Weight and mass converter

How it works

The converter uses gram as the base unit. Every input unit is first converted to grams using its exact definition, then the result is divided by the target unit’s gram equivalent.

For example, 1 kilogram = 1,000 grams; 1 pound = 453.59237 grams (the exact NIST definition). So 5 kg = 5,000 g ÷ 453.59237 = 11.0231 lb.

Unit reference

Worked examples

Body weight — 150 lb

• 150 × 453.59237 = 68,038.86 g = 68.04 kg
• 150 ÷ 14 = 10.71 stone (10 st 10 lb)
• 150 × 16 = 2,400 oz

Shipping — a 5 kg package

• 5 × 1,000 = 5,000 g
• 5,000 ÷ 453.59237 = 11.02 lb
• 11.02 × 16 = 176.37 oz
• In metric tons: 0.005 t

Industrial scale — 1 metric ton of cargo

• 1 tonne = 2,204.62 lb
• 1 tonne = 1.1023 US short tons
• 1 tonne = 0.9842 long tons (UK)

Notes

• “Weight” vs. “mass” — in everyday use they’re interchangeable, but physically mass is the amount of matter (kg), and weight is the force gravity exerts on it (newtons). On the Moon your mass is the same but you weigh about 1/6 as much. All the units here are mass units despite the label.
• Three kinds of “ton” — US short ton (2,000 lb), long ton (2,240 lb, still common in UK), metric ton / tonne (1,000 kg ≈ 2,205 lb). They differ by up to 12%, which matters for shipping quotes and freight rates.
• Avoirdupois vs. troy — the ounces and pounds above are avoirdupois (everyday use). Troy ounces, used for precious metals, are different: 1 troy oz = 31.1 g (heavier than a regular ounce). A “pound of gold” at the jeweler’s is not the same as a pound of flour.
• Conversion factors follow NIST definitions; 1 lb = 453.59237 g exactly.