Weight & mass conversions
Most errors on this page are vocabulary, not arithmetic: a metric tonne is not a US short ton, a troy ounce is not a food ounce, and UK stone often ships with leftover pounds. Every dropdown value routes through the kilogram so the ratios stay aligned.
How the converter works
Each unit has a fixed kilogram equivalent. The tool converts your input to kg, then divides by the target unit's kg factor.
Result = Value × (source unit in kg) ÷ (target unit in kg)
Example: By default, 1 kg becomes 1,000 g (1 ÷ 0.001). For US customary, 5 lb to grams: 5 × 0.453592 ÷ 0.001 ≈ 2,267.96 g. The kg factors cancel; you are left with one ratio.
Units in the dropdown
Factors below match what the calculator uses internally (stored as kg equivalents).
Kilogram (kg)
Factor: 1 (base)
SI base unit of mass since 2019 (defined via Planck's constant). Labs, medicine, and most of the world default here.
Gram (g)
Factor: 0.001 kg
Nutrition labels, recipes, and postage. A 500 g pack is about 1.1 lb, not half a pound.
Milligram (mg)
Factor: 0.000001 kg
Doses and supplement panels. 500 mg is 0.5 g exactly; do not confuse mg columns with grams in CSV imports.
Pound (lb)
Factor: 0.453592 kg
Avoirdupois pound (16 oz). US law fixes 1 lb = 0.45359237 kg; this tool uses the same rounded constant as the focused lb↔kg pages.
Stone (st)
Factor: 6.350288 kg (14 lb)
UK and Ireland body weight. 11 st 4 lb means 11×14 + 4 = 158 lb, not 11.4 stone.
Ounce (oz)
Factor: 0.0283495 kg
Avoirdupois ounce for food and shipping. Troy ounces (bullion) are heavier; this converter does not use them.
Metric ton (t)
Factor: 1,000 kg
Also called a tonne. About 2,204.62 lb, not 2,000 (US short ton) or 2,240 (UK long ton).
Quick reference
Common pairs with the same factors as the calculator. For a single pair with more context, use the focused links at the bottom.
| From | To | Formula | Example |
|---|---|---|---|
| Kilograms | Pounds | kg × 2.20462 | 70 kg = 154.32 lbs |
| Pounds | Kilograms | lbs × 0.453592 | 150 lbs = 68.04 kg |
| Stones | Kilograms | st × 6.35029 | 12 st = 76.20 kg |
| Kilograms | Stones | kg ÷ 6.35029 | 70 kg ≈ 11.02 st |
| Stones | Pounds | st × 14 | 12 st = 168 lbs |
| Pounds | Stones | lbs ÷ 14 | 168 lbs = 12 st |
| Pounds | Ounces | lbs × 16 | 5 lbs = 80 oz |
| Ounces | Pounds | oz ÷ 16 | 32 oz = 2 lbs |
| Ounces | Grams | oz × 28.3495 | 8 oz = 226.80 g |
| Grams | Ounces | g × 0.035274 | 500 g = 17.64 oz |
| Metric Tons | Pounds | t × 2,204.62 | 2 t = 4,409.24 lbs |
| Milligrams | Grams | mg ÷ 1,000 | 500 mg = 0.5 g |
Weight vs mass (when it matters)
Everyday speech mixes the words. In physics, mass is how much matter (kg) and weight is gravitational force (newtons).
Mass
70 kg on Earth is still 70 kg on the Moon. Balances compare unknown mass to known masses.
Weight
That same 70 kg is about 686 N on Earth and ~114 N on the Moon. Spring scales read force, then often display an equivalent mass.
For kitchen, gym, and freight work on Earth, treating scale readings as mass in kg or lb is standard. The distinction shows up in aerospace, geophysics, and formal mechanics.
Why the units look inconsistent
Metric mass grew from the gram (originally tied to water volume) with the kilogram as the practical base. US and UK customary mass stayed on pounds and ounces rooted in trade weights.
The 1959 agreement fixed the avoirdupois pound at 0.45359237 kg, which is why lb↔kg conversions are exact while many displayed decimals are rounded.
Three different "tons" still circulate: US short (2,000 lb), UK long (2,240 lb), and metric (1,000 kg ≈ 2,204.62 lb). Contracts and emissions data usually mean the metric tonne unless the document says otherwise.
Weight conversion FAQ
How many pounds are in a kilogram?
About 2.20462 lb per kg. Example: 70 kg ≈ 154.32 lb. The lb↔kg factor is exact by definition; extra decimals are display rounding.
What's the difference between weight and mass?
Mass is matter (kg, g). Weight is force (newtons). Scales on Earth usually show mass equivalents because local gravity is nearly constant.
How many grams are in an ounce?
One avoirdupois ounce is 28.349523125 g. Troy ounces (31.1035 g) are for bullion, not grocery labels. This tool uses avoirdupois.
How many ounces are in a pound?
There are exactly 16 ounces in 1 pound. Quick checks: 2 pounds = 32 ounces, 5 pounds = 80 ounces, and 10 pounds = 160 ounces.
How many pounds are in an ounce?
One ounce is 0.0625 pounds (1/16 of a pound). To convert ounces to pounds, divide by 16. Example: 40 oz ÷ 16 = 2.5 lbs.
How many grams are in a pound?
One pound is exactly 453.59237 grams. For quick math, many people round to 454 g per pound. Example: 3 lbs ≈ 1,360.78 g.
Metric ton, short ton, or long ton?
This dropdown uses the metric tonne (1,000 kg ≈ 2,204.62 lb). A US short ton is 2,000 lb; a UK long ton is 2,240 lb. Mixing them is a common 10% pricing error.
How do stone and pounds combine?
11 st 4 lb = 11×14 + 4 = 158 lb total. Convert the full pound amount, or use the focused stone pages linked below.