What is the basic asphalt volume formula?

Volume = length × width × depth, with all three dimensions in the same unit. In US practice that means feet: divide the result by 27 for cubic yards, or multiply by 145 lb/ft³ and divide by 2,000 for tons. Metric users multiply meters directly and read cubic meters.

How do I calculate asphalt volume for an irregular shape?

Decompose it. Any straight-edged footprint splits into rectangles and triangles; curved features are circles or circle segments. Compute each piece with its own formula, sum the areas, then multiply once by depth. Two shapes cover 95% of driveways; three cover almost everything.

Does the formula use loose or compacted depth?

Compacted depth — the finished pavement thickness on the drawings. Density (145 lb/ft³) already accounts for the compacted state when you convert to tons. If you instead measure a loose windrow at about 117 lb/ft³, you are in a different bookkeeping system; never mix the two.

How do I convert the volume result to tons?

Multiply cubic feet by 145 and divide by 2,000, or take the shortcut: cubic yards × 1.96. A 170 ft³ takeoff is 170 × 145 ÷ 2,000 = 12.3 tons. Metric: cubic meters × 2.32 gives tonnes.

Is the asphalt formula different from the concrete formula?

No — volume is material-blind. Length × width × depth works identically for both; only the density constant and the order unit change. If you have run a concrete takeoff, an asphalt takeoff is the same worksheet with 145 lb/ft³ substituted for concrete's 150.

Asphalt · Volume Guide

The asphalt volume formula

Three formulas — rectangle, circle, triangle — dispatch every paving footprint you will ever measure. The formulas are trivial; the unit discipline around them is where takeoffs go wrong.

Contents

1.The rectangle formula
2.Circles and triangles
3.The three unit traps
4.Worked example: L-shaped driveway
5.Worked example: circular cul-de-sac

The rectangle formula

Formula

V = L × W × D

L, W: length and width in feet
D: compacted depth in feet (inches ÷ 12; 4 in = 0.333 ft)
V: cubic feet — ÷ 27 for yd³, × 145 ÷ 2,000 for tons

This one formula, applied to decomposed pieces, handles nearly every job. Metric: meters in, cubic meters out, × 2.32 for tonnes.

The method is identical for concrete — how to calculate concrete walks the same five steps with a different density — so a takeoff skill learned on one material transfers whole to the other.

Circles and triangles

Formula

V = π × r² × D

r: radius in feet (half the diameter)
D: depth in feet

Cul-de-sacs, turnarounds, tank pads. Half and quarter circles: multiply by 0.5 or 0.25.

Formula

V = ½ × b × h × D

b: triangle base in feet
h: height perpendicular to the base

Entrance flares, tapers and skewed corners — measure h square to b, not along the slanted edge.

Matching real features to formulas. Compute areas first, then multiply the total once by depth.
Site feature	Shape to use	Area formula
Driveway run, pad, lane	Rectangle	L × W
Cul-de-sac, turnaround	Circle	π × r²Half circle: × 0.5
Entrance flare, taper	Triangle	½ × b × h
L or T footprint	Two+ rectangles	Sum of L × W piecesSplit at inside corners
Curved edge	Averaged rectangle	Avg width × lengthWidth stations every 10 ft

The three unit traps

Worked example: L-shaped driveway

Worked example

An L-shaped driveway: a 40 × 12 ft main run plus a 20 × 10 ft parking leg, paved 3 in thick.

1
Split at the inside corner
Rectangle A: 40 × 12 = 480 ft² · Rectangle B: 20 × 10 = 200 ft²
2
Total area
480 + 200 = 680 ft²
3
Volume at 3 in (0.25 ft)
680 × 0.25 = 170 ft³
4
Cubic yards
170 ÷ 27 = 6.3 yd³
5
Tons for the plant
170 × 145 ÷ 2,000 = 12.3 tons

Result: 6.3 yd³ geometric — order about 13 tons with a 5% waste allowance.

Worked example: circular cul-de-sac

Circular cul-de-sac

A 40 ft diameter turnaround paved 3 in thick. One circle formula, no decomposition needed.

1
Radius
40 ÷ 2 = 20 ft
2
Area
π × 20² = 1,256.6 ft²
3
Volume at 3 in (0.25 ft)
1,256.6 × 0.25 = 314.2 ft³
4
Cubic yards
314.2 ÷ 27 = 11.6 yd³
5
Tons
314.2 × 145 ÷ 2,000 = 22.8 tons

Result: 11.6 yd³ — call the plant for 24 tons with waste included.

Frequently asked questions

What is the basic asphalt volume formula?: Volume = length × width × depth, with all three dimensions in the same unit. In US practice that means feet: divide the result by 27 for cubic yards, or multiply by 145 lb/ft³ and divide by 2,000 for tons. Metric users multiply meters directly and read cubic meters.
How do I calculate asphalt volume for an irregular shape?: Decompose it. Any straight-edged footprint splits into rectangles and triangles; curved features are circles or circle segments. Compute each piece with its own formula, sum the areas, then multiply once by depth. Two shapes cover 95% of driveways; three cover almost everything.
Does the formula use loose or compacted depth?: Compacted depth — the finished pavement thickness on the drawings. Density (145 lb/ft³) already accounts for the compacted state when you convert to tons. If you instead measure a loose windrow at about 117 lb/ft³, you are in a different bookkeeping system; never mix the two.
How do I convert the volume result to tons?: Multiply cubic feet by 145 and divide by 2,000, or take the shortcut: cubic yards × 1.96. A 170 ft³ takeoff is 170 × 145 ÷ 2,000 = 12.3 tons. Metric: cubic meters × 2.32 gives tonnes.
Is the asphalt formula different from the concrete formula?: No — volume is material-blind. Length × width × depth works identically for both; only the density constant and the order unit change. If you have run a concrete takeoff, an asphalt takeoff is the same worksheet with 145 lb/ft³ substituted for concrete's 150.

Let the calculator carry the units

Rectangle, feet, inches or meters — the volume calculator applies these formulas with the conversions handled.

Asphalt Volume Calculator

Next in the volume series

Measurement Guide Density & Volume Unit Conversion

Sources & references

[1]MS-4: The Asphalt Handbook, 7th ed. — Asphalt Institute, 2007
[2]Asphalt Pavement Design Guide (APD-1) — National Asphalt Pavement Association, 2020