Construction Unit Converters
Exact US customary → metric factors for job-site math, plus typical bulk-material weights for estimating lumber, concrete, gravel, and site area. Length and area factors are exact; bulk weights are ranges to confirm with your supplier.
Direct answer
- • 1 board foot = 144 in³ = 1/12 ft³ (lumber volume).
- • 1 cubic yard = 27 ft³ ≈ 0.7646 m³; typical gravel ≈ 1.4 short tons (range 1.3–1.6).
- • 1 acre = 43,560 ft²; 1 sq ft = 0.09290304 m².
- • 1 ft = 0.3048 m, 1 in = 2.54 cm, 1 yd = 0.9144 m (all exact).
Exact length & area factors (NIST)
| From | To | Factor |
|---|---|---|
| 1 inch | centimetre | 2.54 (exact) |
| 1 foot | metre | 0.3048 (exact) |
| 1 yard | metre | 0.9144 (exact) |
| 1 mile | kilometre | 1.609344 (exact) |
| 1 square foot | square metre | 0.09290304 (exact) |
| 1 square yard | square foot | 9 (exact) |
| 1 acre | square foot | 43,560 (exact) |
Lumber & volume
| Unit | Equals | Use |
|---|---|---|
| 1 board foot (BF) | 144 in³ = 1/12 ft³ | Hardwood lumber pricing |
| 1 cubic foot | 1,728 in³ = 0.0283168 m³ | Concrete / fill volume |
| 1 cubic yard | 27 ft³ = 0.764555 m³ | Aggregate / concrete orders |
Typical bulk-material weights (per cubic yard)
| Material | Typical weight | Note |
|---|---|---|
| Gravel / crushed stone | ≈ 1.3–1.6 short tons | Wet & finer = heavier |
| Sand | ≈ 1.2–1.4 short tons | Moisture dependent |
| Topsoil | ≈ 1.0–1.3 short tons | Varies with compost mix |
| Concrete (standard mix) | ≈ 2.0 short tons (≈ 4,000 lb) | Mix design dependent |
Bulk weights are typical industry ranges, not exact constants. Always confirm the density on your supplier’s batch ticket or product data sheet before ordering or load-planning.
How to estimate
Board feet: (thickness in × width in × length ft) ÷ 12.
Cubic yards of aggregate: (length ft × width ft × depth ft) ÷ 27, then × material weight per yard for tonnage.
Area: sq ft ÷ 10.7639 = sq m; acres × 4,046.86 = sq m.
Frequently Asked Questions
How do you calculate board feet?
A board foot is 144 cubic inches of lumber (a 12″ × 12″ × 1″ board). Formula: board feet = (thickness in inches × width in inches × length in feet) ÷ 12. Example: a 2″ × 6″ × 8 ft board = (2 × 6 × 8) ÷ 12 = 8 board feet.
How many tons is a cubic yard of gravel?
A cubic yard of typical gravel weighs about 1.4 short tons (≈2,800 lb), but the range is roughly 1.3–1.6 tons depending on moisture and stone size. Crushed stone and wet sand are heavier; always confirm the density with your supplier or batch ticket before ordering.
Are the length and area factors exact?
Yes. By international definition: 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 yard = 0.9144 m, 1 acre = 43,560 ft², and 1 square foot = 0.09290304 m² (NIST SP 330 / SP 811). These have no rounding error beyond the decimals you display.
Can I print this reference for the job site?
Yes. Use the “Print / Save as PDF” button — it prints the factors and tables cleanly on A4, with navigation and ads removed.
Related Converters
Sources & Accuracy
Length, area, and volume factors are exact international definitions:
- • 1 in = 2.54 cm, 1 ft = 0.3048 m, 1 yd = 0.9144 m, 1 mile = 1.609344 km
- • 1 ft² = 0.09290304 m², 1 acre = 43,560 ft², 1 yd³ = 0.764555 m³
Bulk-material weights are typical ranges from common US construction references; they are not fixed physical constants and should be verified per load.
Definitions: NIST SP 330 (SI) and NIST SP 811 (US Customary).
Last Updated 2026 | Exact factors verified against NIST SP 330 / SP 811; bulk weights are typical ranges