Conversion index
Unit converters.
A precise little shelf of everyday conversions. Each pair is explicit, tested, and calculated entirely in your browser.
ready now
Length
Metric and imperial distance, height, and dimension conversions.
CM to Inches
Convert centimeters to inches instantly with the exact 2.54 cm-per-inch relationship.
Inches to CM
Convert inches to centimeters instantly using the exact 2.54 centimeters-per-inch definition.
Miles to KM
Convert statute miles to kilometers with a tested exact conversion factor.
KM to Miles
Convert kilometers to statute miles with a precise, browser-only calculation.
Feet to Meters
Convert feet to meters using the exact 0.3048 meters-per-foot definition.
Meters to Feet
Convert meters to feet using the exact international foot relationship.
Area
Room, land, and map-area conversions with explicitly squared units.
Square Feet to Square Meters
Convert square feet to square meters using the exact international foot relationship.
Square Meters to Square Feet
Convert square meters to square feet with a precise area conversion factor.
Acres to Hectares
Convert acres to hectares for land and property measurements.
Hectares to Acres
Convert hectares to acres with an accurate land-area factor.
Square Miles to Square Kilometers
Convert square miles to square kilometers using the exact statute-mile relationship.
Square Kilometers to Square Miles
Convert square kilometers to square miles with a precise area factor.
Square Inches to Square Centimeters
Convert square inches to square centimeters using the exact inch definition.
Square Centimeters to Square Inches
Convert square centimeters to square inches with an exact area factor.
Mass
Metric mass, avoirdupois weight, and British stone conversions.
KG to LBS
Convert kilograms to avoirdupois pounds with a precise tested factor.
LBS to KG
Convert avoirdupois pounds to kilograms using the exact pound definition.
Grams to Ounces
Convert grams to avoirdupois ounces using the international ounce definition.
Ounces to Grams
Convert avoirdupois ounces to grams with a precise international factor.
Stone to Kilograms
Convert British stones to kilograms using the exact 14-pound stone definition.
Kilograms to Stone
Convert kilograms to British stones with a precise weight factor.
Volume
US kitchen and liquid-volume relationships with clearly named units.
Cups to ML
Convert US customary cups to milliliters for cooking and volume measurements.
ML to Cups
Convert milliliters to US customary cups with clear common-volume references.
Gallons to Liters
Convert US liquid gallons to liters using the exact US gallon definition.
Liters to Gallons
Convert liters to US liquid gallons with a precise browser-only calculation.
fl oz to mL
Convert US customary fluid ounces to milliliters for liquid volume measurements.
mL to fl oz
Convert milliliters to US customary fluid ounces with a precise factor.
Cubic Feet to Cubic Meters
Convert cubic feet to cubic meters using the exact international foot relationship.
Cubic Meters to Cubic Feet
Convert cubic meters to cubic feet with a precise volume factor.
Energy & power
Common electrical, thermal, and mechanical energy and power relationships.
kWh to MJ
Convert electrical energy from kilowatt-hours to megajoules.
MJ to kWh
Convert megajoules to kilowatt-hours with the exact 3.6 MJ-per-kWh relationship.
BTU to kJ
Convert International Table British thermal units to kilojoules.
kJ to BTU
Convert kilojoules to International Table British thermal units with a precise factor.
J to calₜₕ
Convert joules to thermochemical calories using 1 cal_th = 4.184 J.
calₜₕ to J
Convert thermochemical calories to joules with the reciprocal of the stated constant.
HP to kW
Convert mechanical horsepower to kilowatts using the standard 550-foot-pound-per-second definition.
kW to HP
Convert kilowatts to mechanical horsepower with a precise power factor.
Angle
Translate degrees and radians with the exact π relationship.
Force & torque
Compare newtons, pound-force, kilogram-force, and common torque units.
N to lbf
Convert newtons to pound-force using 1 lbf = 4.4482216152605 N.
lbf to N
Convert pound-force to newtons with the reciprocal of the stated constant.
kgf to N
Convert kilogram-force to newtons using the standard gravitational-force constant 1 kgf = 9.80665 N.
N to kgf
Convert newtons to kilogram-force with the reciprocal of the stated constant.
kN to lbf
Convert kilonewtons to pound-force using 1 kN = 1000 N and 1 lbf = 4.4482216152605 N.
lbf to kN
Convert pound-force to kilonewtons with the reciprocal of the stated constant.
N·m to lb·ft
Convert torque from newton-meters to pound-feet using 1 N·m = 0.737562149277 lb·ft.
lb·ft to N·m
Convert pound-feet to newton-meters with the reciprocal of the stated constant.
N·m to lb·in
Convert torque from newton-meters to pound-inches using 1 N·m = 8.850745791327 lb·in.
lb·in to N·m
Convert pound-inches to newton-meters with the reciprocal of the stated constant.
Frequency
Move between decimal frequency units and one-cycle-per-revolution rotational speed.
Hz to kHz
Convert frequency from hertz to kilohertz using decimal kilo (1000 hertz = 1 kilohertz).
kHz to Hz
Convert kilohertz to hertz with the reciprocal of the stated constant.
MHz to GHz
Convert frequency from megahertz to gigahertz using decimal mega/giga prefixes (1000 megahertz = 1 gigahertz).
GHz to MHz
Convert gigahertz to megahertz with the reciprocal of the stated constant.
Hz to rpm
Convert hertz to revolutions per minute when one cycle corresponds to one revolution; 1 Hz = 60 rpm.
rpm to Hz
Convert revolutions per minute to hertz with the reciprocal of the stated constant.
Data & rate
Convert decimal bit and byte quantities or network transfer rates with explicit 8-bit-byte semantics.
b to B
Convert bits to bytes using the exact 8 bits per byte relationship.
B to b
Convert bytes to bits with the reciprocal of the stated constant.
kb to kB
Convert decimal kilobits to decimal kilobytes; the shared decimal kilo factor cancels, leaving 8 kilobits per kilobyte.
kB to kb
Convert kilobytes to kilobits with the reciprocal of the stated constant.
Mb to MB
Convert decimal megabits to decimal megabytes; the shared decimal mega factor cancels, leaving 8 megabits per megabyte.
MB to Mb
Convert megabytes to megabits with the reciprocal of the stated constant.
Gb to GB
Convert decimal gigabits to decimal gigabytes; the shared decimal giga factor cancels, leaving 8 gigabits per gigabyte.
GB to Gb
Convert gigabytes to gigabits with the reciprocal of the stated constant.
Mbps to MB/s
Convert decimal megabits per second to megabytes per second using 8 bits per byte.
MB/s to Mbps
Convert megabytes per second to megabits per second with the reciprocal of the stated constant.
Gbps to MB/s
Convert gigabits per second to decimal megabytes per second; 1 Gbps = 125 MB/s.
MB/s to Gbps
Convert megabytes per second to gigabits per second with the reciprocal of the stated constant.
Temperature
Celsius, Fahrenheit, and kelvin conversions with absolute-zero validation.
Celsius to Fahrenheit
Convert degrees Celsius to degrees Fahrenheit with the standard scale-and-offset formula.
Fahrenheit to Celsius
Convert degrees Fahrenheit to degrees Celsius with the standard offset-and-scale formula.
Celsius to Kelvin
Convert degrees Celsius to kelvins using the exact 273.15 offset.
Kelvin to Celsius
Convert kelvins to degrees Celsius using the exact 273.15 offset.
Fahrenheit to Kelvin
Convert degrees Fahrenheit to kelvins with a tested affine conversion.
Kelvin to Fahrenheit
Convert kelvins to degrees Fahrenheit with a tested affine conversion.
Speed
Road, scientific, and nautical speed units with exact named relationships.
MPH to KM/H
Convert miles per hour to kilometers per hour using the exact mile definition.
KM/H to MPH
Convert kilometers per hour to miles per hour using the exact mile definition.
Knots to KM/H
Convert knots to kilometers per hour using the exact international nautical-mile relationship.
KM/H to Knots
Convert kilometers per hour to knots using the international nautical-mile relationship.
M/S to KM/H
Convert meters per second to kilometers per hour with the exact 3.6 factor.
KM/H to M/S
Convert kilometers per hour to meters per second with the exact 3.6 relationship.
Pressure
PSI and bar for practical pressure comparisons.
Fuel economy
Reciprocal US MPG and liters-per-100-kilometer conversions.
Flow
Liters and US gallons per minute for liquid-flow estimates.
Exact definitions and rounded answers
Many everyday conversions are exact by definition. Since 1959 an inch is exactly 2.54 centimetres and a pound exactly 0.45359237 kilograms, so cm to inches and kg to lbs are fixed ratios rather than measurements. Each converter shows the factor it uses, a table of common values, and the multiplication worked out, so any result can be checked by hand.
A long decimal result is the arithmetic, not a claim about your measurement. Round the answer to the precision of what you measured: a height known to the nearest centimetre does not become more exact in inches.
US and imperial units are not the same
A US gallon is 3.785 litres; an imperial gallon, still used for fuel in the UK, is 4.546. A US fluid ounce is 29.57 millilitres against 28.41 for the imperial one, and a US cup of 236.6 millilitres is smaller than the 250-millilitre metric cup in many recipes. The gallons to liters, fl oz to ml, and cups to ml converters use the US units and say so.
Conversions that are not a single multiplication
Temperature scales have different zero points, so Celsius to Fahrenheit multiplies and then adds 32. A temperature change converts differently from a temperature: a rise of 10 °C is a rise of 18 °F, not 50.
Fuel economy runs in opposite directions: miles per gallon counts distance per fuel, litres per 100 km counts fuel per distance. That is why going from 10 to 20 mpg saves more fuel than going from 30 to 60 — mpg to L/100 km makes it visible.
Bits, bytes, and file sizes
Internet speeds are quoted in bits per second, file sizes in bytes, and a byte is eight bits — so a 100 Mbps connection downloads at most 12.5 megabytes per second (Mbps to MB/s). Storage adds another split: a megabyte is 1,000,000 bytes, while a mebibyte (MiB), which many operating systems label MB, is 1,048,576. The file size converter shows both.