How it’s calculated

One pound is defined as exactly 0.45359237 kilograms — the international avoirdupois pound, fixed in 1959 and used for body weight in the US. So:

kilograms = pounds × 0.45359237

Worked example: 200 lb × 0.45359237 = 90.718474 kg, which rounds to 90.72 kg.

In your head: halve the pounds, then take away 10% of that. 200 lb → 100 → 100 − 10 = 90 kg. The exact answer is 90.72 kg, so the shortcut is within about 1%.

Pounds to kilograms chart (100–400 lb)

Common body weights in 5-lb steps, rounded to two decimals.

lb	kg
100 lb	45.36 kg
105 lb	47.63 kg
110 lb	49.90 kg
115 lb	52.16 kg
120 lb	54.43 kg
125 lb	56.70 kg
130 lb	58.97 kg
135 lb	61.23 kg
140 lb	63.50 kg
145 lb	65.77 kg
150 lb	68.04 kg
155 lb	70.31 kg
160 lb	72.57 kg
165 lb	74.84 kg
170 lb	77.11 kg
175 lb	79.38 kg

lb	kg
180 lb	81.65 kg
185 lb	83.91 kg
190 lb	86.18 kg
195 lb	88.45 kg
200 lb	90.72 kg
205 lb	92.99 kg
210 lb	95.25 kg
215 lb	97.52 kg
220 lb	99.79 kg
225 lb	102.06 kg
230 lb	104.33 kg
235 lb	106.59 kg
240 lb	108.86 kg
245 lb	111.13 kg
250 lb	113.40 kg
255 lb	115.67 kg

lb	kg
260 lb	117.93 kg
265 lb	120.20 kg
270 lb	122.47 kg
275 lb	124.74 kg
280 lb	127.01 kg
285 lb	129.27 kg
290 lb	131.54 kg
295 lb	133.81 kg
300 lb	136.08 kg
305 lb	138.35 kg
310 lb	140.61 kg
315 lb	142.88 kg
320 lb	145.15 kg
325 lb	147.42 kg
330 lb	149.69 kg
335 lb	151.95 kg

lb	kg
340 lb	154.22 kg
345 lb	156.49 kg
350 lb	158.76 kg
355 lb	161.03 kg
360 lb	163.29 kg
365 lb	165.56 kg
370 lb	167.83 kg
375 lb	170.10 kg
380 lb	172.37 kg
385 lb	174.63 kg
390 lb	176.90 kg
395 lb	179.17 kg
400 lb	181.44 kg

Smaller amounts

Useful for the size of a change — a week, a month, or the difference between two scales.

lb	kg
0.5 lb	0.23 kg
1 lb	0.45 kg
2 lb	0.91 kg
3 lb	1.36 kg
4 lb	1.81 kg
5 lb	2.27 kg
10 lb	4.54 kg

lb	kg
15 lb	6.80 kg
20 lb	9.07 kg
25 lb	11.34 kg
30 lb	13.61 kg
40 lb	18.14 kg
50 lb	22.68 kg

Frequently asked questions

How many kg is 1 lb?

Exactly 0.45359237 kg — about 0.45 kg, or roughly 454 grams. That’s a little under half a kilo.

How do I convert lbs to kg in my head?

Divide by 2.2. Or halve the number and subtract 10% of the result: 180 lb → 90 → 90 − 9 = 81 kg (the exact answer is 81.65 kg).

Why is “pound” abbreviated “lb”?

It comes from the Latin libra, a Roman unit of weight. “lbs” is an informal plural; both mean the same avoirdupois pound.

Why does my weight look so different in kilograms?

It’s the same weight in a different unit. A kilogram is about 2.2 times a pound, so the number in kg is always smaller — a 10-lb change is about 4.5 kg.

Should I track my weight in lb or kg?

Whichever your scale shows — using the same unit, scale and time of day matters more than which unit it is. If you need both, the kg to lbs converter works the other way round.

Informational only, not medical advice. These calculators do simple arithmetic on the numbers you enter. They don’t diagnose anything and don’t replace your clinician or dietitian. Nothing you type is sent anywhere — it stays in your browser. Updated September 2026.

Lbs to kg converter