Converting 138 kilograms gives 21 st 10.2 lb. One multiplication does it — 138 × 0.1574730444 = 21.7312801297 stones — and because the factor is defined rather than measured, that answer will not drift over time.
At 138 kg, BMI works out to 53.9 at 1.60 m, 47.8 at 1.70 m, 42.6 at 1.80 m and 38.2 at 1.90 m. The healthy band tops out at 25, so the same weight can sit in three different categories depending on height — which is the whole limitation of the index.
Plenty of people do this in their head: divide by 6.4 instead of using the exact factor 0.1574730444. At 138 that shortcut gives 21.5625 stones, off by 0.1688 stones or about 0.78%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
The formula
138 kg- The quantity being converted
0.1574730444- Exact stones in one kilogram
21.73128013 st- The converted result
How it works, step by step
- Begin from the figure you have: 138 kilograms.
- Multiply by 0.1574730444, the exact number of stones in one kilogram.
- That gives 21.7312801297 stones, or 21 st 10.2 lb.
- The reverse works the same way with division: 21.73128013 st ÷ 0.1574730444 = 138 kg.
Worked examples
Working it through
138 kg × 0.1574730444 = 21.7312801297 st (21 st 10.2 lb). One multiplication, with no rounding until the value reaches the screen.
Checking it backwards
Divide the answer back: 21.73128013 st ÷ 0.1574730444 returns 138 kg. If a converter fails this test it has inverted the factor, which is the single most common conversion error there is.
How to read your score
Frequently asked questions
What is 138 kilograms in stones and pounds?
138 kilograms is exactly 21 st 10.2 lb. Carried to full precision that is 21.7312801297 stones.
How do you convert kilograms to stones?
One step: multiply the kilogram figure by 0.1574730444. Here that is 138 × 0.1574730444 = 21.73128013 stones.
What is 21.73128013 stones back in kilograms?
138 kilograms. Dividing by 0.1574730444 undoes the conversion exactly.
How much is 138 kg in practice?
At 138 kg, BMI works out to 53.9 at 1.60 m, 47.8 at 1.70 m, 42.6 at 1.80 m and 38.2 at 1.90 m. The healthy band tops out at 25, so the same weight can sit in three different categories depending on height — which is the whole limitation of the index. The table lower down places it beside its neighbours so you can see where it sits.
What is a kilogram?
The SI base unit of mass, redefined in 2019 in terms of the Planck constant.
What is a stone?
Fourteen pounds — still the customary way to state body weight in the UK and Ireland.
138 kg in stones — nearby values
| Kilograms | Stones | Unrounded |
|---|---|---|
| 132 kg | 20 st 11 lb | 20.78644186 |
| 133 kg | 20 st 13.2 lb | 20.94391491 |
| 134 kg | 21 st 1.4 lb | 21.10138795 |
| 135 kg | 21 st 3.6 lb | 21.258861 |
| 136 kg | 21 st 5.8 lb | 21.41633404 |
| 137 kg | 21 st 8 lb | 21.57380709 |
| 138 kg | 21 st 10.2 lb | 21.73128013 |
| 139 kg | 21 st 12.4 lb | 21.88875317 |
| 140 kg | 22 st 0.6 lb | 22.04622622 |
| 141 kg | 22 st 2.9 lb | 22.20369926 |
| 142 kg | 22 st 5.1 lb | 22.36117231 |
| 143 kg | 22 st 7.3 lb | 22.51864535 |
| 144 kg | 22 st 9.5 lb | 22.6761184 |
Exact factor: 1 kilogram = 0.157473044418 stones. The row for 138 kg is the value this page is about.