Kg to Stone and Pounds Converter | kg to st lb Calculator
Need the reverse conversion?
Convert st + lb to kg - if you have stones and pounds and need kilograms.Quick Reference: Common Body Weights
| Kilograms | Stones + Pounds | Context |
|---|---|---|
| 50 kg | 7 st 12 lb | Light adult |
| 60 kg | 9 st 6 lb | Average woman |
| 70 kg | 11 st 0 lb | Average adult |
| 80 kg | 12 st 8 lb | Average man |
| 90 kg | 14 st 2 lb | Large adult |
| 100 kg | 15 st 10 lb | Heavy adult |
Note: In the UK, stones are commonly used for body weight. Medical records typically use kilograms. Round to nearest 0.5 lb for fitness tracking.
Boxing & MMA Weight Classes
| Weight Class | Max Weight (kg) | Max Weight (st + lb) |
|---|---|---|
| Strawweight | 52.2 kg | 8 st 3 lb |
| Flyweight | 56.7 kg | 8 st 13 lb |
| Bantamweight | 61.2 kg | 9 st 9 lb |
| Featherweight | 65.8 kg | 10 st 5 lb |
| Lightweight | 70.3 kg | 11 st 1 lb |
| Welterweight | 77.1 kg | 12 st 2 lb |
| Middleweight | 83.9 kg | 13 st 3 lb |
| Light Heavyweight | 93.0 kg | 14 st 9 lb |
| Heavyweight | 120.2 kg | 18 st 13 lb |
Tip: Weight classes may vary slightly between organizations (UFC, WBC, IBF). Always check official rules for competition.
Frequently Asked Questions
What is a stone in weight measurement?
A stone is an imperial unit of weight equal to 14 pounds (approximately 6.35 kg). It is commonly used in the UK and Ireland for measuring body weight.
How do I convert kilograms to stones and pounds?
Divide your weight in kg by 6.35029318 to get stones. The decimal part, multiplied by 14, gives you the remaining pounds. Example: 70 kg ÷ 6.35 = 11.02 st ? 11 st and 0.02 × 14 = 0.3 lb.
Why does the UK use stones for body weight?
Although the UK officially uses the metric system, stones remain popular for personal weight due to cultural tradition. Medical records typically use kilograms, but many people still think of their weight in stones.
What is the average weight of an adult in stones?
The average adult weight varies by country and gender. In the UK, adult men average about 13 stone 3 lb (84 kg) and women about 11 stone (70 kg).
What weight class am I in boxing or MMA?
Boxing and MMA use weight classes based on upper limits. Common divisions include: Flyweight (up to 56.7 kg / 8 st 13 lb), Lightweight (up to 70.3 kg / 11 st 1 lb), Welterweight (up to 77.1 kg / 12 st 2 lb), Middleweight (up to 83.9 kg / 13 st 3 lb), and Heavyweight (over 93 kg / 14 st 9 lb). Check the table above for all classes.
How should I round for fitness tracking?
For most fitness purposes, round to the nearest 0.5 lb (e.g., 11 st 7.5 lb). For medical records, use the exact value from your scale. NHS and UK doctors may record in kg, but many people prefer stones for personal tracking.
Definitions & Formulas
Definition of kilogram
The kilogram (kg) is the SI unit of mass. It is equal to the mass of the international prototype of the kilogram. This prototype is a platinum-iridium international prototype kept at the International Bureau of Weights and Measures. One kg is approximately equal to 2.2046226218487757 pounds.
Definition of stone
The stone or stone weight (abbreviation: st.) is an English unit of mass now equal to 14 pounds or approximately 6.35029318 kilograms. It was historically used across Europe but is now primarily used in the UK and Ireland for measuring body weight.
Definition of pound
One pound, the international avoirdupois pound, is legally defined as exactly 0.45359237 kilograms.
Kilogram to stones formula
To convert kilograms to stones, divide the weight in kilograms by 6.35029318 (the conversion factor).
Kilogram to pounds formula
To calculate a kilogram value to the corresponding value in pounds, multiply the quantity in kilogram by 2.2046226218487757.
Or equivalently:
About Rounding and Fractions
This calculator is designed for everyday use, not for scientific or laboratory purposes. To make results easier to read and use in daily life, we apply the following simplifications:
- Decimal rounding: Results are rounded to 3 significant digits, which is more than enough for cooking, shipping, or personal weight tracking.
- Fraction approximations: When we display fractions (like "2 1/2 lb"), we only show them if the approximation error is less than 10%. This ensures the fraction is reasonably close to the actual value.
- The ˜ symbol: We use "˜" (approximately equal) instead of "=" to remind you that these are rounded values.
For high-precision scientific calculations, please use specialized tools or the exact conversion factor: 1 kg = 2.20462262185 lb.