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Unit Converters

Unit converters translate a measurement from one system into another so that a recipe, a spec sheet or an overseas parcel label makes sense. Cooks, students, engineers and anyone reading instructions written for a different country use them constantly. If you already know the type of measurement, go straight to the specific tool. The Length Converter covers millimetres through to miles, the Weight Converter moves between kilograms, pounds, stones and ounces, and the Temperature Converter handles Celsius, Fahrenheit and Kelvin, including the negative values that trip people up. The Volume Converter deals with litres, pints, cups and gallons, and matters most in the kitchen where the American cup and the imperial pint differ. The Speed Converter switches between kilometres per hour, miles per hour, knots and metres per second, which is useful for driving abroad and for reading wind forecasts. The Data Storage Converter covers bits, bytes, megabytes and terabytes, and is worth reaching for whenever a file size and a quota are quoted in different units. When you are not sure which category a unit belongs to, open the general Unit Converter and pick from the list there. All of them calculate in the browser as you type, with no sign-up needed.

7 tools available

Showing 1–7 of 7

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Unit Converter

Convert between length, weight, area, volume, speed, data storage and temperature units in a single tool.

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Unit Converters 488 uses
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Temperature Converter

Convert one temperature into Celsius, Fahrenheit, Kelvin and Rankine at once, with the formulas shown.

Unit Converters 371 uses
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Length Converter

Convert lengths across nine metric and imperial units, with the formula shown and all units listed together.

Unit Converters 298 uses
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Weight Converter

Convert weight between milligrams, grams, kilograms, tonnes, ounces, pounds, stones and US short tons.

Unit Converters 203 uses
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Volume Converter

Convert volumes between metric and US units, from cubic metres to teaspoons, with the conversion factor shown.

Unit Converters 300 uses
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Speed Converter

Convert speeds between km/h, mph, m/s, ft/s, knots, cm/s, km/s, mi/s, Mach and the speed of light.

Unit Converters 308 uses
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Data Storage Converter

Convert data sizes between bits, bytes and every SI and IEC unit from kilobytes to petabytes.

Unit Converters 432 uses

Other Categories

🔢 Basic Everyday Calculators 🔧 media file converter 📐 Scientific & Math Calculators 💰 Finance Calculators 💪 Health & Fitness Calculators 📅 Date & Time Calculators 🏗️ Construction & Engineering 📊 Business Calculators

Why one value converts to two different answers

Internally every entry is reduced to bits, which act as a common base, and then expanded into the target unit. A byte is defined as 8 bits. From there the two families diverge. SI decimal units follow powers of ten, so a kilobyte is 10 to the power of 3 bytes, a megabyte 10 to the power of 6, a gigabyte 10 to the power of 9, a terabyte 10 to the power of 12 and a petabyte 10 to the power of 15. IEC binary units follow powers of two, so a kibibyte is 2 to the power of 10 bytes, which is 1,024, a mebibyte 2 to the power of 20, a gibibyte 2 to the power of 30, a tebibyte 2 to the power of 40 and a pebibyte 2 to the power of 50.

The conversion is therefore value multiplied by the source unit's bit weight, divided by the target unit's bit weight. The tool displays that ratio explicitly, for example 1 GB equals 0.931323 GiB, so you can see exactly which definition produced the number rather than guessing which convention a piece of software used.

Worked example: a 500 GB drive in Windows

Enter 500, set the source unit to GB and the target to GiB. In SI terms, 500 GB is 500 x 10 to the power of 9 bytes, which is 500,000,000,000 bytes. A gibibyte is 1,073,741,824 bytes. Dividing gives 465.661 GiB.

That single calculation explains a complaint as old as hard drives. The manufacturer sells the drive as 500 GB because it genuinely holds 500 billion bytes. Windows reports free space using binary units but labels them GB, so the same drive appears as roughly 466 GB in File Explorer. Nothing is missing; the two numbers are measuring in different bases. macOS and most Linux file managers use decimal units, which is why the same drive reads closer to 500 there.

The gap widens as capacity grows because the ratio compounds. A 1 TB drive is 0.9095 TiB, showing as about 931 GB, and a 4 TB drive loses roughly 363 GB of apparent capacity to the same arithmetic.

Choosing the right unit for the job

Use decimal SI units for storage capacity quoted by manufacturers, for cloud storage tiers and for most data transfer allowances, since these industries advertise in powers of ten. Use binary IEC units when working with memory, file sizes reported by operating systems, block sizes and anything measured by the system itself, because those are addressed in powers of two.

The bigger trap is bits versus bytes. Network and broadband speeds are quoted in bits per second, while file sizes are in bytes, and the difference is a factor of eight. A 100 Mbps connection transfers at most about 12.5 MB per second before protocol overhead, so a 1 GB download takes around 80 seconds at best, not ten.

Watch the capitalisation as well: a capital B means bytes and a lowercase b means bits, so MB and Mb differ eightfold. Where precision matters, quote the byte count in full rather than relying on a unit label that different tools interpret differently.

Frequently Asked Questions

Strictly, 1 GB equals 1,000 MB under the SI decimal definition used by storage manufacturers and standards bodies. The 1,024 figure belongs to the gibibyte, written GiB. Many operating systems still label binary quantities as GB, which is why both numbers circulate for the same unit.
The drive holds 1 trillion bytes, which is genuinely 1 TB in decimal units. Windows divides by 1,024 three times to reach 931.32, then labels the result GB rather than GiB. No capacity is lost; the operating system is simply reporting tebibytes and gibibytes under decimal names.
A capital B means bytes and a lowercase b means bits, and there are 8 bits in a byte. So 1 MB is 8 Mb. Internet speeds are advertised in megabits per second while downloads are measured in megabytes, which is why a 100 Mbps line delivers about 12.5 MB per second.
They are the IEC binary units introduced to remove ambiguity from kilobyte, megabyte and gigabyte. A kibibyte is 1,024 bytes, a mebibyte 1,048,576 bytes and a gibibyte 1,073,741,824 bytes. Their symbols are KiB, MiB and GiB. Memory modules and operating system reports are naturally expressed in these units.
It depends entirely on encoding, so treat any figure as approximate. A 1 GB allowance holds roughly 250 smartphone photos at 4 MB each, about 200 songs at 5 MB, or around ten minutes of 4K video. Convert your actual average file size with the tool for a figure that matches your own files.