Construction Unit Converter
Length, area, volume, weight, temperature and pressure plus trade extras — cubic yards, board feet, gallons, PSI and wire gauge — with exact factors and your own rounding.
Convert
Conversions use exact factors at full precision — this only controls the displayed rounding.
1 ft =
0.3048 m
Construction unit conversions, done exactly
Every conversion uses the exact SI ratio for the unit — never a chained approximation. One inch is exactly 0.0254 m, one US gallon is exactly 3.785411784 L, and one cubic yard is exactly 27 cubic feet. Full precision is preserved internally; the rounding control only changes what you see.
Exact conversion factors
| From | To | Exact factor |
|---|---|---|
| 1 inch | metres | 0.0254 |
| 1 foot | metres | 0.3048 |
| 1 yard | metres | 0.9144 |
| 1 pound | kilograms | 0.45359237 |
| 1 US gallon | litres | 3.785411784 |
| 1 cubic yard | cubic feet | 27 |
| 1 PSI | kPa | 6.894757 |
Cubic yards ↔ cubic feet
| Cubic yards | Cubic feet |
|---|---|
| 0.5 | 13.5 |
| 1 | 27 |
| 2 | 54 |
| 5 | 135 |
| 10 | 270 |
Board feet quick reference
| Lumber | Length | Board feet |
|---|---|---|
| 2 × 4 | 8 ft | 5.33 |
| 2 × 6 | 8 ft | 8.00 |
| 2 × 8 | 10 ft | 13.33 |
| 2 × 10 | 12 ft | 20.00 |
| 4 × 4 | 8 ft | 10.67 |
Wire gauge (AWG) ↔ millimetres
| AWG | Diameter (mm) |
|---|---|
| 0000 (4/0) | 11.684 |
| 0 (1/0) | 8.251 |
| 4 | 5.189 |
| 8 | 3.264 |
| 10 | 2.588 |
| 12 | 2.053 |
| 14 | 1.628 |
PSI ↔ kPa
| PSI | kPa |
|---|---|
| 1 | 6.89 |
| 40 | 275.79 |
| 60 | 413.69 |
| 100 | 689.48 |
| 150 | 1,034.21 |
Watch out for
- •Wire gauge vs sheet gauge. AWG (above) is for wire. Steel, aluminum and galvanized sheet use different gauge tables for the same number.
- •US vs Imperial gallons. A US gallon is 3.785 L; an Imperial gallon is 4.546 L. Pick the right one.
- •Board feet use nominal lumber dimensions (a “2 × 4”), not the actual dressed size.
Frequently asked questions
How many cubic feet are in a cubic yard?+
There are exactly 27 cubic feet in one cubic yard. To convert cubic yards to cubic feet, multiply by 27; to go the other way, divide by 27.
How do I convert PSI to kPa?+
Multiply PSI by 6.894757 to get kilopascals. For example, 100 PSI = 689.48 kPa. To convert kPa back to PSI, divide by 6.894757.
How do I calculate board feet?+
Board feet = thickness (inches) × width (inches) × length (feet) ÷ 12. A 2 × 6 board 8 feet long is 2 × 6 × 8 ÷ 12 = 8 board feet. Use the nominal lumber size.
What is AWG 12 in millimetres?+
AWG 12 wire is 2.053 mm in diameter. American Wire Gauge is defined by d(mm) = 0.127 × 92^((36 − n) ÷ 39). Note that sheet-metal gauge uses a different table.
Methodology & sources
Standard conversions use the exact SI ratios published by NIST (1 in = 0.0254 m, 1 lb = 0.45359237 kg, 1 US gal = 3.785411784 L). Each conversion is a single value × (from→base) ÷ (to→base) operation — conversions are never chained.
Board feet uses the lumber convention (thickness × width in inches × length in feet ÷ 12). Wire gauge uses the exact American Wire Gauge definition; sheet-metal gauge varies by material and is not the same table.
- NIST Special Publication 811 (2008) — SI unit conversion factors — verified June 28, 2026
- ASTM B258 — Standard Nominal Diameters (American Wire Gauge) — verified June 28, 2026
Last reviewed June 28, 2026. Estimates are indicative — verify against current product specs and local requirements before ordering.
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