Which Size Heat Pad for Which Body Part

If you’re buying one pad for the household, get a flat pad around 30 x 40 cm.

It covers a whole lower back, folds over a shoulder, sits on a belly and drapes over a knee. Almost every complaint in this house gets treated with that one size.

Buying for one specific problem, or buying a second pad? Then size to the body part.

Size by body part

Where it hurts	Size to look for	Notes
Lower back	30 x 40 cm or larger	Must span hip to hip. This is the size most people need and the one most often bought too small.
Upper back and shoulder blades	30 x 40 cm	Needs to cover both blades at once, or you treat one side and the other stays tight.
Neck and shoulders	Shaped wrap, or a flat pad folded	A wrap sits better on the slope of the shoulders. A flat pad works if you’re sitting upright.
Belly and period cramps	30 x 40 cm	Same pad as the back. Lie on your side with knees curled and rest it on top.
Knee	Small pad or a wrap with a strap	A big flat pad slides off a bent knee. A strap keeps it put while you move.
Elbow and wrist	Small pad or wrap	Small joints need contact, not coverage.
Hands	Small pad, or rest hands on top of a flat one	For morning stiffness, both hands on one pad works fine.
Hips and buttock	30 x 40 cm or larger	The painful spot often sits deeper and wider than you expect.

Row by row, the articles behind them: lower back, upper back, neck and shoulders, period cramps, knee, elbow, hands and hips.

The mistake almost everyone makes

Buying too small.

A pad that covers half the sore area means you spend the session shuffling it from one spot to the next, and each spot only gets a few minutes of warmth. Muscle needs around ten minutes under steady heat before it starts to let go. See how long to use a heating pad.

Worse, people compensate by turning the setting up. Hotter for less time is not the same as warm for twenty minutes, and it’s how skin gets damaged. See what temperature should a heating pad be? and toasted skin syndrome.

How to check before you order

Listings show dimensions in centimetres that mean nothing until you put them against your own body. Two minutes with a ruler settles it:

1. Find an A4 sheet of paper. That’s 21 x 30 cm.
2. Hold it against the sore area. For a lower back, one sheet usually looks obviously too small, which tells you what you need to know.
3. Two sheets side by side is roughly 42 x 30 cm, about the size of a standard flat pad.

Also measure the cord. From the socket to where you’ll actually sit or lie, add a little slack. A pad that reaches the sofa but not the bed gets used half as often.

Flat pad or wrap?

Flat pads are the all-rounder. They cover large areas, work in any position, and cost less. They don’t stay put on a joint you’re moving.

Wraps with straps hold contact on a knee, elbow, wrist or neck while you move around. The trade-off is that a strap adds pressure, and pressure traps heat against the skin. Keep wrap sessions on the lower settings and check your skin afterwards. The full comparison: heated wraps vs a flat pad.

If it’s a choice of one, take the flat pad. You can always sit against it or lay it over a joint. You can’t make a small wrap cover a back. For whole-body warmth rather than treating one area, see an electric blanket vs a heat pad.

Buying for someone else

• Elderly parents: bigger and lighter, with a controller that has clearly labelled settings rather than one button cycling through unmarked modes. See safe heat at home for elderly parents and giving a heat pad as a gift.
• Office use: a flat pad that fits between your lower back and the chair. See freezing in the office aircon.
• A whole clinic or gym: different question entirely. See heat pads for clinics, gyms and physiotherapy practices.

Size is only one of the things worth checking. The rest of the list: what a physio looks for in a heating pad, with what the price bands mean and where to buy one. And before buying at all, make sure heat suits your problem: heat or ice.

Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.