Length Converter
Length conversions most commonly involve switching between the metric system (millimetres, centimetres, metres, kilometres) and the imperial system (inches, feet, yards, miles). The metric system is the international standard, used in most countries. The imperial system is used primarily in the United States, with some units still in everyday use in the UK.
Key definitions: one inch is defined as exactly 25.4 millimetres by international agreement since 1959. One mile equals exactly 1,609.344 metres. One foot equals exactly 12 inches or 30.48 centimetres.
Weight Converter
The kilogram (kg) is the SI base unit of mass, used in most countries. One pound is defined as exactly 0.45359237 kilograms. The stone is used primarily in the UK and Ireland for measuring body weight — one stone equals exactly 14 pounds or approximately 6.35 kilograms.
The metric tonne (t) equals 1,000 kilograms, approximately 2,204.6 pounds or 157.5 stone. It differs from the US short ton (2,000 lb) and the UK long ton (2,240 lb).
Temperature Converter
Three temperature scales are in common use. Celsius (°C) is the international standard for everyday use, where water freezes at 0°C and boils at 100°C at standard pressure. Fahrenheit (°F) is used primarily in the United States, where water freezes at 32°F and boils at 212°F. Kelvin (K) is the SI base unit of temperature, used in scientific contexts — it starts at absolute zero (0 K = −273.15°C), the lowest theoretically possible temperature.
The Celsius and Kelvin scales have identical degree intervals, so a temperature difference of 1°C equals a difference of 1 K. Fahrenheit degrees are smaller: a change of 1°C equals a change of 1.8°F.
Volume Converter
Volume measurements vary significantly between countries. The US cup equals 236.59 ml, while the metric cup used in Australia, Canada and New Zealand equals exactly 250 ml. US gallons (3.785 L) are approximately 20% smaller than UK imperial gallons (4.546 L). When following international recipes or comparing fuel economy figures, it is important to confirm which measurement system is in use.
In the metric system, one litre equals exactly 1,000 millilitres and one litre of water weighs approximately one kilogram at standard conditions.
Speed Converter
Speed is measured in different units depending on context. Kilometres per hour (km/h) is the metric standard for road speeds in most countries. Miles per hour (mph) is used in the United States and United Kingdom. Metres per second (m/s) is the SI unit of speed, used in scientific and engineering contexts. Knots (nautical miles per hour) are used in maritime navigation and aviation worldwide.
Key equivalences: one knot equals exactly 1.852 km/h by international definition. The speed of sound in dry air at 20°C is approximately 343 m/s (1,235 km/h or 767 mph).
Area Converter
Area units differ between scientific, agricultural and real estate contexts. The hectare (ha) is the international standard for measuring land area — one hectare is defined as exactly 10,000 square metres, equivalent to a square plot 100m × 100m. Hectares are used in most countries for agriculture, property and geography.
Acres are used in the United States, United Kingdom and some other countries, particularly in real estate. One acre equals 43,560 square feet or approximately 4,047 square metres. One square kilometre contains exactly 100 hectares or approximately 247.1 acres.
Data Storage Converter
Digital storage is measured in bytes and their multiples. One byte equals exactly 8 bits. There are two competing standards for larger units. The binary (IEC) standard — used by operating systems — defines 1 kilobyte as 1,024 bytes, 1 megabyte as 1,024 kilobytes, and so on. The decimal (SI) standard — used by hard drive and SSD manufacturers — defines 1 kilobyte as 1,000 bytes.
This is why a hard drive marketed as "1 TB" typically shows as approximately 931 GB in Windows or macOS: the manufacturer uses decimal (1 TB = 1,000 GB) while the OS uses binary (1 GB = 1,073,741,824 bytes). Internet speeds are measured in bits per second (bps), not bytes — so a 100 Mbps connection transfers approximately 12.5 megabytes per second.
Cooking Measurement Converter
US recipes use volume-based measurements (cups, tablespoons, teaspoons) rather than weight, which can cause confusion when cooking from international sources. One US tablespoon equals exactly 3 teaspoons and approximately 14.79 ml. One US cup equals 16 tablespoons, 48 teaspoons or approximately 236.59 ml.
Note that the metric cup (250 ml) used in Australia, Canada and New Zealand is slightly larger than the US cup (236.59 ml). UK recipes may use imperial fluid ounces (28.41 ml) rather than US fluid ounces (29.57 ml). For precise baking, weighing ingredients in grams is more accurate than volume measures.
About ConvertStuffNow
ConvertStuffNow is a free unit conversion tool built for accuracy and speed. All conversion factors are based on internationally recognised definitions — including SI (International System of Units) standards, the international yard and pound agreement of 1959, and NIST (National Institute of Standards and Technology) reference data.
The tool covers eight conversion categories: length, weight, temperature, volume, speed, area, data storage and cooking measurements — the units people need most in daily life, travel, cooking, study and work. All conversions run entirely in your browser. No data is sent to any server, and no account or app is required.
ConvertStuffNow is designed to give you the exact answer as quickly as possible, with the formula shown so you can verify or repeat the calculation yourself.
Frequently Asked Questions
How many cm in an inch?
There are exactly 2.54 centimetres in one inch. The inch was redefined in 1959 by international agreement as exactly 25.4 mm. To convert inches to centimetres, multiply by 2.54. For example, 5 inches = 12.7 cm. Conversely, divide centimetres by 2.54 to get inches.
How do I convert Fahrenheit to Celsius?
To convert Fahrenheit to Celsius, subtract 32, then multiply by 5/9. Formula: °C = (°F − 32) × 5/9. For example, 98.6°F = (98.6 − 32) × 5/9 = 37°C. To go the other way: °F = (°C × 9/5) + 32.
How many ml in a cup?
One US cup equals 236.59 ml. A metric cup (used in Australia, Canada and New Zealand) equals exactly 250 ml. When following international recipes, it is worth checking which cup measure is intended, as the difference adds up in baking.
How many feet in a metre?
One metre equals 3.28084 feet. To convert metres to feet, multiply by 3.28084. To convert feet to metres, multiply by 0.3048. For a quick rough estimate, 1 metre ≈ 3 feet 3 inches.
How many kg in a pound?
One pound equals exactly 0.45359237 kilograms. One kilogram equals 2.20462 pounds. To convert pounds to kg, multiply by 0.4536. A useful shortcut: divide pounds by 2.2 for a quick kg estimate.
How many km/h is 1 mph?
1 mile per hour equals 1.60934 km/h. To convert mph to km/h, multiply by 1.60934. A useful rule of thumb: 60 mph ≈ 96.6 km/h, and 100 km/h ≈ 62.1 mph.
How many GB in a TB?
In binary (as used by operating systems), 1 TB = 1,024 GB. Hard drive manufacturers often use decimal, where 1 TB = 1,000 GB. This is why a 1 TB drive shows as approximately 931 GB in your OS.
How many tablespoons in a cup?
There are 16 tablespoons in one US cup. One tablespoon equals 3 teaspoons and approximately 14.79 ml. Half a cup = 8 tablespoons; a quarter cup = 4 tablespoons.
How many acres in a hectare?
One hectare equals 2.47105 acres. A hectare is 10,000 m² (a square 100m × 100m). An acre is approximately 4,047 m² or 43,560 square feet. Hectares are used in most countries; acres are common in the US and UK.
How many litres in a gallon?
One US gallon equals 3.78541 litres. One imperial (UK) gallon equals 4.54609 litres. US gallons are approximately 20% smaller than UK gallons, which matters when comparing fuel economy figures across countries.
What is absolute zero in Celsius and Fahrenheit?
Absolute zero is −273.15°C or −459.67°F. It is the theoretical lowest possible temperature, at which atoms have minimum thermal motion. On the Kelvin scale, absolute zero is 0 K — the starting point of the scale.
How many ounces in a pound?
One pound (lb) equals 16 ounces (oz) in the avoirdupois system used for everyday weight measurement. To convert pounds to ounces, multiply by 16. One ounce equals 28.3495 grams, so one pound equals approximately 453.59 grams.
What is a knot in speed?
A knot is one nautical mile per hour. One knot equals exactly 1.852 km/h or approximately 1.151 mph. Knots are the international standard unit of speed for maritime navigation and aviation.
How many grams in an ounce?
One ounce equals 28.3495 grams. To convert ounces to grams, multiply by 28.3495. There are 16 ounces in one pound, which equals approximately 453.59 grams.
What is a stone in weight?
A stone is a unit of weight equal to 14 pounds or approximately 6.35 kilograms. The stone (st) is used primarily in the United Kingdom and Ireland for measuring body weight. It is not used in most other countries.
How many miles in a kilometre?
One kilometre equals 0.621371 miles. One mile equals 1.60934 kilometres. A useful rough conversion: 8 km ≈ 5 miles, or 5 miles ≈ 8 km.
What is the difference between a US gallon and a UK gallon?
A US gallon equals 3.78541 litres. A UK imperial gallon equals 4.54609 litres, making it approximately 20% larger. This matters when comparing fuel economy: a car described as achieving 40 mpg on US gallons performs differently to one achieving 40 mpg on UK gallons.
How do you convert Celsius to Kelvin?
To convert Celsius to Kelvin, add 273.15. Formula: K = °C + 273.15. For example, 0°C = 273.15 K and 100°C = 373.15 K. The Kelvin and Celsius scales have identical degree intervals — Kelvin starts at absolute zero rather than the freezing point of water.
What is the difference between bits and bytes?
A bit is the smallest unit of digital information, with a value of either 0 or 1. A byte equals 8 bits and can represent 256 different values. Storage capacity (files, drives, memory) is measured in bytes — KB, MB, GB, TB. Internet and network speeds are measured in bits per second (Mbps, Gbps), so a 100 Mbps connection transfers approximately 12.5 megabytes per second.
How many square feet in an acre?
One acre equals 43,560 square feet. This is equivalent to a square plot approximately 208.7 feet (63.6 m) on each side. One acre also equals approximately 4,047 square metres or 0.4047 hectares.
How do I convert square metres to square feet?
To convert square metres to square feet, multiply by 10.7639. To convert square feet to square metres, multiply by 0.0929. For example, 100 m² = 1,076.39 sq ft, and 1,000 sq ft ≈ 92.9 m².
How many teaspoons in a tablespoon?
One tablespoon equals exactly 3 teaspoons. One US tablespoon is approximately 14.79 ml and one US teaspoon is approximately 4.93 ml. There are 48 teaspoons and 16 tablespoons in one US cup.