How dimension conversion works
Every length unit converts to every other through the meter, which is the SI base unit. The exact conversion factors that drive this calculator:
1 in = 0.0254 m (exact, since 1959) 1 ft = 0.3048 m (exact, 12 × 0.0254) 1 yd = 0.9144 m (exact, 36 × 0.0254) 1 mm = 0.001 m 1 cm = 0.01 m area = L × W (then convert each axis squared) volume = L × W × H (then convert each axis cubed) 1 L = 0.001 m³ 1 US gal = 3.785411784 L (exact, since 1893) 1 cu yd = 27 cu ft (the buy unit for bulk concrete and aggregate)
Common construction conversions to memorize
- 27 cu ft = 1 cu yd — the bulk-material buy unit for concrete, gravel, mulch and topsoil.
- 2.54 cm = 1 in — exactly. The whole imperial-to-metric system pivots on this number.
- 9 sq ft = 1 sq yd — relevant for fabric, carpet and small lawn-care orders.
- 3.785 L = 1 US gallon — paint, stain, sealer, primer all priced per US gallon in North America.
- 1 cu ft ≈ 7.48 US gallons — useful for sizing rain barrels, pond volumes and concrete forms.
Common mistakes
- Confusing US and Imperial gallons. Imperial gallons are about 20% larger than US gallons. This calculator outputs US gallons, the North American default.
- Forgetting to cube the conversion factor for volume. 1 m = 3.281 ft, but 1 m³ = 35.314 ft³ (not 3.281). Always cube the linear factor for volumes.
- Mixing dimensions and units. If your length is in feet, your width must also be in feet — this calculator forces a single input unit so you cannot accidentally mix them.
- Reading "yards" as "feet" on a delivery slip. 5 cubic yards of gravel is 5 × 27 = 135 cubic feet — quite different from 5 cubic feet.
