Units Converter
Converts a numeric value between compatible engineering units across 18 categories. The category taxonomy mirrors unitconverters.net; conversion factors are SI/NIST-exact (International Table calorie/BTU convention).
Pick a Category first — the From and To lists then show only the units in that category.
Supported categories
| Category | Units |
|---|---|
| Length | m, km, dm, cm, mm, µm, mi, yd, ft, in |
| Area | m², km², cm², mm², ha, mi², yd², ft², in², acre |
| Volume | m³, L, mL, cm³, ft³, in³, gal (US), gal (UK), qt (US), pt (US), fl oz (US), bbl |
| Temperature | K, °C, °F, °R |
| Mass / Weight | kg, g, mg, t, lb, oz, slug, gr |
| Pressure | Pa, kPa, MPa, bar, mbar, atm, psi, torr, mmHg, inHg, mmH₂O |
| Energy | J, kJ, MJ, Wh, kWh, cal, kcal, BTU (IT), ft·lbf, therm (US), eV |
| Power | W, kW, MW, hp, hp, BTU/h, ft·lbf/s, cal/s (IT) |
| Force | N, kN, dyn, kgf, lbf, ozf, pdl |
| Speed | m/s, km/h, ft/s, mph, knot, ft/min |
| Volumetric flow | m³/s, m³/h, L/s, L/min, ft³/s, ft³/min, gal/min (US gpm) |
| Density | kg/m³, g/cm³, kg/L, lb/ft³, lb/in³, slug/ft³ |
| Thermal conductivity | W/(m·K), W/(cm·K), kcal/(h·m·°C), cal/(s·cm·°C), BTU/(h·ft·°F), BTU·in/(h·ft²·°F) |
| Heat flux density | W/m², kW/m², W/cm², cal/(s·cm²), kcal/(h·m²), BTU/(h·ft²) |
| Heat-transfer coefficient | W/(m²·K), W/(cm²·K), kcal/(h·m²·°C), cal/(s·cm²·°C), BTU/(h·ft²·°F) |
| Specific heat capacity | J/(kg·K), kJ/(kg·K), cal/(g·°C) (IT), kcal/(kg·°C) (IT), BTU/(lb·°F) (IT) |
| Dynamic viscosity | Pa·s, mPa·s, P, cP, lbf·s/ft², lb/(ft·s) |
| Kinematic viscosity | m²/s, cm²/s, St, cSt, ft²/s, m²/h |
Affine factor-map conversion
Every unit maps to its category's base unit by an affine relation:
base=x⋅f+o,y=fto(x⋅ffrom+ofrom)−otoThe offset o is zero for all categories except temperature, so for ratio units this reduces to y=x⋅ffrom/fto.
Example: 1ft=0.3048m.
Temperature
T∘C=1.8T∘F−32,TK=T∘C+273.15Rankine (°R) is the absolute Fahrenheit scale: T∘R=1.8TK.
Heat-transfer units
The thermal families use the International Table calorie (cal = 4.1868 J, kcal = 4186.8 J, BTU = 1055.05585 J), giving the standard published figures — e.g. 1kcal/(h⋅m⋅°C)=1.163W/(m⋅K) and 1BTU/(lb⋅°F)=4186.8J/(kg⋅K).
Usage note
Selecting From/To units from different categories produces a dimension-mismatch error.