Imperial to Metric Converter

1. Choose the measurement: length, weight, volume, area, temperature or speed.
2. Pick the imperial or US unit you have and the metric unit you want. For liquids, choose US or UK on purpose.
3. Type the value. For feet, pounds or stone, add the second part too, such as 5 ft 10 in or 7 lb 8 oz.

Here is what each result means:

Imperial to metric conversion turns inch-pound measurements, such as feet, pounds and gallons, into SI units such as meters, kilograms and liters. The answer is a multiplication, because every inch-pound unit is now defined as a fixed metric amount.

"Imperial" is often used for two related systems. The UK imperial system is set out in Schedule 1 of the Weights and Measures Act 1985. US customary units are tabled in NIST Handbook 44, Appendix C. NIST notes that the yard and the avoirdupois pound are identical in both. Their liquid measures are not: the UK gallon is 4.54609 L, while the US gallon is 231 cubic inches, or 3.785411784 L.

People use this direction most for school and science work, which is metric, and for official forms, recipes and building supplies from abroad. To go the other way, from metric units back to inches, pounds and gallons, use the metric to imperial converter.

You multiply the imperial amount by the metric size of one unit. No division is needed in this direction.

1. Look up the defined size. One foot is exactly 0.3048 m, so it is 30.48 cm.
2. Add any second part first. 5 ft 10 in is 5 + 10/12 = 5.8333 ft, or 70 in.
3. Multiply. 70 in x 2.54 cm = 177.8 cm. Round only after this step.

Because the yard, pound and UK gallon are exact metric decimals, almost every imperial to metric factor ends after a few digits. The knot to meters per second factor, 1,852/3,600, is the rare one that repeats.

Height for a form. 5 ft 10 in is 70 in. 70 x 2.54 = 177.8 cm, or 1.778 m.

Newborn weight. 7 lb 8 oz is 7.5 lb. 7.5 x 0.45359237 = 3.402 kg, or 3,401.9 g.

UK body weight. 12 st 6 lb is 174 lb. 174 x 0.45359237 = 78.93 kg.

A pint of milk. One UK pint is 568.26 mL. One US pint is 473.18 mL. The UK pint holds 95.08 mL more.

Oven setting. 350 F: (350 - 32) / 1.8 = 176.7 C. Many metric recipes round this to 180 C.

Floor area. 2,000 sq ft x 0.09290304 = 185.81 sq m. A quick guess, dividing by 10.76, gives 185.87 sq m.

US and UK liquid units share names but not sizes. The UK pint, quart and gallon are 20.1 percent larger. Yet the UK fluid ounce is 3.9 percent smaller, because a UK pint holds 20 fluid ounces and a US pint holds 16.

NIST Handbook 44 puts it plainly: the Imperial gallon is about 20 percent larger than the US gallon. Fuel prices, car fuel economy and drink sizes all shift by that fifth. For single fluid ounce jobs, the fluid ounces to mL converter is a one-field shortcut.

Common values, computed from the exact factors and rounded for reading.

The factors are fixed, so the result changes only with the unit version you pick and how you round.

US or UK Liquid Units

A gallon of fuel is 3.785 L in the US and 4.546 L in the UK. Picking the wrong one moves the answer by about a fifth.

Liquid vs Dry Pints

The US also has a dry pint of 33.6003125 cubic inches, which is 550.61 mL, for berries and grain. This tool uses the US liquid pint of 473.18 mL.

Avoirdupois vs Troy Ounces

Food and parcels use the 28.35 g ounce. Gold and silver use the troy ounce of 31.1034768 g, which the UK Act also defines. The troy ounce is 9.7 percent heavier.

Old Survey Units

US land surveys once used a slightly longer survey foot, which NIST phased out at the start of 2023. Acres on old US land records differ from the international acre by about 4 parts per million, far below everyday rounding.

Where You Round

Rounding 1 lb to 0.45 kg before multiplying puts 150 lb at 67.5 kg instead of 68.04 kg. Keep the full factor and round the final answer.

School, Lab and Science Work

Science classes and labs record data in SI units. A 12 in ruler reading becomes 30.48 cm, and a 3 lb sample becomes 1.361 kg.

US Recipes in a Metric Kitchen

A US recipe asks for 2 cups of milk. That is 473.18 mL. For flour or sugar by the cup, you need density, so use the baking conversion calculator or the cups to mL converter for liquids.

DIY and Building Supplies

A plan in feet meets timber and tile sold in millimeters. An 8 ft board is 2,438.4 mm. For many lengths at once, the feet to meters converter is quicker.

Travel and Moving Abroad

Forms and health records in metric countries usually ask for height in cm and weight in kg. The second-part field turns 5 ft 10 in or 12 st 6 lb into one metric number.

1. Reading 5.10 Ft as 5 Ft 10 In

5.10 ft is 5 ft 1.2 in, or 155.45 cm. 5 ft 10 in is 177.8 cm. Enter the inches in the second field.

2. Using a UK Gallon for a US Figure

A 15 gallon US tank is 56.78 L. Treated as UK gallons, it becomes 68.19 L, which is 20 percent too much.

3. Converting an Ounce of Liquid by Weight

A fluid ounce is volume and an ounce is mass. 8 US fl oz of water is 236.6 mL, but 8 oz on a scale is 226.8 g.

4. Forgetting the 32 in Fahrenheit

350 F / 1.8 gives 194.4, not the true 176.7 C. Subtract 32 first.

5. Converting a Temperature Change with the Full Formula

A 10 F rise is a 5.56 C rise. Temperature differences use only the 1.8 factor.

6. Squaring the Wrong Factor for Area

1 sq ft is 0.3048 x 0.3048 = 0.09290304 sq m, not 0.3048 sq m. Area factors are the length factor squared.

The results are as exact as the legal definitions, and nearly every factor here ends after a few digits.

5 feet 10 inches is 177.8 cm. It is 70 inches, and each inch is exactly 2.54 cm.

Multiply the pounds by 0.45359237. For example, 150 lb is 68.04 kg. Halving and taking off a tenth, 0.45, is a close guess.

12 stone is 76.20 kg. One stone is 14 lb, and 14 x 0.45359237 gives 6.35029318 kg per stone.

A UK gallon is exactly 4.54609 L. A US gallon is exactly 3.785411784 L, which is 231 cubic inches.

A US cup is 236.5882365 mL. It is half a US pint, or 8 US fluid ounces.

350 F is 176.7 C. Subtract 32, then divide by 1.8. Metric recipes often round it to 180 C.

1,000 sq ft is 92.90 sq m. Each square foot is 0.09290304 sq m.

One acre is 0.4047 hectares, or 4,046.8564224 sq m. An acre is 4,840 square yards.

Since 1959, the yard and pound have been defined in metric terms. The UK Act of 1985 also fixes the gallon at 4.54609 L, so the factors are set by law.

Divide the change by 1.8 and skip the 32. A rise of 10 F is a rise of 5.56 C.

No. Cups measure volume and grams measure mass, so you need the density of each ingredient. Use a baking conversion tool for that.

No. The math runs on your own device and no value leaves the page. Saved results sit in this browser only, and Clear all removes them.

• US customary tables and notes on British units, including the Imperial gallon (NIST Handbook 44, 2026, Appendix C).
• Exact conversion factors for inch, foot, mile, pound, ounce and gallon (NIST SP 811, Appendix B.8).
• Fahrenheit to Celsius and kelvin formulas (NIST SP 811, Appendix B.9).
• UK imperial definitions: yard, pound, stone, gallon, pint and fluid ounce (Weights and Measures Act 1985, Schedule 1, legislation.gov.uk).
• The US survey foot and its retirement in 2023 (NIST Office of Weights and Measures).