Metric–Imperial Pocket Card — Exact Conversion Factors
One-page conversion card: exact NIST length, area, volume, and pressure factors plus temperature scale relations and absolute zero.
Updated August 20, 2026
The conversion factors worth pinning above the bench, on one printable card: the international yard-and-pound length definitions, area and volume factors from NIST SP 811 Appendix B, the pascal values of the common pressure units, and the four temperature scales with absolute zero in each. Factors marked exact are definitions; the rest are NIST’s published 7-significant-figure values. °F = 1.8 × °C + 32, K = °C + 273.15, °R = °F + 459.67.
Every cell is the exported constant behind the engineering unit, pressure, and temperature converters, printed without rounding — never retyped. Inch-fraction decimals stay on the decimal equivalents card; the linked converters handle the multiplication and the edge cases.
Metric–Imperial Pocket Card — Exact Conversion Factors — updated August 20, 2026
Length (NIST SP 811, exact)
| Unit | Metres |
|---|---|
| m | 1 |
| mm | 0.001 |
| cm | 0.01 |
| km | 1000 |
| in | 0.0254 |
| ft | 0.3048 |
| yd | 0.9144 |
| mi | 1609.344 |
The in/ft/yd/mi factors are the international 1959 definitions — exact by definition. Inch fractions ↔ mm live on the decimal equivalents card.
Area
| Unit | Square metres |
|---|---|
| m² | 1 |
| mm² | 0.000001 |
| cm² | 0.0001 |
| in² | 0.00064516 |
| ft² | 0.09290304 |
| acre | 4046.873 |
| hectare | 10000 |
in² and ft² exact; the acre is NIST’s 7-figure US survey value.
Volume
| Unit | Cubic metres |
|---|---|
| m³ | 1 |
| L | 0.001 |
| in³ | 0.000016387064 |
| ft³ | 0.02831685 |
| US gal | 0.003785412 |
| yd³ | 0.7645549 |
in³ and L exact; ft³, US gal, and yd³ are NIST 7-figure values.
Pressure
| Unit | Pascals |
|---|---|
| Pa | 1 |
| kPa | 1000 |
| MPa | 1000000 |
| bar | 100000 |
| psi | 6894.757 |
| ksi | 6894757 |
| atm | 101325 |
| Torr (mmHg) | 133.3224 |
| inH₂O (39.2 °F) | 249.082 |
| kgf/cm² | 98066.5 |
bar, atm, and kgf/cm² exact; psi/ksi, Torr, and inH₂O are NIST 7-figure values.
Temperature scales & absolute zero
| Scale | Absolute zero |
|---|---|
| °C (Celsius) | -273.15 |
| °F (Fahrenheit) | -459.67 |
| K (Kelvin) | 0 |
| °R (Rankine) | 0 |
Exact by definition: −273.15 °C = 0 K; °R = °F + 459.67. Scale relations in the intro above.
Sources
- NIST SP 811, Appendix B conversion factors
- International yard-and-pound agreement (1959) exact definitions
- SI Brochure: kelvin/Celsius definition (−273.15 °C = 0 K)
Try the Calculators
Metric–Imperial Pocket Card — Exact Conversion Factors — reuven.tools/cheat-sheets/metric-imperial-pocket-card — verified against: NIST SP 811, Appendix B conversion factors; International yard-and-pound agreement (1959) exact definitions; SI Brochure: kelvin/Celsius definition (−273.15 °C = 0 K)