the British Standard for thermal resistance of textiles. It remains the international testing standard today.

Heat Holders tests every sock tier against this standard. The number on the packaging is a lab result, not an estimate.

Why this matters: Most sock brands don't publish a TOG rating at all. Heat Holders is the only major thermal sock brand that tests to BS 4745 and prints the result on every package. A TOG number on Heat Holders socks means that product was tested in a lab, against a recognized standard, and the result was published for you to compare.

Why we measure against cotton, and why cotton loses

Every "× warmer" figure in the Heat Holders range is measured against a standard cotton sock at 0.3 TOG. Cotton is the baseline because it's what most people are wearing when their feet get cold. It's also the reason their feet are cold.

Cotton absorbs moisture. When your feet sweat (and they do, even at rest, even in winter) cotton holds that moisture against your skin. Wet fabric conducts heat away from your body faster than dry fabric. A cotton sock starts at a low TOG rating and gets worse as you wear it, because it traps the moisture your feet produce and turns it into a cooling mechanism.

This is why "just wear thicker socks" fails if those socks are cotton. A thick cotton sock absorbs more moisture. More moisture, faster heat loss. The sock feels thick, but it's working against you.

Heat Holders' thermal yarn manages moisture differently. The yarn doesn't absorb moisture the way cotton does. The brushed inner pile creates a layer of trapped air, not trapped moisture, against your skin. Trapped air is the insulation. The "7× warmer" figure is the measured difference between a fabric that holds warm air close to your skin and a fabric that holds moisture against it.

Our Warmth Levels

Three tiers, one system: ORIGINAL, LITE, and ULTRA LITE

Each tier is lab-tested. Each has a published TOG rating. Each is designed for different situations. The warmth system is not about better or worse. It's about matching the right level of thermal protection to how and where you wear your socks.

TierTOG Ratingvs CottonBest For
ORIGINAL™2.3 TOG7× warmerAt home, outdoors standing still, maximum warmth
LITE™1.6 TOG5× warmerIn boots, casual shoes, everyday cold
ULTRA LITE™1.0 TOG3× warmerDress shoes, work shoes, thinnest profile
Standard cotton sock0.3 TOG1× (baseline)
2.3TOG
7×
warmer than cotton

ORIGINAL™

At homeOutdoorsCold floorsMaximum warmth

The flagship. Thickest construction in the range, with the longest loop pile for maximum heat retention. For people whose feet are genuinely cold: at home, on the sidelines, anywhere you're not generating body heat through movement.

Shop ORIGINAL Socks
1.6TOG
5×
warmer than cotton

LITE™

In bootsCasual shoesWalkingEveryday cold

Medium-weight warmth. Shorter loop pile, thinner sock. Fits inside boots and casual shoes without squeezing. Five times warmer than cotton, with a profile that works all day in shoes.

Shop LITE Socks
1.0TOG
3×
warmer than cotton

ULTRA LITE™

Dress shoesWork shoesThinnest profileYear-round

Thinnest construction in the range. Still three times the thermal resistance of cotton. For shoes where bulk is a problem. Not a compromise tier. A different tier for a different problem.

Shop ULTRA LITE Socks
2.3TOG

WORXX™

ORIGINAL-level warmth (2.3 TOG, 7×) with reinforced durability for physical work environments.

Shop WORXX →
2.3TOG

Slipper Socks

ORIGINAL-level warmth (2.3 TOG) with non-slip grip soles for hard floors.

Shop Slipper Socks →
Find Your Level

Which warmth level fits your life?

Now that you know what the numbers mean, find your match. One question.

Where will you wear them most?
How active will you be?
Your warmth level

Shop this tier
Choosing Your Level

Match the sock to the situation

Each warmth level fits a different part of your day. Scroll to find yours.

🏠

At home

2.3 TOGORIGINAL™ · 7×

Low activity, cold floors, sitting or standing still. Your feet aren't generating heat through movement. Maximum insulation for exactly this kind of cold. For tile, hardwood, or stone floors, slipper socks add a grip sole to the same 2.3 TOG warmth.

I wear them all the time at home as floors cold cause I'm cheap and don't like to turn heat up. My feet stay warm.Wendy M., ORIGINAL™ Twist Crew Socks
Shop ORIGINAL
👢

In boots or casual shoes

1.6 TOGLITE™ · 5×

The everyday tier. Fits inside boots and casual shoes without sizing up. Five times warmer than cotton. If your current winter strategy is a cotton sock inside a boot and your feet are still cold by lunchtime, LITE is the direct upgrade.

I love the extra warmth these heavier socks give me when the temperatures really plummet. Also appreciate that they're not too thick to fit comfortably inside my boots.Brenda W., Dahlia LITE™ Crew Socks
Shop LITE
👞

Dress shoes or work shoes

1.0 TOGULTRA LITE™ · 3×

Warmth in shoes that can't accommodate a thicker sock. Dress shoes, office shoes, fitted work shoes. Three times warmer than cotton. The thinnest construction Heat Holders makes.

So warm and soft. My feet are always cold and these fit in my shoes perfect.Rick T., Maddox ULTRA LITE™ Ankle Socks
Shop ULTRA LITE
🧍

Outdoors, standing still

2.3 TOGORIGINAL™ · 7×

Frozen sidelines. Fishing in the cold. Waiting outside. Walking the dog at dawn. Low body heat output. When your body isn't producing warmth through activity, you need the sock that holds onto whatever heat you've got.

Shop ORIGINAL
🚶

Outdoors, active

1.6 TOGLITE™ · 5×

Walking, hiking, working outside. Your body is generating heat. Too much insulation traps excess heat and moisture. LITE gives thermal protection without overheating. For physical outdoor work, WORXX™ uses ORIGINAL-level construction (2.3 TOG) with reinforced durability.

Shop LITE
❤️

Circulation conditions

2.3 TOGORIGINAL™ · 7×

Raynaud's, neuropathy, diabetes, peripheral artery disease. Cold feet from these conditions are persistent and resistant to the usual solutions. ORIGINAL provides the warmth that standard socks cannot. Non-binding top: warmth without constriction. Read our Raynaud's guide.

I have peripheral neuropathy and feet are always cold. These are the best I have found.Kim H., Dunnock ORIGINAL™ Twist Socks
Shop ORIGINAL
📦

One of each

All 3 tiersSock Drawer® 3-Pack

One pair from each warmth level: ORIGINAL, LITE, and ULTRA LITE. Match your socks to your day instead of choosing a single tier for every situation.

I got the 3 sock combination that gives 3 different warmth amounts - 3X, 5X and 7X. It's good to have a choice based on the weather.Ronnie S., Sock Drawer® Black 3-Pack
Shop Sock Drawer
What Customers Say

19,000+ reviews. The warmth system works.

Heat Holders has more than 19,000 verified customer reviews with a 4.9 average rating. Across those reviews, a pattern repeats: customers tried other socks first. Cotton, wool, "thermal" socks from other brands. Heat Holders was the one that worked. The TOG system is why. Measured warmth, not a marketing claim.

19,000+
verified customer reviews
4.9
average star rating
92%
five-star reviews
"I've bought so many different socks trying to keep my toes warm. I work outdoors and in the winter time I get chilblains on my toes. The Heat Holders Joshua Originals are the only socks that are very warm and keep my toes from getting chilblains."Les M., Men's Joshua ORIGINAL™ Crew Socks
"These are the only socks that warm up my cold feet, and keep them warm, without getting sweaty. I wear them to sleep nightly and it's a relief. Raynaud's runs in our family and these socks really help."Kelly F., Women's Snowdrop ORIGINAL™ Block Twist Socks
"My husband works door to door year round and can never keep his feet warm in winter. These are a complete game changer! Since he can wear them with any shoes he says his feet are the only warm part of his body on the frigid days."Garrett G., Men's Starling Stripe LITE™ Crew Socks
"The only socks that keep my feet warm." - Angela M.
"Same great sock in 3 different thickness/warmth level." - Carol O.
"A complete game changer." - Catherine W.
"I have original and LITE and could not be happier." - Chris R.
"Warm but not too thick." - Donna S.
"Worth every penny." - Gerald C.
"I have several pairs, all three levels." - Janet D.
"Perfect for lounging around the house." - Nancy H.
Common Questions

Frequently asked questions

TOG stands for Thermal Overall Grade. It measures thermal resistance: how effectively a fabric prevents heat from escaping through it. In technical terms, 1 TOG equals 0.1 m²·K/W (square meters kelvin per watt), which expresses the temperature difference across a material per unit of heat flow. In practical terms: a higher TOG number means the fabric holds more of your body heat in, and your feet stay warmer. The unit was developed in the 1940s by researchers F. T. Peirce and W. H. Rees at the Shirley Institute in Manchester, England. Their testing apparatus, the Shirley Togmeter, became the basis for BS 4745, the British Standard for thermal resistance of textiles. BS 4745 is still the international testing standard today. Its US equivalent is ASTM D1518. When you see a TOG number on Heat Holders packaging, the product was tested to this standard in a controlled lab environment.
Not always. The right TOG depends on the situation, not just the number. Higher TOG means more heat retention. ORIGINAL at 2.3 TOG is ideal when you're sitting still, standing in the cold, or at home on cold floors. Your body isn't generating much heat through activity, so you need maximum insulation to hold onto what you have. But if you're walking, hiking, or working a physical job, your body is producing heat through movement. A high-TOG sock can trap too much of that heat and moisture. Your feet overheat, sweat builds up, and the sock's thermal performance drops. LITE at 1.6 TOG gives thermal protection without creating that problem. ULTRA LITE at 1.0 TOG is the right choice when you need warmth in fitted shoes where a thicker sock simply won't fit. The three-tier system exists because one TOG level can't serve every situation. The goal is matching the insulation to the activity, not maximizing the number.
A standard cotton sock is approximately 0.3 TOG. This is the baseline against which Heat Holders measures all of its warmth multipliers: ORIGINAL at 2.3 TOG is 7× warmer, LITE at 1.6 TOG is 5× warmer, ULTRA LITE at 1.0 TOG is 3× warmer. Cotton's low TOG rating is only part of the problem. Cotton is also a moisture-absorbing fiber. Your feet produce sweat even at rest, even in winter. Cotton holds that moisture against your skin, and wet fabric conducts heat away from your body faster than dry fabric. So a cotton sock's effective thermal performance gets worse as you wear it. Heat Holders' thermal yarn does not absorb moisture the same way. The brushed inner pile traps warm air, not moisture, against your skin. The TOG number measures that difference.
TOG testing follows BS 4745, the British Standard for thermal resistance of textiles. The process uses a guarded hot plate apparatus (originally developed as the Shirley Togmeter). A fabric sample is placed on a heated plate that simulates skin temperature. A second plate above it represents the ambient environment. The instrument measures how much energy is required to maintain a constant temperature difference across the fabric at steady state. The less energy required, the better the fabric insulates, and the higher its TOG rating. The test is conducted under controlled conditions: fixed temperature, fixed airflow, fixed pressure on the sample. This removes variables and makes results comparable across products and manufacturers. Heat Holders tests every sock tier against this standard and publishes the result on packaging. The number you see (2.3 for ORIGINAL, 1.6 for LITE, 1.0 for ULTRA LITE) is the measured output of this test, not an estimate or a marketing figure.
TOG measures the same property in both cases: thermal resistance per unit area. A TOG is a TOG whether it's on a sock or a duvet. But socks and duvets solve very different thermal problems with very different constructions, which is why the numbers aren't directly comparable. A winter duvet might be rated 10.5 to 13.5 TOG. It achieves that through lofted fill (down, synthetic fiber, or hollow fiber) trapped between two large fabric panels. The loft creates deep pockets of still air across a large surface area. A sock rated 2.3 TOG achieves its insulation using dense, brushed yarn construction wrapped tightly around a small, curved surface. The construction method, the scale, and the thermal challenge are all different. The question to ask is not "how does a 2.3 TOG sock compare to a 4.5 TOG duvet?" but "how does a 2.3 TOG sock compare to a 0.3 TOG cotton sock?" That comparison, within the same product category and construction type, is where the TOG number becomes a useful decision tool. And the answer to that one is 7× warmer.
Heat Holders publishes TOG ratings for socks only. Base layers, gloves, hats, and other products use the same three-tier warmth system (ORIGINAL, LITE, ULTRA LITE) but do not carry a published TOG number. The reason is that TOG testing under BS 4745 uses a flat-plate method designed for flat textile samples. Socks can be tested this way because the fabric can be laid flat. Gloves, hats, and fitted base layers have three-dimensional constructions that don't map cleanly to the flat-plate test method. The tier names (ORIGINAL for maximum warmth, LITE for medium, ULTRA LITE for lightweight) indicate relative warmth within each product category and use the same thermal yarns and construction principles, but the specific TOG number applies to socks where the measurement is standardized and repeatable.
ORIGINAL socks are the thickest in the range. They fit comfortably in boots, roomy sneakers, and generous-fit footwear. They are too thick for fitted shoes. If you force an ORIGINAL sock into a tight shoe, the compression reduces the air pockets that provide the insulation, and your feet will be uncomfortable. For fitted footwear, LITE or ULTRA LITE are the right tiers. LITE (1.6 TOG, 5× warmer) fits standard boots and casual shoes without sizing up. ULTRA LITE (1.0 TOG, 3× warmer) fits dress shoes and work shoes where even a small increase in sock thickness changes the fit. Many customers own more than one tier and rotate by situation: ORIGINAL at home and in boots, LITE in casual shoes, ULTRA LITE in dress shoes. The Sock Drawer® 3-Pack is built for exactly this approach.
A reliable TOG rating comes from standardized lab testing under BS 4745 (or its US equivalent, ASTM D1518). These standards define the equipment, procedure, sample preparation, and environmental conditions for the test. The result is repeatable and comparable across products. Not all thermal sock brands test to a recognized standard. Some publish warmth claims based on internal testing or subjective assessments. Others use TOG numbers without referencing a testing standard at all. If a brand claims a specific TOG rating, look for three things: whether they name the testing standard (BS 4745 or ASTM D1518), whether they publish results consistently across their full range (not just one product), and whether the numbers are specific rather than rounded estimates. Heat Holders tests every sock tier to BS 4745, publishes the result on every package (2.3, 1.6, and 1.0 for the three tiers), and prints the warmth multiplier alongside it. The specificity of the number is part of the point. A figure like 2.3 comes from a lab. A figure like "up to 5×" comes from a marketing department.

Heat Holders is a thermal comfort brand, not a medical provider. The warmth information on this page is based on standardized TOG testing under BS 4745. If you experience persistent cold feet or symptoms related to circulation, consult a healthcare professional. TOG ratings are measured under controlled laboratory conditions; real-world thermal performance varies depending on activity level, footwear, and environmental conditions.

Last updated August 2026. Thermal specifications checked against current Heat Holders product data and BS 4745 testing standard.