Convert Units with Reliable,
High-Precision Calculations
Convert between Metric, US Customary, and Imperial measurement units using carefully sourced conversion factors and high-precision decimal arithmetic.
inch = yard × 36Popular Converters
Frequently accessed unit conversions with complete formulas, calculation steps, and lookup tables.
Yards to Inches
yd → inYards to Feet
yd → ftYards to Meters
yd → mYards to Centimeters
yd → cmFeet to Inches
ft → inFeet to Yards
ft → ydInches to Feet
in → ftInches to Yards
in → ydMeters to Feet
m → ftFeet to Meters
ft → mMiles to Kilometers
mi → kmKilometers to Miles
km → miCentimeters to Inches
cm → inInches to Centimeters
in → cmMiles to Feet
mi → ftFeet to Miles
ft → miMillimeters to Inches
mm → inInches to Millimeters
in → mmPounds to Kilograms
lb → kgKilograms to Pounds
kg → lbOunces to Grams
oz → gGrams to Ounces
g → ozPounds to Ounces
lb → ozOunces to Pounds
oz → lbCelsius to Fahrenheit
°C → °FFahrenheit to Celsius
°F → °CCelsius to Kelvin
°C → KKelvin to Celsius
K → °CMiles per Hour to Kilometers per Hour
mph → km/hKilometers per Hour to Miles per Hour
km/h → mphMeters per Second to Kilometers per Hour
m/s → km/hKnots to Miles per Hour
kn → mphSquare Feet to Square Meters
ft² → m²Square Meters to Square Feet
m² → ft²Acres to Hectares
ac → haHectares to Acres
ha → acSquare Miles to Square Kilometers
mi² → km²Liters to US Gallons
L → galUS Gallons to Liters
gal → LMilliliters to US Fluid Ounces
mL → fl ozUS Fluid Ounces to Milliliters
fl oz → mLUS Cups to Milliliters
cup → mLUS Fluid Ounces to US Cups
fl oz → cupUS Cups to US Fluid Ounces
cup → fl ozHours to Minutes
h → minMinutes to Seconds
min → sDays to Hours
d → hSeconds to Milliseconds
s → msWeeks to Days
wk → dConversion Categories
Explore dedicated conversion hubs across all supported physical dimensions.
Length
Convert distance and length measurements between Metric, US Customary, and Imperial systems.
Weight & Mass
Convert mass and weight between Metric kilograms/grams and US Customary pounds/ounces.
Area
Convert square units, land parcels, acres, hectares, and surface area dimensions.
Volume & Capacity
Convert liquid and dry volume between Liters, US Gallons, Imperial Gallons, and fluid ounces.
Temperature
Convert thermodynamic temperature scales between Celsius, Fahrenheit, and Kelvin.
Speed & Velocity
Convert velocity across Miles per Hour, Kilometers per Hour, Knots, and Meters per Second.
Time
Convert durations between seconds, minutes, hours, days, weeks, and milliseconds.
How Unit Conversion Works
Most unit conversions are linear: a quantity is converted to an intermediate base unit (such as the meter for length or the kilogram for mass) and then converted into the target unit using an exact ratio.
Non-linear conversions (such as temperature scales) include an addition or subtraction offset because their zero points do not align.
Common Measurement Systems
Three primary systems are encountered in commerce and science:
- Metric / SI: Base-10 system used internationally in science, technology, and governance.
- US Customary: Based on historical English units with specific legal definitions (e.g., 1 US gallon = 231 cu in).
- British Imperial: Standardized in 1824 and revised in 1985 (e.g., 1 Imperial gallon = 4.54609 L).
Why Accurate Conversions Matter
Unit mismatches cause real-world failures. In 1999, the $125M Mars Climate Orbiter was lost because thruster data was transmitted in pound-seconds instead of newton-seconds. In aviation and medicine, precise definitions and unambiguous regional variants prevent critical miscalculations.
Unit-Scale eliminates ambiguity by explicitly separating similarly named units such as US fluid ounces and Imperial fluid ounces.
Methodology, Sources & Verification
We document our calculation algorithms, reference citations, and data validation rules so you can verify exactly how conversions are performed.
How conversion factors are stored, calculated, and rounded in code.
References including NIST SP 811, BIPM SI definitions, and ISO standards.
Our design principles: speed, mathematical clarity, and zero ad clutter.
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