What is the waist to height ratio?
The waist to height ratio (WHtR) is one of the simplest and most reliable ways to check whether you are carrying too much fat around your middle. You work it out by dividing your waist measurement by your height, using the same units for both. For example, someone with a 71 cm waist and a height of 170 cm has a ratio of 71 / 170 = 0.42.
The fat stored around your abdomen, called central or visceral fat, sits close to vital organs and is more strongly linked to heart disease, stroke and type 2 diabetes than fat stored elsewhere. Because the ratio focuses on this area, it can flag a health risk that body weight alone might miss. The headline rule is easy to remember: keep your waist to less than half your height.
Why use it instead of just BMI?
BMI is useful, but it only compares your overall weight to your height and tells you nothing about where your fat is stored. The waist to height ratio fills that gap. Used together, the two give a much clearer view of your health than either one alone.
| Measure | What it shows | Strength | Limitation |
|---|---|---|---|
| Waist to height ratio | Belly fat relative to height | Simple "under half your height" rule; flags central fat early; works across ages and heights | Needs an accurate waist measurement |
| BMI | Weight relative to height | Quick and widely used | Ignores fat location; can misjudge very muscular people |
| Waist to hip ratio | Fat distribution (waist vs hips) | Captures overall body shape | Needs two measurements; less standardised |
Waist to height ratio chart
These categories are based on the widely used Ashwell boundaries. The same values apply to adult men and women, which is part of what makes the ratio so practical.
| Ratio | Category | What it generally means |
|---|---|---|
| Below 0.4 | Take care | May suggest you are underweight. Focus on nourishing meals; there is no need to reduce your waist. |
| 0.4 to 0.49 | Healthy | Low risk. Keep up your current habits. |
| 0.5 to 0.59 | Increased risk | Your waist is more than half your height. Consider trimming it with diet and activity. |
| 0.6 or above | High risk | Higher risk of heart disease and type 2 diabetes. Taking action now is worthwhile. |
How to measure your waist correctly
- Stand up straight and breathe out normally. Do not hold your breath or pull your stomach in.
- Find the midpoint between the bottom of your ribs and the top of your hip bones. This is usually just above your belly button.
- Wrap a tape measure snugly around this point, keeping it level all the way around, without pressing into the skin.
- Note the measurement and make sure your waist and height use the same units.
How to reduce your waist naturally
You cannot spot-reduce fat from one area, but lowering your overall body fat will shrink your waist. Small, steady changes work far better than crash diets.
🥗 Eat more whole foods and fiber
Build meals around vegetables, fruit, beans, whole grains and lean protein. Fiber keeps you full and helps reduce belly fat over time.
🥤 Cut back on sugar and processed foods
Sugary drinks, refined carbs and ultra-processed snacks are closely linked to fat around the middle. Swapping them out is one of the most effective changes you can make.
🆙 Move most days
Aim for at least 150 minutes of moderate activity a week, and add strength training twice a week. Muscle helps your body burn more energy at rest.
🧘 Manage stress and sleep well
Ongoing stress and poor sleep raise cortisol, which encourages your body to store fat around the abdomen. Prioritise 7 to 9 hours of sleep and build in time to unwind.
📏 Track and stay consistent
Re-measure your waist every few weeks rather than daily. Consistency over months is what moves your ratio in the right direction.
Who should not use this calculator
The waist to height ratio is not suitable for everyone. Do not use it if any of the following apply:
- The person is under 5 years old.
- You are pregnant.
- You have been diagnosed with an eating disorder, or think you may have one.
- You have a growth disorder or another condition that affects your height.
- Your BMI is over 35 (adults aged 18 and over).
For children and teenagers aged 5 to 17, check their BMI first and use this tool with a parent or carer. If you are unsure or concerned about your waist size, speak to a pharmacist or GP.