Asphalt Tonnage Formula — Constants, Conversions and Examples
Every formula, constant and conversion needed to calculate asphalt quantities, on one page. Imperial and metric, sixteen mix densities, eleven area formulas, all the unit conversions and six worked examples covering driveways, parking lots, circular areas, multi-lift structures, millings and roads.
The core formulas
Volume (ft³) = Area (sq ft) × Thickness (in) ÷ 12
Weight (lb) = Volume (ft³) × Density (lb/ft³)
Tons = Weight (lb) ÷ 2,000
Combined: Tons = Area × Thickness ÷ 12 × Density ÷ 2,000
Volume (m³) = Area (m²) × Thickness (m)
Weight (kg) = Volume (m³) × Density (kg/m³)
Tonnes = Weight (kg) ÷ 1,000
Combined: Tonnes = Area × Thickness × Density ÷ 1,000
Order = Calculated tonnage × (1 + waste buffer)
Buffer: 0.05 simple · 0.10 standard · 0.15 complex · 0.20 millings
Constants by unit system
For dense-graded hot mix asphalt at 145 lb/ft³ / 2,322.7 kg/m³:
| Working in | Multiply by | Gives | Verify: 1,000 sq ft at 2 in |
|---|---|---|---|
| sq ft × in | 0.006042 | US short tons | 12.08 tons |
| sq ft × ft | 0.0725 | US short tons | 12.08 tons |
| sq yd × in | 0.054375 | US short tons | 12.08 tons |
| sq yd × ft | 0.6525 | US short tons | 12.08 tons |
| m² × cm | 0.023227 | tonnes | 10.96 tonnes |
| m² × mm | 0.0023227 | tonnes | 10.96 tonnes |
| m² × m | 2.3227 | tonnes | 10.96 tonnes |
| ft³ | 0.0725 | US short tons | 12.08 tons |
| cu yd | 1.9575 | US short tons | 12.08 tons |
| m³ | 2.3227 | tonnes | 10.96 tonnes |
A caution on shortcut constants. The figure 0.0031 appears widely online presented as a universal asphalt constant. It matches none of the standard unit combinations above. Applied to square feet and inches it under-orders by about 49%. Always verify a shortcut against the long-form calculation on a known example — 1,000 sq ft at 2 inches should give 12.08 tons — before using it on a purchase order.
Density values to substitute
| Mix type | lb/ft³ | kg/m³ | t/m³ | Air voids | Typical use | Standard |
|---|---|---|---|---|---|---|
| Dense-graded HMA | 145 | 2,322.7 | 2.32 | 3–5% | Standard surface and binder courses for driveways, lots and roads | AASHTO M 323 / Superpave |
| Stone Matrix Asphalt (SMA) | 150 | 2,402.8 | 2.40 | 3–4% | High-traffic highways, rut-resistant surface course | AASHTO M 325 / EN 13108-5 |
| Warm Mix Asphalt (WMA) | 143 | 2,290.7 | 2.29 | 4–6% | Same uses as HMA, produced 30–100 °F cooler | AASHTO M 323 (WMA appendix) |
| Open-Graded Friction Course | 115 | 1,841.8 | 1.84 | 15–22% | Thin porous wearing course for spray and noise reduction | AASHTO M 323 / NAPA IS-115 |
| Porous / Permeable Asphalt | 100 | 1,601.8 | 1.60 | 18–25% | Full-depth permeable pavement, stormwater infiltration lots | NAPA IS-131 |
| Cold Mix Asphalt | 140 | 2,242.6 | 2.24 | 6–10% | Pothole patching, temporary repairs, low-traffic rural surfacing | ASTM D4215 |
| RAP Millings (recycled) | 125 | 2,002.3 | 2.00 | 8–14% | Driveways, base layers, rural roads, temporary access | AASHTO M 323 §RAP |
| Dense Bituminous Macadam (DBM) | 148 | 2,370.8 | 2.37 | 3–6% | Binder / base course in India and South Asia | MoRTH Clause 507 |
| Bituminous Concrete (BC) | 147 | 2,354.7 | 2.35 | 3–5% | Surface course in India (MoRTH), equivalent to dense HMA | MoRTH Clause 509 |
| Bituminous Macadam (BM) | 135 | 2,162.5 | 2.16 | 5–10% | Open-graded base / profile-correcting course, India | MoRTH Clause 504 |
| BBSG 0/10 (Béton Bitumineux Semi-Grenu) | 148 | 2,370.8 | 2.37 | 5–8% | Couche de roulement standard en France, 5–7 cm | NF EN 13108-1 / NF P 98-130 |
| BBME (Béton Bitumineux à Module Élevé) | 150 | 2,402.8 | 2.40 | 4–6% | Couche de roulement à fort trafic, liant modifié | NF EN 13108-1 / NF P 98-141 |
| Grave Bitume (GB3/GB4) | 149 | 2,386.8 | 2.39 | 4–7% | Couche d'assise / de base, France | NF EN 13108-1 / NF P 98-138 |
| EME 2 (Enrobé à Module Élevé) | 152 | 2,434.8 | 2.43 | 2–5% | Couche de base à très fort trafic, épaisseur réduite | NF EN 13108-1 / NF P 98-140 |
| Hot Rolled Asphalt (HRA) | 143 | 2,290.7 | 2.29 | 3–6% | Traditional UK surface course with pre-coated chippings | BS EN 13108-4 / BS 594987 |
| Bitumen binder (PG 64-22 / 60-70 pen) | 65 | 1,041.2 | 1.04 | — | Liquid binder only — tack coat, prime coat, seal coat | AASHTO M 320 / EN 12591 |
Area formulas
| Shape | Formula | Measure |
|---|---|---|
| Rectangle | L × W | Length, width |
| Square | S² | One side |
| Circle | π × r² (or π × d² ÷ 4) | Diameter |
| Half circle | π × r² ÷ 2 | Diameter |
| Quarter circle | π × r² ÷ 4 | Radius |
| Ring | π × (R² − r²) | Outer and inner diameter |
| Triangle | ½ × b × h | Base, perpendicular height |
| Right triangle | ½ × a × b | Two legs |
| Trapezoid | ½ × (a + b) × h | Both parallel sides, perpendicular distance |
| Parallelogram | b × h | Base, perpendicular height |
| Ellipse | π × a × b | Semi-major and semi-minor axes |
| Irregular | Σ of the pieces | Split into the above |
All conversions on one page
Length
| From | To | × |
|---|---|---|
| inch | foot | 0.08333 |
| inch | cm | 2.54 |
| inch | mm | 25.4 |
| foot | metre | 0.3048 |
| yard | metre | 0.9144 |
| cm | inch | 0.3937 |
| metre | foot | 3.28084 |
Area
| From | To | × |
|---|---|---|
| sq ft | sq yd | 0.11111 |
| sq ft | m² | 0.092903 |
| sq yd | sq ft | 9 |
| sq yd | m² | 0.836127 |
| m² | sq ft | 10.7639 |
| m² | sq yd | 1.19599 |
| acre | sq ft | 43,560 |
| hectare | m² | 10,000 |
Volume
| From | To | × |
|---|---|---|
| ft³ | cu yd | 0.037037 |
| ft³ | m³ | 0.0283168 |
| cu yd | ft³ | 27 |
| cu yd | m³ | 0.764555 |
| m³ | ft³ | 35.3147 |
| m³ | cu yd | 1.30795 |
Weight
| From | To | × |
|---|---|---|
| lb | kg | 0.453592 |
| kg | lb | 2.20462 |
| US short ton | tonne | 0.907185 |
| tonne | US short ton | 1.10231 |
| US short ton | lb | 2,000 |
| tonne | kg | 1,000 |
| long ton | US short ton | 1.12 |
Density
| From | To | × |
|---|---|---|
| lb/ft³ | kg/m³ | 16.0185 |
| kg/m³ | lb/ft³ | 0.0624280 |
| lb/ft³ | lb/yd³ | 27 |
| kg/m³ | t/m³ | 0.001 |
| lb/yd³ | kg/m³ | 0.593276 |
Coverage
| Question | Formula |
|---|---|
| sq ft per ton | 2,000 ÷ (density × thickness in ÷ 12) |
| m² per tonne | 1,000 ÷ (density kg/m³ × thickness m) |
| tons per 1,000 sq ft | 1,000 × thickness in ÷ 12 × density ÷ 2,000 |
| ft³ per ton | 2,000 ÷ density |
| m³ per tonne | 1,000 ÷ density kg/m³ |
Worked examples
Example 1 — rectangular driveway, imperial
40 ft × 12 ft at 2.5 inches, dense-graded HMA, 10% buffer.
Volume = 480 × 2.5 ÷ 12 = 100 ft³
Weight = 100 × 145 = 14,500 lb
Tons = 14,500 ÷ 2,000 = 7.25 tons
Order = 7.25 × 1.10 = 7.98 → 8.0 tons
Example 2 — parking area, metric
32 m × 18 m at 60 mm, BBSG at 2,370 kg/m³, 10% buffer.
Volume = 576 × 0.06 = 34.56 m³
Weight = 34.56 × 2,370 = 81,907 kg
Tonnes = 81.91 t
Order = 81.91 × 1.10 = 90.1 tonnes
Example 3 — circular turnaround
30 ft diameter at 3 inches, dense-graded HMA.
Volume = 706.9 × 3 ÷ 12 = 176.7 ft³
Tons = 176.7 × 145 ÷ 2,000 = 12.81 tons
Order with 15% (curved edges) = 14.7 tons
Example 4 — two-lift parking lot
10,000 sq ft, 2 in surface (145 lb/ft³) over 2.5 in binder (147 lb/ft³).
Binder: 10,000 × 2.5 ÷ 12 × 147 ÷ 2,000 = 153.13 tons
Total = 273.96 tons
Order with 10% = 301.4 tons
Example 5 — millings, correct density
1,500 sq ft at 4 inches, RAP at 125 lb/ft³, 15% buffer.
Weight = 500 × 125 = 62,500 lb
Tons = 31.25
Order = 31.25 × 1.15 = 35.9 tons
(At 145 lb/ft³ this would have been 41.6 tons — a 16% over-order.)
Example 6 — road, per kilometre
1,000 m × 7.3 m at 50 mm, dense mix at 2,322.7 kg/m³.
Volume = 7,300 × 0.05 = 365 m³
Tonnes = 365 × 2.3227 = 847.8 t
Order with 10% = 932.6 tonnes
Printable summary
Tons = sq ft × in ÷ 12 × 145 ÷ 2,000
Tonnes = m² × m × 2,322.7 ÷ 1,000
Order = tonnage × 1.10
Densities: HMA 145 · SMA 150 · WMA 143 · OGFC 115 · Porous 100 · RAP 125 · DBM 148 · BBSG 148 · EME 152 lb/ft³
Coverage: 1 ton = 81 sq ft at 2 in · 54 at 3 in · 40 at 4 in
1 ton = 0.907 t · 1 tonne = 1.102 tons · 1 cu yd = 1.96 tons · 1 sq yd = 9 sq ft
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Frequently asked questions
What is the formula for asphalt tonnage?
Tons = Area (sq ft) × Thickness (in) ÷ 12 × Density (lb/ft³) ÷ 2,000. In metric, Tonnes = Area (m²) × Thickness (m) × Density (kg/m³) ÷ 1,000.
What is the asphalt constant?
For dense-graded hot mix in imperial units, 0.006042 tons per square foot per inch. In square yards it is 0.05438. Be careful with the widely circulated 0.0031 figure, which does not correspond to a standard unit combination.
How do I calculate asphalt in metric?
Area in square metres × thickness in metres × 2.3227 = tonnes. So 500 m² at 50 mm is 500 × 0.05 × 2.3227 = 58.1 tonnes.
How do I convert cubic yards to tons of asphalt?
Multiply by 1.96 for dense-graded hot mix. One cubic yard is 27 cubic feet at 145 lb/ft³ = 3,915 lb = 1.96 short tons.
What formula do contractors use?
Most use the long form, because it makes the density assumption explicit and is easy to audit. Estimating software applies the same arithmetic with a mix-specific density from the plant's design sheet.
Sources and further reading
Related calculators and guides
How to calculate
The formulas explained step by step.
Density guide
Density values to substitute.