Pounds and Ounces to Kilograms — Decimal Pounds, Stones and Metric Tons

The one number to remember

One pound is exactly 0.45359237 kilograms. That definition has been fixed by international agreement since 1959, so every pound-to-kilogram conversion is a single multiplication. One ounce is 1/16 of a pound, which makes it 28.349523125 grams.

If you only need a rough figure, divide pounds by 2.2: 150 lb ÷ 2.2 ≈ 68.2 kg (the exact answer is 68.04 kg). For anything you will write down — a medical form, a shipping label, a gym log — multiply by 0.4536 instead.

Decimal pounds vs pounds and ounces

This is the mistake behind a lot of wrong answers. A scale or app that shows 1.5 lb means one and a half pounds — 1 lb 8 oz — not 1 lb 5 oz. The part after the decimal point is a fraction of a pound, and a pound has 16 ounces, not 10.

1.5 lb = 1 lb 8 oz = 0.680 kg. 1.25 lb = 1 lb 4 oz = 0.567 kg. 1.6 lb = 1 lb 9.6 oz = 0.726 kg. 2.34 lb = 2 lb 5.44 oz = 1.061 kg.

Going the other way, 1 lb 5 oz is 1 + 5/16 = 1.3125 lb, which is 0.595 kg. Mixing the two up costs about 85 grams on that example — enough to matter for a recipe, a postage band or a baby's weight.

How to convert pounds and ounces to kg, step by step

Step 1: turn the ounces into a fraction of a pound by dividing by 16. Step 2: add the whole pounds. Step 3: multiply by 0.45359237.

Example: a newborn weighing 7 lb 8 oz. 8 ÷ 16 = 0.5, so the weight is 7.5 lb. 7.5 × 0.45359237 = 3.402 kg, usually written 3.40 kg or 3,402 g.

Example: 8 lb 4 oz. 4 ÷ 16 = 0.25, so 8.25 lb × 0.45359237 = 3.742 kg. Example: 6 lb 15 oz. 15 ÷ 16 = 0.9375, so 6.9375 lb = 3.147 kg.

Shortcut for grams: convert the pounds and the ounces separately and add them. 7 lb = 3,175.1 g and 8 oz = 226.8 g, total 3,401.9 g. Same answer, and easier to check in your head.

Stones, pounds and kilograms

In the UK and Ireland body weight is often given in stones and pounds. One stone is 14 pounds, which is 6.35029318 kg.

Multiply the stones by 14, add the leftover pounds, then convert. 11 st 4 lb = 11 × 14 + 4 = 158 lb, and 158 × 0.45359237 = 71.67 kg. 9 st 0 lb is 126 lb = 57.15 kg.

The weight converter accepts stones directly, so you can type 11.29 st or pick st and lb separately rather than doing the multiplication.

Body-weight examples worked out

119.2 lb = 54.07 kg · 142.8 lb = 64.77 kg · 150 lb = 68.04 kg · 167.5 lb = 75.98 kg.

Notice that these decimals are tenths of a pound from a digital scale, not ounces. 142.8 lb is 142 lb and 0.8 × 16 = 12.8 oz.

Doctors' offices in the US often record weight in pounds and convert to kilograms for medication dosing, which is weight-based. If you are copying a figure across, use at least two decimals in kilograms and keep the original pounds value next to it.

Heavy loads: pounds to kilograms and metric tons

For vehicles, freight and equipment, convert to kilograms the same way, then divide by 1,000 to get metric tons (tonnes). One metric ton is 1,000 kg, which is 2,204.62 lb.

3,300 lb = 1,496.9 kg = 1.497 t · 4,100 lb = 1,859.7 kg = 1.86 t · 5,000 lb = 2,268 kg = 2.268 t · 10,000 lb = 4,535.9 kg = 4.536 t · 12,000 lb = 5,443.1 kg = 5.443 t.

Bigger still: 26,000 lb (a common US threshold for a commercial driver's licence, by gross vehicle weight) is 11,793.4 kg, about 11.8 t. 80,000 lb, the standard US federal gross weight limit for a tractor-trailer on the Interstate system, is 36,287.4 kg, about 36.3 t.

Short tons, long tons and metric tons

"Ton" means three different weights. A US short ton is 2,000 lb = 907.2 kg. A UK long ton is 2,240 lb = 1,016 kg. A metric ton (tonne) is 1,000 kg = 2,204.62 lb.

So a 2-ton US truck rating is about 1.81 metric tons, while a 2-tonne European rating is about 4,409 lb. When a spec sheet just says "tons", check the country it came from before you convert.

Rounding and spreadsheets

Keep the full 0.45359237 factor in a spreadsheet and round only the displayed result. In Excel or Google Sheets, =A2*0.45359237 gives kilograms and =A2*0.45359237/1000 gives metric tons. For pounds and ounces in two columns, use =(A2+B2/16)*0.45359237.

Round body weights to 0.1 kg, baby weights to the gram or 0.01 kg, and freight to the kilogram. Round once, at the end, so small errors do not add up across a long list.