Treadmills: how much motor power you actually need

One treadmill claims six horsepower, the next claims two and a half — and the two-and-a-half is the pricier machine. That isn't a printing error. It's two different ways of measuring, and it's where most buyers take their first wrong turn.

The motor is the most expensive part of a treadmill and the one part you can't upgrade later. But before you get to it, answer the question that settles everything else: will you mostly walk on this, or run? A walking machine and a running machine are two different products, even when they stand side by side in the shop.

What a treadmill genuinely needs

This is the list I wouldn't compromise on at any price:

• A safety key on a cord that cuts the belt the moment you drift away from the console.
• A frame that doesn't sway when you stand on the edge of the belt and shift your weight sideways.
• A belt long enough for your stride, not for the average user in the brochure.
• A motor that holds your pace without overheating, rather than one that manages it on paper.
• Incline, motorised if possible — it's the most useful feature on a home treadmill.
• A display that shows speed, time, distance and incline at a glance, without menu-hunting.

Everything else — training programmes, apps, fans, big screens — is comfort. Grip pulse from the metal handles is a rough estimate at best, so don't build heart-rate zones on it; a chest strap or a sports watch does that job properly.

The specs, and what each one actually means

Motor power

There are two figures. Continuous power (often labelled CHP) tells you what the motor can sustain for hours. Peak power is a brief maximum, and it gets the bigger typeface because it's the bigger number. If a spec sheet lists one figure with no explanation, assume it's the peak.

Rough guidance for continuous power, for a user up to about 90 kg:

• 1.5–2.0 hp — walking and brisk walking up to 6–7 km/h, including on incline.
• 2.0–2.5 hp — a mix of walking and easy running up to 10 km/h, three or four times a week.
• 2.5–3.5 hp — regular running, intervals, sessions over 45 minutes, or several people in the household.

Add roughly 0.5 hp if you're over 100 kg or planning daily long sessions. An underpowered motor doesn't fail dramatically; it simply runs at its limit, gets hot, ages its own electronics, and a year or two in the belt starts stuttering when you change pace or raise the incline.

Maximum user weight

Home machines are typically rated somewhere between 100 and 180 kg. That figure is a test limit, not a target, so leave at least 20 per cent of headroom: at 95 kg, a 100 kg rating is too tight and a 130 kg rating is about right.

The reason is impact — running lands with a force several times your body weight, and the margin goes into the bearings, the deck and the motor mount. If your weight moves around during the year, plan for the top of that range rather than whatever the smart scale showed this morning.

Belt length and width

This is the spec people underestimate most, and it decides whether running feels natural or cramped. The faster you run, the longer your stride and the more belt you need in front of and behind you.

• Walking: 120–130 cm long, 40–45 cm wide is enough.
• Running up to 12 km/h: at least 140 cm long and 45–50 cm wide.
• Faster running, or if you're over 185 cm tall: 150 cm or more, with 50–55 cm of width.

A narrow belt is worse than it sounds. You shorten your stride without noticing and tuck your arms in to avoid clipping the frame, and twenty minutes later you feel it in your shoulders and back rather than your legs.

Cushioning and the deck

Under the belt sits a board, usually 18–25 mm thick, resting on elastomers. A thicker deck and better elastomers mean less shock through the joints and less noise. A treadmill is softer than tarmac, but it doesn't cancel impact — if your knees complain, the cause is more often a sudden jump in weekly mileage than the surface, which we covered in the piece on preventing knee injuries.

Speed and incline

Home treadmills usually top out at 16–20 km/h. It looks good on the box, and most people never exceed 12–14 km/h. Incline is the more useful number: 0–10 per cent covers nearly everything, and 12–15 per cent is a bonus. Walking at 5 km/h on an 8–12 per cent gradient lifts your heart rate like easy running, with far less impact.

Rollers, belt and frame

Rollers of 4–5 cm in diameter are the budget solution; 6–8 cm means the belt bends less sharply, which means less friction and less strain on the motor. A multi-ply belt outlasts a single-ply one. A steel frame is heavier and calmer than aluminium, and a machine weight of 60–100 kg on a running model is a feature rather than a flaw — heavier machines shift and resonate less.

Space and money, realistically

The machine itself takes up roughly 160–200 cm of length and 70–95 cm of width. It isn't the whole requirement:

• At least 100 cm clear behind the belt, and 200 cm is safer — that's where you end up if you stumble.
• 30–60 cm at each side, for stepping off and for cleaning underneath.
• Ceiling height: your height plus 20–30 cm, measured from the belt, which sits 15–25 cm above the floor. Basements and loft rooms fail this more often than people expect.

Folding frames save length, not width, and they don't fix a room that's too small. If you have to unfold and drag the thing every time, you'll use it less — which is the most expensive consequence of a bad choice.

A 6–10 mm rubber mat under the machine protects the floor, cuts vibration passing to the neighbours below, and stops the treadmill creeping. That's a different object from the exercise mat you stretch on — a thick foam mat under a treadmill is actively unhelpful, because the machine sinks into it and starts to rock.

On price, think in tiers rather than figures. Handle-free walking pads sit at the bottom; entry-level folding machines come next; the middle brings 2.5 hp or more, a 140 cm belt and decent cushioning; semi-commercial machines can cost five to ten times the cheapest option. The money goes into the motor, belt length, frame and warranty — not the screen.

Budget for running costs too: 0.3–1.0 kWh per training hour, silicone lubricant every three to six months or roughly every 50 hours of use, plus occasional belt centring and tensioning. A motor warranty of anywhere from 2 to 10 years is usually the most honest line in the whole catalogue.

Common buying mistakes

• Comparing peak figures. Two machines badged "6 hp" can hide completely different motors.
• Buying a belt that's too short. Ten centimetres saved is ten centimetres you notice every session.
• No weight headroom. Matching the rating exactly to your body weight shortens the machine's life.
• Forgetting the run-off zone and ceiling. Measure the room before you measure the treadmill.
• Chasing top speed while ignoring incline, which you'll actually use daily.
• Buying for motivation. A machine doesn't build a habit; it removes an excuse for someone already training.
• Ignoring noise. In a flat, footfall through the floor is a louder problem than the motor.
• A thin extension lead. A treadmill wants its own socket, ideally not sharing a circuit with heavy appliances.

Who it pays off for, and who should skip it

It's worth it if you already train three or more times a week and darkness, rain, shift work or childcare regularly cost you a session. It's also worth it if incline walking is your main conditioning habit — that's probably the best ratio of training effect to joint load any home machine offers.

Past fifty, a treadmill is often the most reliable way to keep conditioning going all year, because you control surface and pace precisely; how to fit that around the rest of the week is covered in our piece on training sensibly at 50.

Skip it if you run once a week and enjoy being outside, if you can't clear a proper safety zone behind the machine, or if your budget only stretches to something weaker than your training needs. In that case a gym membership, or kit that doesn't claim half a room, serves you better.

When to see a doctor

Stop and get checked if effort brings chest pain or pressure, dizziness, fainting, an irregular heartbeat, or breathlessness out of proportion to your pace. The same applies if you have known heart disease, uncontrolled blood pressure, or you're returning to training after a long illness.

For joints the rule is simpler: pain that lasts more than two weeks, worsens session by session, or wakes you at night isn't something you fix by adjusting the treadmill.

The short version

• Judge motors by continuous power: 1.5–2.0 hp for walking, 2.0–2.5 for easy running, 2.5–3.5 for regular running.
• Add about 0.5 hp above 100 kg, and leave 20 per cent headroom on the weight rating.
• 140 cm of belt is the threshold for running; under 130 cm it's a walking machine.
• The room needs 100–200 cm clear behind the belt and a ceiling at least 20 cm above your head while you're on it.
• You'll use incline every session and top speed almost never.