What is Weight Conversion?
Mass is measured in the metric system (milligrams, grams, kilograms, metric tons) by most of the world, and in avoirdupois units (ounces, pounds, stones) in the United States and, for body weight, the United Kingdom. Recipes, gym plates, luggage allowances, package shipping, and body weight all hop between these systems — kg to lbs is among the most searched conversions on the web.
What Does This Tool Do?
Enter a weight, choose the source and target units, and the converted value appears instantly, together with a table showing the same weight in all seven supported units. Conversions use the exact definition (1 lb = 0.45359237 kg, fixed by international agreement in 1959), so the math is precise.
How to Use This Tool
- Type the weight value.
- Pick the from and to units — your selection is remembered for next time.
- Read the instant result and the all-units table; copy with one click.
- Use ⇄ to reverse the conversion.
Exact Conversion Factors
| Unit | In kilograms | Common equivalence |
|---|---|---|
| Milligram (mg) | 0.000001 | 1 g = 1,000 mg |
| Gram (g) | 0.001 | 1 oz ≈ 28.35 g |
| Kilogram (kg) | 1 | 1 kg ≈ 2.205 lb |
| Metric ton (t) | 1,000 | 1 t ≈ 2,205 lb |
| Ounce (oz) | 0.028349523125 | 16 oz = 1 lb |
| Pound (lb) | 0.45359237 | 1 lb ≈ 0.454 kg |
| Stone (st) | 6.35029318 | 1 st = 14 lb |
Mental Math Shortcuts
- kg → lbs: double it and add 10% (80 kg → 160 + 16 = 176 lb; exact: 176.4).
- lbs → kg: divide by 2 and take off 10% (150 lb → 75 − 7.5 = 67.5 kg; exact: 68.0).
- Stones: UK body weight reads like “11 st 4 lb” — multiply stones by 14, add the pounds, then convert (11×14 + 4 = 158 lb ≈ 71.7 kg).
- Ounces in cooking: 1 oz ≈ 28 g, so a rough “×30 then trim” works for small amounts.
Everyday Reference Weights
| Item | Weight |
|---|---|
| Paper clip | ~1 g |
| AA battery | ~23 g |
| Smartphone | ~180–220 g |
| Soccer ball | ~430 g / ~15 oz |
| Bag of sugar (US) | 4 lb / 1.81 kg |
| Cabin luggage limit (typical) | 8–10 kg / 18–22 lb |
| Checked luggage limit (typical) | 23 kg / 50 lb — the airline classic |
| Adult Labrador | ~30 kg / ~66 lb / ~4.7 st |
Weight vs Mass: a Pedantic but Useful Note
Strictly, kilograms and pounds measure mass, while weight is the force gravity exerts on that mass. On Earth’s surface the distinction rarely matters — your 70 kg is 70 kg everywhere you’ll ever stand — but it explains why scientists say “mass” and why a 70 kg astronaut is weightless yet still very much 70 kg. For everyday conversion purposes, treat them as the same thing, like this tool (and every bathroom scale) does.
Popular Conversions
Dedicated pages with body-weight tables and shortcuts: kg to lbs and lbs to kg.
Frequently Asked Questions
Is my data private?
Yes — everything runs locally in your browser. Nothing you type is transmitted or stored.
Is a pound exactly 0.45359237 kg?
Yes — since 1959 the avoirdupois pound has been defined as exactly 0.45359237 kg, so pound↔kilogram conversions are exact, not approximate.
What's the difference between a metric ton, a US ton, and a UK ton?
The metric ton (tonne) is 1,000 kg. The US “short ton” is 2,000 lb (907.2 kg) and the UK “long ton” is 2,240 lb (1,016 kg). This tool uses the metric ton; if a document just says “ton”, check which country it comes from.
Why do the British weigh people in stones?
Tradition — the stone (14 lb) survived metrication for body weight in everyday UK speech. “12 stone 6” means 12×14 + 6 = 174 lb ≈ 78.9 kg. Convert stones here directly, or via pounds.
Are fluid ounces and ounces the same?
No — the ounce here is weight (~28.35 g), while a fluid ounce is volume (~29.6 mL). Recipes mix them up constantly; for liquids, use our Volume Converter instead.