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Weight Converter — Calculadora

LIVE
Pound (lb)
2.204623
1 Kilogram (kg)

Convert kilograms, pounds, stones, ounces and tonnes with UK-friendly defaults — the UK still uses stones for body weight and pounds at the deli counter.

Written by Editorial DeskReviewed by Laura Whitmore

How it works

Why the UK still uses stones

A practical weight converter has to understand stones (14 lb each) because NHS leaflets, gym goals and pub conversations still quote “12 stone 4” rather than 78 kg. Our tool converts whole stones + pounds to kg in one step and back again for talking to EU suppliers.

Exact factors you should know

  • 1 kg = 2.204 622 621 85 lb (NIST)
  • 1 stone = 14 lb = 6.350 293 18 kg
  • 1 oz (avoirdupois) = 28.349 523 125 g — not the same as a fluid ounce of water
  • 1 tonne (metric) = 1 000 kg ≈ 0.984 long tons (UK shipping still quotes both)

Three worked examples

NHS target — lose 5 kg

5 kg × 2.20462 ≈ 11.0 lb ≈ 0.79 stone — clearer for patients who think in stones.

Parcel limit — 30 kg airline baggage

30 × 2.20462 ≈ 66.1 lb. Ryanair limits are often quoted in kg; US carriers in lb — convert before you pack.

Recipe — 12 oz flour

12 × 28.35 g ≈ 340 g. Cross-check with our **grams to cups** tool for baking tins.

Mass vs weight in everyday language

Physicists distinguish mass (kg) from weight (newtons), but everyday UK English says “weight” for both. Medical and trading law use mass in kg; that is what this converter computes.

Works well with

Sources

Factors trace to the SI Brochure (BIPM) and NIST. See editorial policy and corrections.

Frequently asked questions

How many pounds in a stone?
Exactly 14 avoirdupois pounds.
How do I convert kg to stone and pounds?
Divide kg by 6.35029318 to get stones (decimal). The fractional part × 14 gives the remaining pounds.
Is a US ton the same as a UK ton?
No — a US ton is 2000 lb (short ton). A UK long ton is 2240 lb. Tonnes in metric are 1000 kg.
Why is my bathroom scale different from the GP scale?
Calibration, floor surface and time of day vary by 1–2 kg. Use the same scale, same time, weekly averages.
Are ounces the same in UK and US?
For mass, yes — both use the avoirdupois ounce (28.35 g). Fluid ounces are volume, not mass.
Can I convert grams to micrograms?
Yes — multiply or divide by powers of ten; our tool keeps full precision with decimal.js internally.
What is a “metric stone”?
Not official — some apps use 10 kg ≈ 1.57 stone as a rough mnemonic, but it is not legal metrology.
Do I need to convert before BMI?
Yes — plug kilograms and metres into the BMI formula, or use our BMI calculadora which handles units.
What about troy ounces for gold?
Different unit (31.1 g). This converter focuses on everyday and medical mass units.
Is data sent to a server?
No — conversions run locally in your browser.

References

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