Weight Converter Calculator
Weight Units at a Glance
Two parallel systems are used for measuring body weight around the world — the metric system and the imperial system. Understanding the relationship between units in each system avoids conversion errors in clinical, nutritional, and everyday contexts.
Exact Conversion Factors
All conversions use exact SI-defined values. The kilogram is the SI base unit of mass. The pound is defined as exactly 0.45359237 kg since the 1959 international agreement — all other imperial weight conversions derive from this single definition.
| From | To kg | To g | To lb | To oz |
|---|---|---|---|---|
| 1 microgram (mcg) | 0.000 000 001 | 0.000 001 | 0.000 000 0022 | 0.000 000 035 |
| 1 milligram (mg) | 0.000 001 | 0.001 | 0.000 0022 | 0.000 035 |
| 1 gram (g) | 0.001 | 1 | 0.002205 | 0.035274 |
| 1 kilogram (kg) | 1 | 1,000 | 2.20462 | 35.274 |
| 1 ounce (oz) | 0.028350 | 28.350 | 0.0625 | 1 |
| 1 pound (lb) | 0.453592 | 453.592 | 1 | 16 |
| 1 stone (st) | 6.35029 | 6,350.29 | 14 | 224 |
| 1 metric ton (t) | 1,000 | 1,000,000 | 2,204.62 | 35,274 |
| 1 US short ton | 907.185 | 907,185 | 2,000 | 32,000 |
Common Body Weight Conversions
| Kilograms | Pounds | Stones & lb | Ounces |
|---|---|---|---|
| 40 kg | 88.2 lb | 6 st 4 lb | 1,411 oz |
| 45 kg | 99.2 lb | 7 st 1 lb | 1,587 oz |
| 50 kg | 110.2 lb | 7 st 12 lb | 1,764 oz |
| 55 kg | 121.3 lb | 8 st 9 lb | 1,940 oz |
| 60 kg | 132.3 lb | 9 st 6 lb | 2,116 oz |
| 65 kg | 143.3 lb | 10 st 3 lb | 2,293 oz |
| 70 kg | 154.3 lb | 11 st 0 lb | 2,469 oz |
| 75 kg | 165.3 lb | 11 st 11 lb | 2,646 oz |
| 80 kg | 176.4 lb | 12 st 8 lb | 2,822 oz |
| 90 kg | 198.4 lb | 14 st 2 lb | 3,175 oz |
| 100 kg | 220.5 lb | 15 st 10 lb | 3,527 oz |
Frequently Asked Questions
How do I convert kg to pounds?
Multiply kilograms by 2.20462. For example, 70 kg × 2.20462 = 154.32 lb. For a quick mental approximation, multiplying by 2.2 gives a result accurate to within 0.2% — close enough for most everyday purposes. To go the other direction, divide pounds by 2.20462 (or multiply by 0.453592) to get kilograms.
What is a stone in kg and pounds?
One stone equals exactly 14 pounds or approximately 6.35 kg. To convert stones to kilograms, multiply by 6.35029. For example, 11 stone equals 11 × 6.35029 = 69.85 kg. To express a weight in stones and pounds, divide the total pounds by 14 — the whole number is the stones, and the remainder is the additional pounds. So 154 lb ÷ 14 = 11 stone with 0 lb remaining, or exactly 11 stone.
How many grams are in a pound?
Exactly 453.59237 grams — derived from the internationally agreed definition that 1 pound equals exactly 0.45359237 kilograms, and 1 kilogram equals 1,000 grams. This is an exact definition, not an approximation, established by the 1959 international agreement between English-speaking countries' national standards laboratories.
Why do some countries use kg and others use pounds?
Most countries have officially adopted the metric system and use kilograms for body weight in medical and everyday contexts. The United States is the primary exception, using pounds for everyday body weight while using kilograms in most scientific and medical applications. The United Kingdom uses a mix — kilograms in NHS clinical settings, but stones and pounds remain dominant in everyday British conversation about body weight. Australia, Canada, and most of Europe use kilograms exclusively.
What is the difference between weight and mass?
Technically, mass is the amount of matter in an object (measured in kilograms) and weight is the force of gravity acting on that mass (measured in newtons). In everyday language and in this calculator, "weight" and "mass" are used interchangeably — which is acceptable because on Earth's surface, gravitational acceleration is effectively constant, so mass and weight measurements are directly proportional. The distinction matters in physics and space science but not in everyday clinical or nutritional contexts.
