How to Measure Your Waist for Health (Where the Tape Goes)

Where exactly does the tape go?

Measure at the widest part of your belly, standing relaxed.

• The widest part of your belly. Stand relaxed and wrap the tape around the widest part of your belly. Use the same spot each time. The Midline app uses this spot too, because it's easy to find.

David Unwin, on The Diary Of A CEO, runs his at-home check around the fattest part of your belly (David Unwin, The Diary Of A CEO). What matters is using the same spot every time, so this week's number compares with last month's.

How do you get a reading you can trust?

Small things move the number. This checklist keeps it fair:

1. Stand with your feet close together, arms by your sides, weight even.
2. Measure against skin or thin clothing.
3. Keep the tape level with the floor all the way round. Snug, not digging in.
4. Relax, take a couple of normal breaths, and read the tape at the end of a normal breath out.
5. Don't suck in. Pulling your belly in makes the reading smaller.
6. Measure twice. If the two readings are within 1 cm (under half an inch), use the average. If not, measure again.

Food, drink and gas in your gut change the reading too. Same time of day, ideally before breakfast, keeps it fair.

What do the numbers mean?

Check	Line	Source
Waist, rough sign	40 in (102 cm) or more in men, 35 in (89 cm) or more in women	Rhonda Patrick, The Diary Of A CEO
Waist-to-height ratio	Under 0.5 (waist under half your height)	David Unwin, The Diary Of A CEO

Rhonda Patrick treats a waist at or over her lines as a rough sign of too much visceral fat, not a diagnosis. Two people with the same waist can carry very different amounts of visceral fat.

Waist-to-height ratio adjusts for how tall you are. David Unwin, on The Diary Of A CEO, uses it as a simple at-home check: your waist should be less than half your height. Our calculator does the maths.

If your result worries you, talk to your doctor.

Can a tape measure your visceral fat?

No. Visceral fat is the fat packed deep inside your belly, around your organs. A tape can't see it: only a scan, like an MRI or DEXA, measures it. Your waist is a rough guide, not a diagnosis.

Three experts in our library make the same point in practical terms. Sean O'Mara, on YouTube, shows two MRI scans with the same waist size and very different visceral fat, so tracking waist alone misses that (Sean O'Mara, YouTube). Peter Attia, on The Diary Of A CEO, says his clinic measures visceral fat with a DEXA scan (Peter Attia, The Diary Of A CEO).

On a March 2026 Diary of a CEO episode, Rhonda Patrick used waist size as a rough sign of too much visceral fat: 35 inches or more for women, 40 or more for men. She said a DEXA scan is how you'd measure it directly.

On a May 2026 episode about fatty liver, David Unwin showed a version with no tape at all. Cut a piece of string as long as you are tall and fold it in half. Wrap it around the widest part of your belly. If the ends overlap, your waist is under half your height. It's the same half-your-height rule, minus the maths.

How often should you measure?

Once a week is plenty. That's our routine, not a medical rule. Waists change slowly, and daily readings bounce around with meals and drinks. Same day, same time, same spot.

Check first: if measuring your body makes you anxious, or you've had an eating disorder, skip the tape and talk to your doctor instead. Don't use it during pregnancy.