lbs to kg Converter
Convert pounds to kilograms for fitness, shipping, and international weight comparison.
How It Works
Formula: lbs to kg = value × 0.45359237
Example: 150 lbs = 68.038855 kg
Note: 1 pound equals 0.45359237 kilograms.
Common Uses
Quick Conversion Table
| lbs | kg |
|---|---|
| 1 | 0.4536 |
| 5 | 2.268 |
| 10 | 4.5359 |
| 25 | 11.3398 |
| 50 | 22.6796 |
| 100 | 45.3592 |
| 150 | 68.0389 |
| 200 | 90.7185 |
Rounding Rule
Rounded to 6 decimal places
Error Margin
±0.00001 kg
Precision Guidance
For everyday use, round to 2 decimal places.
Common Mistakes
Do not confuse with troy pounds used for precious metals.
Frequently Asked Questions
What is 1 lb in kg?
1 pound equals 0.45359237 kilograms using the US avoirdupois standard.
How do I convert lbs to kg?
Multiply the pound value by 0.45359237. For example, 150 lbs × 0.45359237 = 68.04 kg.
How many kg is 120 lbs?
120 pounds equals 54.431 kilograms (120 × 0.45359237 = 54.4311 kg).
How many kg is 150 lbs?
150 pounds equals 68.039 kilograms (150 × 0.45359237 = 68.0389 kg).
How many kg is 180 lbs?
180 pounds equals 81.647 kilograms (180 × 0.45359237 = 81.6466 kg).
How many kg is 200 lbs?
200 pounds equals 90.718 kilograms (200 × 0.45359237 = 90.7185 kg).
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 pound (lb, avoirdupois) = 0.45359237 kilograms (exact)
- EXACT1 ounce (oz, avoirdupois) = 28.349523125 grams (exact, 1/16 lb)
- EXACT1 stone (st) = 6.35029318 kilograms (exact, 14 lb)
- EXACT1 short ton (US) = 907.18474 kilograms (exact, 2000 lb)
Common Pitfalls & How to Avoid Them
Mass vs. weight
The pound and kilogram are units of MASS, not force. On Earth, mass and "weight" read the same number in practice, but a 70 kg mass weighs less on the Moon. UnitFig converts mass; for scientific force you need newtons (1 lbf = 4.4482216152605 N, exact).
Avoirdupois vs. troy ounce
Cooking and body weight use the avoirdupois ounce (28.349523125 g). Gold and precious metals use the troy ounce (31.1034768 g). Never mix them — the error is about 10%.
Rounding the factor
Using 2.2 instead of the exact 2.20462262 overstates small errors at large values. For medical dosing or competition weight classes, keep the full factor or use a converter.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
Last Updated 2026 | This converter was reviewed for accuracy