42 kilograms works out to 6 st 8.6 lb. The calculation is 42 × 0.1574730444, and the unrounded result is 6.61386786555 stones, which is the number to use if this feeds into anything else.
At 42 kg, BMI works out to 16.4 at 1.60 m, 14.5 at 1.70 m, 13 at 1.80 m and 11.6 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 42 that shortcut gives 6.5625 stones, off by 0.05137 stones or about 0.78%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
The formula
42 kg- The quantity being converted
0.1574730444- Exact stones in one kilogram
6.613867866 st- The converted result
How it works, step by step
- Begin from the figure you have: 42 kilograms.
- Scale it by 0.1574730444 — that is how many stones fit in a single kilogram.
- That gives 6.61386786555 stones, or 6 st 8.6 lb.
- Going the other way, divide rather than multiply — 6.613867866 st ÷ 0.1574730444 brings you back to 42 kg.
Worked examples
Working it through
Because this is a straight proportion, 42 kg × 0.1574730444 = 6.61386786555 st (6 st 8.6 lb) — no offset, no second term, nothing else to account for.
Verifying the result
Run it in reverse — 6.613867866 st ÷ 0.1574730444 = 42 kg. Matching the input you started from is the proof the direction is right.
How to read your score
Frequently asked questions
What is 42 kilograms in stones and pounds?
42 kilograms is exactly 6 st 8.6 lb. Carried to full precision that is 6.61386786555 stones.
How do you convert kilograms to stones?
Multiply by 0.1574730444. So 42 × 0.1574730444 = 6.613867866 stones. The factor comes from a definition rather than a measurement, so it never changes.
What is 6.613867866 stones back in kilograms?
Divide by 0.1574730444, or multiply by 6.35029318 — either returns 42 kilograms.
Is 42 kg a lot?
At 42 kg, BMI works out to 16.4 at 1.60 m, 14.5 at 1.70 m, 13 at 1.80 m and 11.6 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.
42 kg in stones — nearby values
| Kilograms | Stones | Unrounded |
|---|---|---|
| 36 kg | 5 st 9.4 lb | 5.669029599 |
| 37 kg | 5 st 11.6 lb | 5.826502643 |
| 38 kg | 5 st 13.8 lb | 5.983975688 |
| 39 kg | 6 st 2 lb | 6.141448732 |
| 40 kg | 6 st 4.2 lb | 6.298921777 |
| 41 kg | 6 st 6.4 lb | 6.456394821 |
| 42 kg | 6 st 8.6 lb | 6.613867866 |
| 43 kg | 6 st 10.8 lb | 6.77134091 |
| 44 kg | 6 st 13 lb | 6.928813954 |
| 45 kg | 7 st 1.2 lb | 7.086286999 |
| 46 kg | 7 st 3.4 lb | 7.243760043 |
| 47 kg | 7 st 5.6 lb | 7.401233088 |
| 48 kg | 7 st 7.8 lb | 7.558706132 |
Exact factor: 1 kilogram = 0.157473044418 stones. The row for 42 kg is the value this page is about.