The bitumen calculation is a short chain in which each step feeds the next. Multiplying length by width gives the surface area; multiplying that area by the compacted thickness gives the volume; and multiplying the volume by the compacted density gives the mass of the whole mixture. The binder is then a percentage of that mass, so the mass is multiplied by the bitumen content and divided by 100. Subtracting the binder from the total leaves the aggregate and mineral filler.
Three of the symbols are measurements you take from the site (length L, width W and compacted thickness T), two come from the mixture itself (the compacted density ρ and the bitumen content P, a percentage of the total mixture mass), and the rest are results: the area A, the compacted volume V, the total mixture mass M, the bitumen binder mass B, and the aggregate and mineral filler remainder G.
The bitumen calculation formulas| Quantity | Formula |
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| Surface area | A = L × W |
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| Compacted volume | V = A × T |
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| Total mixture mass | M = V × ρ |
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| Bitumen binder mass | B = M × (P ÷ 100) |
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| Aggregate and filler remainder | G = M − B |
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| Material cost (optional) | C = M (in the price unit) × price |
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Worked example. A strip 40 m long and 6 m wide has A = 40 × 6 = 240 m². At T = 4 cm = 0.04 m, V = 240 × 0.04 = 9.6 m³. With an illustrative ρ = 2,400 kg/m³, M = 9.6 × 2,400 = 23,040 kg. At P = 5%, B = 23,040 × 5 ÷ 100 = 1,152 kg, and G = 23,040 − 1,152 = 21,888 kg. The full metric, imperial and mixed-unit walk-throughs are in the worked examples above.
Units and compacted density
Keep every length in one unit before you multiply; the calculator converts for you, using exact definitions (1 ft = 0.3048 m, 1 in = 0.0254 m, 1 lb = 0.45359237 kg). The compacted density is a property of the finished, rolled mixture. Pavement Interactive's HMA weight–volume page relates it to the mixture's bulk specific gravity (Gmb): density equals Gmb multiplied by the unit weight of water, about 1,000 kg/m³ or 62.4 lb/ft³, so a compacted mixture with a Gmb of 2.350 has a density of about 2,350 kg/m³. The mix design or the supplier gives Gmb or the density directly; this page does not suggest a value.
How to Calculate Bitumen Quantity for a Road
The bitumen quantity for a road is the mass of binder in the finished asphalt mixture for the area you are paving. It is not measured on its own: you first find the mass of the whole mixture, then take the binder share of it.
Work through it in this order:
- Measure the length and the width of the paved strip, and decide the compacted thickness of the layer you are calculating.
- Multiply length by width for the surface area, then multiply by the compacted thickness for the volume.
- Multiply the volume by the compacted density of the mixture to get the total mixture mass.
- Multiply the total mass by the bitumen content (as a percentage of that total) to get the binder mass.
- Subtract the binder from the total to get the aggregate and mineral filler remainder.
B = L × W × T × ρ × (P ÷ 100)
Worked example. A road section 1 km long and 7 m wide is surfaced with a 50 mm compacted layer. Using an illustrative density of 2,350 kg/m³ and 5% bitumen by total mass: the area is 7,000 m², the volume is 350 m³, and the mixture mass is 822,500 kg, or 822.5 tonnes. The bitumen binder is 41.125 tonnes and the aggregate and filler are 781.375 tonnes.
Layers, irregular areas and exclusions
Calculate each layer of a pavement separately, because each layer has its own thickness, density and binder content. Enter only rectangular strips: for a curved or irregular area, split it into rectangles and add the results, or find the area first with the Square Footage Calculator. The result covers the asphalt mixture itself; it does not include tack coat, prime coat or any base or sub-base material.
How to Calculate Bitumen Content in Asphalt
Bitumen content is the proportion of the asphalt mixture that is bitumen binder, expressed as a percentage. In this calculator, and in the way Pavement Interactive's weight–volume reference defines asphalt content, it is a percentage of the total mixture mass: binder plus aggregate plus any mineral filler.
Pavement Interactive's mix-design reference notes that binder content is also sometimes expressed against the weight of the aggregate alone, and that the two bases give noticeably different numbers for the same mixture. If a specification quotes a binder percentage, check which basis it uses before entering it here.
P = (B ÷ M) × 100
B = M × (P ÷ 100)
Worked example. A mixture has a total mass of 20 tonnes and a binder content of 5% by total mass. The binder is 20 × 5 ÷ 100 = 1 tonne, which leaves 20 − 1 = 19 tonnes of aggregate and mineral filler. Measured against the aggregate alone, that same 1 tonne of binder is 1 ÷ 19 × 100 = 5.263% - the same mixture described on the other basis.
Where the percentage comes from. The bitumen content is a property of the approved mix design, so take it from the project specification or the supplier's mix data. Different mixtures and layers are designed with different binder contents, so one figure should not be reused across a whole pavement.
Bitumen vs Asphalt
The Asphalt Institute's glossary describes asphalt as a dark brown to black cementitious material in which the predominating constituents are bitumens, and treats “bitumen” as a cross-reference to asphalt. It defines asphalt concrete as a carefully controlled mix of asphalt binder and high-quality aggregate that can be compacted into a uniformly dense mass. Pavement Interactive uses “asphalt binder” as the generic term for the binding agent, covering asphalt cement and any material added to modify it.
Put simply, the binder is the sticky bitumen, and the paving material is the finished mixture of that binder with aggregate. This calculator uses the two words that way: bitumen means the binder, and asphalt mixture means the finished paving material made of binder, aggregate and mineral filler.
asphalt mixture mass = bitumen binder mass + aggregate and filler mass
Worked example. One tonne of mixture at 5% bitumen content is 50 kg of bitumen binder and 950 kg of aggregate and filler. If you buy that tonne as a finished mixture, the 50 kg of binder is already inside it.
In practice. Specifications and suppliers do not always use the words in the same way, so when a document says “asphalt” or “bitumen”, work out whether it means the binder alone or the finished mixture before you compare quantities or prices.
How Much Bitumen Is in Asphalt?
An asphalt mixture is mostly aggregate with a comparatively small amount of binder. The Federal Highway Administration's Warm Mix Asphalt FAQs state that aggregates make up about 90–95 percent of the pavement mixture by weight and asphalt binder about 4–8 percent, and Pavement Interactive likewise describes asphalt as typically 4 to 8 percent of the mix by weight.
Because the binder is the smaller share, a small change in binder percentage is a small change in the aggregate share but a large relative change in the binder quantity you need to buy.
aggregate and filler % = 100 − bitumen %
Worked example. At 6% bitumen by total mass, the aggregate and filler are 100 − 6 = 94% of the mixture. In the driveway example above, 29 US tons of mixture at 6% holds 1.74 US tons of binder and 27.26 US tons of aggregate and filler.
What the range does and does not tell you. These sources describe what asphalt mixtures generally contain. They do not give the right binder content for a particular road, driveway or layer; that is set by the mix design for the mixture you are using.
Binder Quantity Reference Table
This table is a mathematical illustration, not a mix-design recommendation. It shows what a given binder percentage means for one metric tonne or one US short ton of finished mixture. The rows run from 4% to 8% in half-percent steps, the span the sources above give for binder in an asphalt mixture by weight; they are arithmetic, not suggested binder contents.
Swipe horizontally to view all columns.
Binder and aggregate quantities per metric tonne and per US short ton of mixture at different binder percentages| Binder (% of total mass) | Binder per tonne (kg) | Aggregate and filler per tonne (kg) | Binder per US ton (lb) | Aggregate and filler per US ton (lb) |
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| 4.0% | 40 | 960 | 80 | 1,920 |
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| 4.5% | 45 | 955 | 90 | 1,910 |
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| 5.0% | 50 | 950 | 100 | 1,900 |
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| 5.5% | 55 | 945 | 110 | 1,890 |
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| 6.0% | 60 | 940 | 120 | 1,880 |
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| 6.5% | 65 | 935 | 130 | 1,870 |
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| 7.0% | 70 | 930 | 140 | 1,860 |
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| 7.5% | 75 | 925 | 150 | 1,850 |
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| 8.0% | 80 | 920 | 160 | 1,840 |
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binder per tonne (kg) = 1,000 × (P ÷ 100)
Worked example. At 5% the table gives 50 kg of binder in a tonne of mixture. For 86.25 tonnes of mixture at 5% that scales to 4,312.5 kg - the calculator does this multiplication for any mass and percentage you enter.
Using the table. Use it to check your sense of scale. To move between the two mass units, the Weight Converter converts tonnes, US tons, kilograms and pounds.
Material Cost Estimation
The material cost the calculator reports is the price of the finished asphalt mixture for the mass you have calculated. It is a materials figure only: it is not the installed cost of the pavement.
Enter the price per unit of finished mixture and say whether that price is per metric tonne (1,000 kg) or per US short ton (2,000 lb). Choose a currency label; it is only a label, and no exchange rate is applied. The cost uses the total mixture mass, because you buy the mixture, and the bitumen is already inside it.
cost = total mixture mass (in tonnes or US tons) × price per tonne or per US ton
Worked example. The metric example above has 86.25 tonnes of mixture at 120 per tonne: 86.25 × 120 = USD 10,350.00. The driveway example has 29 US tons at 95 per US ton: 29 × 95 = USD 2,755.00.
Metric tonne or US short ton?
Check which ton your price uses. The same 86.25-tonne job at a price of 100 is USD 8,625.00 if that price is per metric tonne, but USD 9,507.44 if it is per US short ton, because a short ton is lighter and the same mass is more of them. Do not add a separate binder price on top of a mixture price - that would count the binder twice.
What the estimate leaves out
The estimate has no waste allowance and excludes labour, delivery, laying and compaction, tack coat, sub-base and taxes. For the area itself, you can work in square feet with the Square Footage Calculator, or move between area units with the Area Converter.
This calculator provides material-quantity estimates for planning. It is not a mix design, a pavement design or a supplier quotation, and it does not replace project specifications or a qualified engineer's advice.
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