Pounds to Kilograms
Convert weight between pounds and kilograms.
1 lb = 0.45359237 kg (international avoirdupois pound).
How pounds ↔ kilograms conversion works
Body weight, shipping weights, and grocery labels often switch between pounds (lb) and kilograms (kg). This converter uses the international avoirdupois pound: 1 lb = 0.45359237 kg exactly. That is the standard factor used in science and everyday trade conversions in most countries that still display pounds alongside metric units.
In the UK and Europe, kilograms are the default on scales, airline tickets, and food packaging. Pounds still appear on US fitness apps, some older UK conversations (alongside stone), and imported product labels. Convert with the full factor first, then round once to the precision your form or carrier requires.
Formulas (both directions)
- Pounds → kilograms: kilograms = pounds × 0.45359237
- Kilograms → pounds: pounds = kilograms ÷ 0.45359237
- Rough check: 1 kg ≈ 2.20462 lb (often rounded to 2.2 for casual chat only)
Edit either field; the other updates automatically so you can start from the unit printed on a scale, bag tag, or form.
Worked examples: pounds to kilograms
| Pounds | Kilograms | Typical use |
|---|---|---|
| 1 lb | 0.454 kg | Definition check |
| 50 lb | 22.680 kg | Checked bag near many limits |
| 150 lb | 68.039 kg | Common adult reference on US forms |
| 180 lb | 81.647 kg | Fitness tracking |
| 200 lb | 90.718 kg | Shipping / gym |
Worked examples: kilograms to pounds
| Kilograms | Pounds (approx.) | Typical use |
|---|---|---|
| 1 kg | 2.205 lb | Grocery / mental math |
| 23 kg | 50.706 lb | Common airline checked-bag limit |
| 25 kg | 55.116 lb | Suitcase planning |
| 70 kg | 154.324 lb | Adult body weight |
| 100 kg | 220.462 lb | Shipping / gym plates |
UK stone (optional intermediate step)
In UK conversation, body weight is sometimes stated in stone (st), where 1 stone = 14 lb. This page does not convert stone as a primary unit. Workflow:
- Convert stone to pounds (stone × 14, then add leftover pounds).
- Enter total pounds above to get kilograms.
- Or convert kg → lb here, then divide by 14 for stone (and use the remainder as pounds).
Example: 11 st 4 lb → (11 × 14) + 4 = 158 lb → 158 × 0.45359237 ≈ 71.67 kg.
Quick reference table
| lb | kg | kg | lb |
|---|---|---|---|
| 50 | 22.68 | 10 | 22.05 |
| 100 | 45.36 | 50 | 110.23 |
| 140 | 63.50 | 60 | 132.28 |
| 160 | 72.57 | 80 | 176.37 |
| 220 | 99.79 | 90 | 198.42 |
When each unit is used
- Kilograms — UK/EU scales, most airline baggage rules outside the US, food packaging, and metric medical forms.
- Pounds — US body weight, many US shipping labels, and some fitness equipment plates.
- Stone — Informal UK body-weight conversation; convert via pounds as above.
Practical scenarios
Airline baggage. If your ticket allows 23 kg and your US scale reads pounds, convert the limit once: 23 ÷ 0.45359237 ≈ 50.71 lb. Weigh the bag in pounds against that limit (or switch the scale to kg). Do not use “about 50 lb” as exact if you are near the limit — a kilogram or two of margin is safer than arguing with the desk.
Fitness tracking. Apps may default to lb or kg by region. Pick one unit for logging and stick to it. If you must switch, convert historical entries once with the full factor so week-to-week trends stay comparable.
Shipping and postage. Carriers bill by the unit on the rate card. Convert the package weight into that unit, then round the way the carrier instructs (often up to the next 0.1 kg or 1 lb). Converting a rounded label weight back and forth can push you into the next price band incorrectly.
Tips for scales and travel
Bathroom scales and gym plates may round differently from this exact factor. For medical or legal contexts, use the precision your form requires. Airline baggage: convert the limit once, then weigh in the same unit the carrier states on your ticket. Dual-unit scales can silently switch units — check the indicator before you trust a reading.
How to use it
- Enter weight in pounds or kilograms.
- Read the converted value in the other field.
- Round only when you present the number (labels often use one decimal).
Common mistakes
- Confusing pounds with kilograms on a dual-unit scale (always check the unit indicator).
- Using troy pounds (precious metals) — this page is avoirdupois only.
- Treating “2.2 lb per kg” as exact for shipping declarations.
- Converting a rounded result back and forth, which accumulates display error.
- Forgetting that stone needs the ×14 step before this converter.
Decision checklist
- Is the weight troy (gold/silver)? → Do not use this page.
- Do I have stone + pounds? → Convert to total pounds first.
- Do I have ounces only? → Divide by 16 to get pounds, then convert.
- Is this an airline limit? → Match the unit printed on the ticket after one careful conversion.
Frequently asked questions
Is 2.2 lb per kg exact enough?
For rough estimates, yes. For shipping declarations and many medical forms, prefer the full factor (0.45359237) and then round once.
Does this convert ounces?
Not by itself. There are 16 avoirdupois ounces in a pound — convert ounces to pounds first (ounces ÷ 16), then use this tool.
Why do fitness apps disagree by a tenth of a kilo?
Most round for display. Small differences usually come from rounding, not from a different definition of the pound.
Limitations
Does not convert ounces alone, stones as a primary unit, or troy pounds used for precious metals. For a broader unit overview, see our metric and imperial conversions guide.