Waist-to-Height Ratio
Last updated: August 2026
Keep your waist to less than half your height. That is the entire rule, it needs nothing but a tape measure, and it captures what the scale cannot: where your body stores fat, not just how much you weigh.
Health services now recommend it alongside — sometimes ahead of — BMI, because fat around the middle behaves differently from fat elsewhere. Below: the 0.5 threshold, how to measure properly, and target sizes for every height.
The 0.5 rule
Divide your waist by your height, same units. A waist of 84 cm at 175 cm tall is 84 ÷ 175 = 0.48; a 33-inch waist at 69 inches is 0.48 too — it is a ratio; units cancel.
| Ratio | Category | What it suggests |
|---|---|---|
| Below 0.4 | Possibly too low | Worth checking with a doctor, especially if unintentional |
| 0.4 – 0.49 | Healthy | Central fat in the range associated with lowest risk |
| 0.5 – 0.59 | Increased risk | A useful prompt to act, not a diagnosis |
| 0.6 and above | High risk | Worth discussing with your doctor |
The rule needs remarkably few exceptions: one threshold for men and women, most ethnic groups, and children from about age five — where BMI needs sex ranges, ethnicity cutoffs, and separate charts. Crossing 0.5 is a screening prompt, not a verdict: worth raising alongside blood pressure, blood sugar, and cholesterol at your next check-up.
How to measure your waist correctly
Almost all the error is the wrong place or a tight tape. Ninety seconds of care gives a number you can compare month to month.
- Bare skin, or one thin layer.
- Find the level: midway between the bottom of your lowest rib and the top of your hip bone. Feel for both — often at or just above the navel, but the landmarks matter, not the belly button.
- Stand normally, no sucking in. Breathe out naturally, then measure.
- Keep the tape level all the way around — check a mirror; it rides up at the back.
- Snug, not tight. If it leaves a mark, ease off.
- Measure twice; if they differ by over a centimeter, take a third and use the middle.
Three habits skew it: trouser size (commonly one to two inches smaller than reality), measuring at the hips (flatters the ratio), and inconsistent timing — waist varies a couple of centimeters across a day. Morning, before eating, is most repeatable, the same logic behind consistent weigh-in timing.
Target waist size by height
If you would rather not divide anything, stay under half your height:
| Height | Height (ft/in) | Keep waist under | In inches |
|---|---|---|---|
| 150 cm | 4 ft 11 in | 75 cm | 29.5 in |
| 155 cm | 5 ft 1 in | 77.5 cm | 30.5 in |
| 160 cm | 5 ft 3 in | 80 cm | 31.5 in |
| 165 cm | 5 ft 5 in | 82.5 cm | 32.5 in |
| 170 cm | 5 ft 7 in | 85 cm | 33.5 in |
| 175 cm | 5 ft 9 in | 87.5 cm | 34.5 in |
| 180 cm | 5 ft 11 in | 90 cm | 35.5 in |
| 185 cm | 6 ft 1 in | 92.5 cm | 36.5 in |
| 190 cm | 6 ft 3 in | 95 cm | 37.5 in |
You may have seen fixed thresholds — 94 cm (37 in) for men, 80 cm (31.5 in) for women. Still useful, but they ignore height: unkind to short people, generous to tall ones. The ratio scales properly.
Why it complements BMI rather than replacing it
BMI asks how heavy you are for your height; the ratio asks where the mass sits. The interesting cases are the disagreements.
- Normal BMI, high ratio. The case BMI misses most — normal-weight central obesity: visceral fat around the organs despite a reassuring weight — the kind most tied to type 2 diabetes, high blood pressure, and heart disease.
- High BMI, healthy ratio. Common in muscular people — the extra weight is usually muscle.
- Both healthy. Two independent measures agreeing beats either alone.
- Both raised. A clear prompt to talk to your doctor about activity, sleep, alcohol, diet.
The ratio also moves in a way that feels fair: activity reduces visceral fat early, so a waist can shrink while the scale barely moves. If the scale has stalled but your waist is falling, you are progressing. For the fullest picture, add body fat percentage and check your weight against healthy weight for your height.
Keeping a record: tape and notebook vs app
Measure once and you have a snapshot; monthly for a year, something genuinely informative — and a notebook does that in twelve lines. The gap shows up when you want your waist next to your weight over the same months, where the useful story lives.
The free Weight & BMI Feeltracker app keeps that history: weight in kilograms or pounds, BMI calculated automatically, body fat percentage, and notes and photos on any entry — so a waist measurement lives beside its weigh-in. Charts, trend lines, goal tracking, and reminders are built in; it syncs with Apple Health and across your devices via iCloud — no account, no email — and exports to PDF, XLSX, CSV, or JSON for a doctor's visit. Optional AI insights summarize your history.
Either way, the tape does the real work. Keep it in the drawer with the scale and use it on the first of the month.
Frequently asked questions
What is a healthy waist-to-height ratio?
Below 0.5 — your waist should measure less than half your height. A ratio of 0.4 to 0.49 is the healthy band; 0.5 to 0.59 suggests increased risk, and 0.6 or above is worth discussing with your doctor.
Is waist-to-height ratio better than BMI?
It is better at one specific thing: spotting fat stored around the organs, which BMI cannot see at all. But BMI is quicker, universally understood, and better validated for population screening. Use both — they disagree in informative ways.
Where exactly should I measure my waist?
Midway between the bottom of your lowest rib and the top of your hip bone, on bare skin, standing normally, after breathing out. For many people that is at or just above the navel — but find the landmarks by feel rather than assuming.
Does the 0.5 rule apply to men and women equally?
Yes, which is one of its main advantages. The same threshold works for both sexes, across most ethnic groups, and for children from around age five — no separate charts or adjusted cutoffs needed.
How often should I measure my waist?
Monthly. Waist changes slowly, and measuring more often mostly captures day-to-day bloating rather than real change. Measure in the morning before eating, always with the same technique.
