Your Oura height is rounded — here's why it skews your BMI
Oura's API hands back your height in metres with a single decimal — 1.8, not 1.81 — so anything between 175 and 184 cm arrives as 180. It's a tiny rounding, but every body metric that divides by your height squared inherits it, which is why your BMI can read a notch off even when the scale is perfectly right.
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Where the rounding comes from
Height in the Oura app is stored to one decimal place in metres. When an app reads it back, 1.81 m and 1.84 m both come through as 1.8 — a resolution of 10 cm. Weight, by contrast, arrives to the kilogram, so the number that's usually least precise in a body calculation is the one that gets squared.
Why a centimetre matters for BMI
BMI is weight divided by height in metres squared, so height enters the formula twice over. At 80 kg, the difference between 1.80 m and 1.85 m is roughly a full BMI point — enough to shift you from one side of a band to the other on paper. The same height feeds your estimated body-fat read and your healthy-weight range, so one rounded figure quietly ripples through the whole Body page.
Type it once, fixed everywhere
Vitra now lets you set your exact height by hand: tap the height figure on your Profile and enter the real value in centimetres or inches. Your entry takes priority over Oura's rounded number and is used everywhere height appears — BMI, body-fat estimate, healthy-weight range and the Body Score. It's stored locally on your machine, like the rest of your health data, and you only need to do it once.
Small inputs deserve the same care as the big ones. Getting height right is the cheapest way to make every downstream body number trustworthy — and it's a one-time, thirty-second fix.
Frequently asked questions
Pedro Thomaz builds Vitra, a desktop app that reads Oura data against your own baseline instead of a population average. He has worn a ring daily for years and reads these same numbers every morning — which is where most of what is written here comes from. Vitra is not a medical device and nothing on this blog is medical advice.
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