21 Stone to KG
Convert 21 stone to kilograms and pounds instantly.
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Medically ReviewedRounded to 2 decimal places. Standard UK/IE ratio (1 st = 6.35029 kg).
21 stone is 133.36 kilograms. Multiply 21 by 6.35029 to get 133.356 kg, rounded to 133.36 kg. In pounds, 21 stone is exactly 294 lb, which leaves just 6 lb of daylight before the 300-pound mark. For more whole-stone conversions, visit our stone to kg converter or our comprehensive stone to kg chart.
This is one of those conversions I see people do when a scale or app quotes pounds and their brain still thinks in stone. 21 stone sits at 294 lb, six pounds short of 300, so it shows up a lot in weight-loss journals and gym spreadsheets where someone is tracking the run-up to a triple-digit pound total. The maths itself is clean because whole stones convert exactly: no awkward decimals, just 133.36 kg and 294 lb every time.
21 stone = 294 lb, six pounds short of the 300 lb mark
Because 300 lb is 21 stone 6 pounds, anyone sitting at 21 stone has exactly 6 lb before they hit that triple-digit pound milestone. That closeness is why 21 stone feels psychologically heavier than the number itself: it is the last whole-stone stop before 300 pounds, so people watch it closely when they are tracking in both units.
How does 21 stone compare by height?
These BMI values are calculated as kilograms divided by height in metres squared. BMI is a rough screening measure, not a diagnosis, so treat the categories as a starting point rather than a verdict. At 21 stone the BMI sits in the obese range (30+) at every adult height, from 57.7 at 5ft 0in down to 37.7 at 6ft 2in.
| Height | KG | BMI | Category |
|---|---|---|---|
| 5ft 0in (152cm) | 133.36 kg | 57.7 | Obese |
| 5ft 2in (157cm) | 133.36 kg | 54.1 | Obese |
| 5ft 4in (163cm) | 133.36 kg | 50.2 | Obese |
| 5ft 6in (168cm) ★ UK avg | 133.36 kg | 47.3 | Obese |
| 5ft 8in (173cm) | 133.36 kg | 44.6 | Obese |
| 5ft 10in (178cm) | 133.36 kg | 42.1 | Obese |
| 6ft 0in (183cm) | 133.36 kg | 39.8 | Obese |
| 6ft 2in (188cm) | 133.36 kg | 37.7 | Obese |
Weights Close to 21 Stone
Whole stones convert to exact pound figures because one stone is defined as 14 lb, so every row below is precise with no rounding.
| Stone | Kilograms | Pounds | Decimal Stone |
|---|---|---|---|
| 16 stone | 101.60 kg | 224 lbs | 16.00 st |
| 17 stone | 107.96 kg | 238 lbs | 17.00 st |
| 18 stone | 114.31 kg | 252 lbs | 18.00 st |
| 19 stone | 120.66 kg | 266 lbs | 19.00 st |
| 20 stone | 127.01 kg | 280 lbs | 20.00 st |
| 21 stone (this page) | 133.36 kg | 294 lbs | 21.00 st |
| 22 stone | 139.71 kg | 308 lbs | 22.00 st |
| 25 stone | 158.76 kg | 350 lbs | 25.00 st |
Frequently Asked Questions
How many kilograms are in 21 stone?
21 stone is 133.36 kg. Multiply 21 by 6.35029 to get 133.356 kg, which rounds to 133.36 kg. That is the exact figure every scale, chart and app should agree on.
What is 21 stone in pounds?
21 stone is exactly 294 lb. Since each stone is 14 lb, the arithmetic is 21 x 14 = 294, with no rounding involved.
How do I convert 21 stone to kg by hand?
Multiply 21 by 6.35029, which gives 133.356 kg, rounded to 133.36 kg. If you want a quick mental estimate, multiply 21 by 6.35 for 133.35 kg, then add a fraction for the leftover 0.00029.
Is 21 stone the same as 300 pounds?
No, 21 stone is 294 lb, which is 6 lb short of 300 pounds. 300 lb is 21 stone 6 pounds, so 21 stone is the last whole-stone milestone before the 300-pound mark.
What does 21 stone mean for BMI?
At 21 stone (133.36 kg), BMI falls in the obese range (30+) at every adult height, from 57.7 at 5ft 0in down to 37.7 at 6ft 2in. BMI is a screening measure that needs height context, and it cannot describe any individual's health on its own.
Dr Muhammad Usman
Dr Muhammad Usman graduated with his MBBS from Avicenna International Medical University in Bishkek, Kyrgyzstan (2019–2024).
He brings clinical training across general medicine, surgery, and public health, and writes the site's health information for UK readers in clear, practical language.