Unit Converter

Convert units of length, weight, temperature, area, volume, speed, digital storage, and time. Real-time conversion with all units shown.

What is Unit Converter?

A Unit Converter is a comprehensive calculation tool that transforms measurements between the many different unit systems used across science, engineering, cooking, travel, fitness, and everyday life. The world uses two primary measurement systems that are not compatible: the metric system (SI—Système International), used by most of the world and universal in science, and the imperial system (US customary units), used in the United States for most everyday measurements. This creates constant conversion needs: a recipe from a US cookbook gives ounces but your kitchen scale uses grams; a product specification lists dimensions in inches but your engineering drawing uses millimeters; an international flight lists weight allowances in kilograms but you know your luggage weight in pounds; a server's disk space shows in gibibytes but you need to compare it with marketing's 'gigabytes'. Beyond metric-imperial conversions, digital storage units are notoriously confusing—the difference between a kilobyte (1,000 bytes in SI) and a kibibyte (1,024 bytes in binary), and why your 1TB hard drive only shows 931GB in Windows. This tool handles all measurement categories with high precision and shows all units simultaneously for easy comparison.

How to Use Unit Converter

Select a measurement category from the tabs at the top: Length, Weight/Mass, Temperature, Area, Volume, Speed, Digital Storage, or Time. Enter a numeric value into any unit's input field—all other units in that category update instantly in real-time as you type, showing the equivalent value in every available unit simultaneously. You do not need to select 'from' and 'to' units separately—all conversions happen at once. For example, typing '100' in the Celsius field immediately shows 212 Fahrenheit and 373.15 Kelvin. Scroll through all the units displayed to find the one you need. The precision is set to the appropriate number of decimal places for each unit type. For digital storage, the tool clearly distinguishes between SI prefixes (KB = 1,000 bytes, MB = 1,000,000 bytes) and binary prefixes (KiB = 1,024 bytes, MiB = 1,048,576 bytes) to avoid the common confusion between the two systems.

FAQ

What measurement categories are available?

Eight categories are covered: Length (millimeter, centimeter, meter, kilometer, inch, foot, yard, mile, nautical mile, light-year), Weight/Mass (milligram, gram, kilogram, metric ton, ounce, pound, stone, US ton), Temperature (Celsius, Fahrenheit, Kelvin), Area (square meter, square kilometer, square foot, square mile, acre, hectare), Volume (milliliter, liter, cubic meter, fluid ounce, cup, pint, quart, gallon), Speed (m/s, km/h, mph, knots, ft/s), Digital Storage (bit, byte, KB, MB, GB, TB, KiB, MiB, GiB, TiB), and Time (millisecond, second, minute, hour, day, week, month, year).

How accurate are the conversions?

All conversions use precise standard conversion factors defined by international standards bodies (BIPM, NIST). Calculations are performed using JavaScript floating-point arithmetic with up to 10–15 significant digits of precision—more than sufficient for engineering, science, cooking, and everyday use. Temperature conversions use the exact offset formulas (not rounded approximations), so °C to °F is (°C × 9/5) + 32 and Kelvin is °C + 273.15.

What is the difference between kilobyte (KB) and kibibyte (KiB)?

This is one of the most confusing distinctions in computing. KB (kilobyte) in SI units = 1,000 bytes exactly, as used by storage manufacturers, network speed ratings, and many Linux tools. KiB (kibibyte) in binary = 1,024 bytes, as used by operating systems, RAM ratings, and file systems. So a 1TB drive (1,000,000,000,000 bytes as advertised) is 0.909 TiB as shown by Windows and macOS (which calculate in binary). The IEC 80000-13 standard introduced KiB/MiB/GiB to eliminate this ambiguity.

Why does Kelvin not use the degree symbol (°)?

Kelvin is the SI base unit for thermodynamic temperature and is defined as an absolute scale starting from absolute zero (the coldest possible temperature, −273.15°C). Because Kelvin measures absolute thermodynamic temperature—not relative temperature differences—it does not use the degree symbol. You say '300 kelvin' (abbreviated as 300 K), not '300 degrees kelvin'. All other temperature scales (Celsius, Fahrenheit, Rankine) use the degree symbol because they are relative scales with arbitrary zero points.

How do I convert cooking measurements from US cups to metric?

Use the Volume category. US measurements: 1 cup = 236.6 mL, 1 tablespoon = 14.79 mL, 1 teaspoon = 4.93 mL, 1 fluid ounce = 29.57 mL, 1 pint = 473.2 mL, 1 quart = 946.4 mL, 1 gallon = 3,785 mL. Note that these are liquid volume measurements—for dry ingredient conversions (cups of flour to grams), you also need the ingredient's density, as 1 cup of flour weighs very differently than 1 cup of sugar or 1 cup of butter.