Men's sizes

Women's sizes

Pick your size by your hips.

The heat works best when the panels sit against you. So they're cut close, with an elastic waist and enough stretch to stay comfortable all day. The hip is the main fit point. These are body measurements. Measure yourself, not a pair of pants. Allow ±0.5–0.75" (1–2 cm).

1. Measure your hips. Stand with your feet together. Wrap a soft tape around the fullest part of your hips and seat.
2. Measure your waist. Stand relaxed. Measure around your natural waist, just above your hips. Don't pull the tape tight.
3. Pick your size. Match your hip measurement to the chart first. Wearing them under jeans or work trousers? Stay true to size. Wearing thicker outer layers or want more room? Size up. We've updated our size labels based on customer feedback. If you've ordered before, check the chart again. Your size may have changed.

Between sizes, or larger hips or thighs? Size up. The elastic waist will adjust, but the hip won't. Still not sure? Email us your measurements and we'll tell you which size to get. And if they don't fit, our 60-Day Fit Guarantee covers free size exchanges.

Warm legs, without the bulk.

Dawn dog walks. Cold commutes. Long shifts outside. Thermal leggings help a little, but they bunch under your jeans and still leave you cold. HearthLayer pants put the heat right against your waist, hips, thighs and calves, under whatever you already wear.

• Warm in 30 seconds. 12 ThermoSphere™ heat panels cover your waist, hips, thighs and calves. Hold the button, and you feel the heat within 30 seconds.
• Heat you control. Three levels: Low, Medium and High. One press switches between them. Go from a gentle boost indoors to serious warmth outside.
• All day on one charge. Up to 12 hours on Low with the included 10,000 mAh power bank.
• No bulk. The panels are ultra-thin, flexible carbon, built into stretch fabric. They slip under jeans, work trousers, riding pants or salopettes without bunching.

Where they work best: commuting, outdoor work, dog walks, spectating, camping, motorcycling, skiing, and staying warm at home. During hard runs or intense training, your legs make plenty of their own heat. Most people use Low or switch off while active, then turn it up on breaks.

Try them for 60 days. If they're not for you, our 60-Day Money-Back Guarantee has you covered.

Built to stay safe. They run on 5V USB — the same voltage as charging your phone. Built-in sensors keep the heat steady and adjust it automatically if it gets too hot. FCC certified.

What are they made of?

• Polyester / elastane stretch blend — a close-to-body fit that moves with you
• 12 ThermoSphere™ carbon panels — ultra-thin and flexible, across your waist, hips, thighs and calves
• Sealed, insulated heating elements — protected against moisture, so they survive the washing machine
• Internal power bank pocket — low-profile, near the hip, with a short routed cable

How do I wash them?

• Take the power bank out first. Unplug it and remove it from the pocket every time.
• Machine wash cold. Close all fastenings, put them in a laundry bag, and use a gentle cycle.
• Line dry only. No tumble dryer.
• Skip the harsh stuff. No bleach, no ironing, no dry cleaning. They can damage the heating panels.

What's in the box

• 1 pair of HearthLayer™ Heated Baselayer pants with 12 ThermoSphere™ panels
• 1 10,000 mAh power bank (up to 12 hours of heat)
• 1 USB cable for charging your power bank

Wear them every day. They're machine washable, so you can treat them like any other base layer. Just remember: power bank out before they go in the wash.

The power bank is included.

Every order comes with our 10,000 mAh power bank. That gives you up to 12 hours of heat on Low. Medium and High use more power, so the heat lasts a shorter time.

How to turn them on

1. Plug in the power bank. Connect it to the cable inside the internal pocket near your hip. It sits flat under your outer layers.
2. Hold the button for 3 seconds. The light comes on and you feel the warmth within 30 seconds.
3. Press to change the level. Each press cycles through Low, Medium and High. The light colour shows your setting.

Power

• 5V USB. Low voltage, no mains electricity, no exposed wiring.
• Works with any standard 5V USB power bank. Handy if you want a spare for longer days.
• Automatic temperature control. Sensors watch the heat and adjust it so it never goes past your chosen level.

Charge it overnight. Plug the power bank in when you take the pants off. It's ready for the whole day by morning.