Asphalt Density — Complete Reference in lb/ft³, kg/m³ and t/m³
Dense-graded hot mix asphalt has a compacted density of 145 lb/ft³, which is 2,322.7 kg/m³ or 2.32 t/m³. This page covers all sixteen common mix types, what makes density vary, the difference between Gmm, Gmb and in-place density, and the standard values used in the US, Europe, France, India, Pakistan and the UK.
Quick answer
Dense-graded hot mix asphalt: 145 lb/ft³ = 2,322.7 kg/m³ = 2.32 t/m³.
That single figure covers most driveway, parking lot and road surfacing work in North America. It is not correct for porous asphalt (about 100 lb/ft³), open-graded friction course (115), recycled millings (125) or French EME 2 (152). The table below has all sixteen.
Density converter
Type in any field and the others update. Default values shown are for dense-graded hot mix asphalt.
Asphalt density by mix type
These are nominal compacted in-place densities — the number you should be feeding into a tonnage calculation. Laboratory maximum densities (Gmm) run 4–6% higher because they contain no air voids.
| 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 |
Two entries in that table deserve a note. Bitumen binder at 65 lb/ft³ is the liquid asphalt cement on its own, not a mix — you would only use it when calculating tack coat or prime coat quantities. EME 2 at 152 lb/ft³ is the densest common paving material, which is precisely the point of it: a high-modulus base course lets a French designer build a thinner structure for the same traffic loading.
Why 145 lb/ft³ is the default
The number is not arbitrary. Work through a typical dense-graded mix design:
- Aggregate bulk specific gravity: about 2.65 — which is what you get from most crushed limestone, granite and gravel sources.
- Binder content: 4.5–6.0% by weight of total mix, with a specific gravity near 1.03.
- Air voids after compaction: 3–5%, with 4% as the design target.
Combine those and the compacted mix lands between 2,300 and 2,350 kg/m³, or 143–147 lb/ft³. Rounding to 145 gives an estimating figure that is within about 1.5% of reality for the great majority of dense-graded mixes, which is comfortably inside any sensible waste buffer.
Where it breaks down is with unusual aggregate. Basalt and traprock have specific gravities near 3.0 and produce mixes at 150–155 lb/ft³. Lightweight expanded shale aggregate goes the other way. If you are working with a local aggregate you do not know, ask the plant for the mix design sheet — it will state the Gmm directly.
What changes asphalt density
Aggregate specific gravity
Aggregate is 94–95% of the mix by weight, so its density essentially is the mix density. This is the largest single variable and it is entirely geological — the same mix design in two different quarries can differ by 5%.
Binder content
Bitumen has a specific gravity around 1.03, considerably lighter than aggregate. A mix at 6.5% binder is measurably less dense than the same aggregate at 4.5%. SMA carries high binder content but compensates with stone-on-stone contact and dense aggregate, which is why it ends up at 150 lb/ft³ rather than lower.
Air void content
This is the variable you control on site. Every percentage point of air voids removes roughly 1% of the density. A dense-graded surface course designed at 4% voids and compacted to 8% is 4% lighter than specified — and considerably shorter-lived, because interconnected voids let water and air into the mat.
Gradation
Dense continuous gradations pack tightly. Gap-graded and open-graded mixes leave deliberate voids: open-graded friction course is designed at 15–22% voids and porous asphalt at 18–25%, which is why they weigh 100–115 lb/ft³ instead of 145.
Compaction effort
The single largest field variable. A mat rolled while too cold, or with too few passes, never reaches design density. Most specifications require 92–96% of Gmm, and contractors are paid or penalised against that number.
Recycled content
Blended RAP at 15–30% changes almost nothing, because the aggregate and reactivated binder behave like virgin material. Standalone millings used as a surfacing are different — they are compacted aged material that never re-melts, and they sit around 125 lb/ft³.
Loose, compacted and theoretical maximum
Three different densities get quoted for the same material, and confusing them is the most common technical mistake in asphalt estimating.
| Term | Symbol | Typical value | What it means | When you use it |
|---|---|---|---|---|
| Theoretical maximum specific gravity | Gmm | 2.45–2.55 | Density with zero air voids, measured in the lab under vacuum (AASHTO T 209) | Compaction acceptance, expressed as %Gmm |
| Bulk specific gravity of compacted mix | Gmb | 2.30–2.42 | Density of a compacted core or gyratory specimen (AASHTO T 166) | Mix design and QC |
| In-place compacted density | — | 140–150 lb/ft³ | What is actually on the ground after rolling | Tonnage calculation and ordering |
| Loose density | — | 115–125 lb/ft³ | Uncompacted mix behind the paver or in a stockpile | Almost never — do not order against this |
The practical rule: always calculate tonnage against in-place compacted density and compacted thickness. If someone quotes you a loose thickness, divide it by the compaction factor — about 1.20 for dense-graded HMA — before you calculate.
Density by country standard
United States — AASHTO and state DOTs
Superpave mix design under AASHTO M 323 governs most work. Density is specified as a percentage of Gmm rather than an absolute figure, typically 92–96% for mainline paving. Individual state DOTs publish approved mix designs with the Gmm stated. For estimating, 145 lb/ft³ is the universal working assumption.
Europe — EN 13108
The EN 13108 series covers asphalt concrete (part 1), SMA (part 5), hot rolled asphalt (part 4) and porous asphalt (part 7). Density is stated in kg/m³ and design void content is generally tighter than US practice, which is part of why European dense mixes run slightly heavier at 2,350–2,400 kg/m³.
France — BBSG, BBME, GB and EME
French designations describe the layer function as well as the material. BBSG (béton bitumineux semi-grenu) is the standard 0/10 surface course at about 2,370 kg/m³. BBME uses modified binder for high-traffic surfaces at about 2,400 kg/m³. Grave bitume (GB2 to GB4) is the asphalt-treated base at around 2,385 kg/m³. EME 2 is the high-modulus base course at 2,435 kg/m³ — the densest material in common use.
India — MoRTH: BC, DBM, BM and premix
The MoRTH Specifications for Road and Bridge Works define the standard layers. Bituminous Concrete (Clause 509) is the surface course at about 2,355 kg/m³. Dense Bituminous Macadam (Clause 507) is the binder/base course at about 2,370 kg/m³. Bituminous Macadam (Clause 504) is more open-graded and lighter at roughly 2,160 kg/m³. Premix carpet, a thin open-graded surfacing, is lighter again. Binder is specified by viscosity grade — VG-30 and VG-40 are the common paving grades.
Pakistan — NHA General Specifications
NHA work uses penetration-grade binder, most commonly 60/70 for the majority of the country and 80/100 in the colder northern regions. Asphaltic concrete wearing course density is comparable to dense-graded HMA at 2,300–2,370 kg/m³. Marshall mix design remains the standard method.
United Kingdom — BS 594987 and BS EN 13108
UK practice calls the material asphalt or macadam; "tarmac" is colloquial. Dense asphalt concrete surface course runs about 2,320–2,400 kg/m³. Hot rolled asphalt, the traditional UK surfacing with pre-coated chippings rolled in, is slightly lighter at around 2,290 kg/m³.
Using density in a tonnage calculation
Density is the bridge between volume and weight, and it is the only place a mix-specific number enters the calculation:
Everything else in the equation is geometry. Get the density right and the rest is arithmetic. Here is what the same 1,000 sq ft driveway at 3 inches costs you in tonnage across different mixes:
| Mix type | Density | Volume | Tonnage (no buffer) | Difference vs HMA |
|---|---|---|---|---|
| Porous asphalt | 100 lb/ft³ | 250 ft³ | 12.5 tons | −31% |
| Open-graded friction course | 115 lb/ft³ | 250 ft³ | 14.4 tons | −21% |
| RAP millings | 125 lb/ft³ | 250 ft³ | 15.6 tons | −14% |
| Cold mix | 140 lb/ft³ | 250 ft³ | 17.5 tons | −3% |
| Dense-graded HMA | 145 lb/ft³ | 250 ft³ | 18.1 tons | baseline |
| DBM | 148 lb/ft³ | 250 ft³ | 18.5 tons | +2% |
| SMA | 150 lb/ft³ | 250 ft³ | 18.8 tons | +3% |
| EME 2 | 152 lb/ft³ | 250 ft³ | 19.0 tons | +5% |
At $130 per ton, the gap between the porous and the EME assumption on this small job is $845. On a 10,000 sq ft lot it is $8,450. Use the density calculator or select your mix in any calculator on this site.
Density-related conversions
| Question | Answer (dense-graded HMA) | Formula |
|---|---|---|
| How many m³ in one tonne? | 0.4305 m³ | 1 ÷ 2.3227 |
| How many tonnes in one m³? | 2.3227 t | density ÷ 1,000 |
| How many ft³ in one US ton? | 13.79 ft³ | 2,000 ÷ 145 |
| How many cubic yards in one ton? | 0.511 cu yd | 2,000 ÷ 145 ÷ 27 |
| How much does 1 m³ weigh? | 2,322.7 kg | density × volume |
| How much does 1 ft³ weigh? | 145 lb | density × volume |
| 1 tonne covers how many m² at 50 mm? | 8.61 m² | 0.4305 ÷ 0.05 |
| 1 tonne covers how many m² at 40 mm? | 10.76 m² | 0.4305 ÷ 0.04 |
| 1 ton covers how many sq ft at 2 in? | 82.7 sq ft | 13.79 ÷ 0.1667 |
| 1 tonne of bitumen binder in m³ | 0.96 m³ | 1 ÷ 1.0412 |
Measuring density in the field
Nuclear density gauge
A sealed gamma source measures backscatter through the mat and reports density in seconds. Fast, non-destructive and the traditional standard, but it requires a licensed operator, regulated transport and periodic calibration against cores.
Core sampling
A 4 or 6 inch core is cut, dried and weighed in air and water to obtain Gmb, then compared against the lab Gmm. This is the referee method — slower, destructive, and definitive. Most specifications allow gauge readings for process control and require cores for acceptance.
Non-nuclear gauges
Electrical impedance devices avoid the regulatory burden entirely. They need site-specific calibration against cores to be reliable, but on a long project that calibration pays for itself.
Intelligent compaction
Roller-mounted accelerometers and GPS map coverage and stiffness across the whole mat rather than at spot checks. Increasingly specified on large highway contracts, where the value is in catching under-rolled areas rather than in the absolute density number.
Frequently asked questions
What is the density of asphalt in kg/m³?
Dense-graded hot mix asphalt has a nominal compacted density of 2,322.7 kg/m³. That is the metric equivalent of the 145 lb/ft³ figure used throughout North America. Expressed as t/m³ it is 2.32.
What is the density of asphalt in lb/ft³?
145 lb/ft³ for dense-graded hot mix. Real-world in-place values run 140 to 150 lb/ft³ depending on aggregate specific gravity, binder content and how well the mat was compacted.
Why is 145 lb/ft³ used as the standard?
It is the round-number result of a typical dense-graded mix: aggregate with a bulk specific gravity near 2.65, about 5% binder by weight, and 4% air voids after compaction. Work that through and you land at 2,320–2,330 kg/m³. It has been the estimating default in North America for decades because it is close enough for ordering purposes across the majority of dense-graded mixes.
What is the density of asphalt millings?
Around 125 lb/ft³ (2,002 kg/m³) compacted, and as low as 100–110 lb/ft³ loose in a stockpile. Millings never re-bond the way fresh hot mix does, so they retain more voids. Using 145 for millings overstates the tonnage by roughly 16%.
What is Gmm and how does it differ from in-place density?
Gmm is the theoretical maximum specific gravity — the density the mix would have with zero air voids, measured in the lab under vacuum. Gmb is the bulk specific gravity of a compacted specimen. Field compaction is reported as %Gmm, and the usual acceptance target is 92–96%. In-place density is therefore always below Gmm by the air void content.
Does asphalt density change with temperature?
Yes, though not enough to matter for ordering. Hot mix at 300 °F is a few percent less dense than the same material at 70 °F because the binder expands. What actually changes your tonnage is compaction state, not temperature.
What is the density of BBSG and other French mixes?
BBSG 0/10 runs about 2,370 kg/m³, BBME about 2,400 kg/m³, grave bitume around 2,385 kg/m³ and EME 2 about 2,435 kg/m³. French mixes are generally denser than the North American dense-graded default because of lower design void content and higher aggregate density.
What is the density of DBM and BC in India?
Under MoRTH specifications, Dense Bituminous Macadam sits around 2,370 kg/m³ and Bituminous Concrete around 2,355 kg/m³. Bituminous Macadam, being more open-graded, is lighter at roughly 2,160 kg/m³. Premix carpet is lighter still.
How do I convert lb/ft³ to kg/m³?
Multiply by 16.0185. So 145 × 16.0185 = 2,322.7 kg/m³. Going the other way, divide kg/m³ by 16.0185. There is a live two-way converter at the top of this page.
How many cubic metres is one tonne of asphalt?
0.43 m³ for dense-graded hot mix at 2,322.7 kg/m³ — the reciprocal of 2.3227 t/m³. For porous asphalt at 1,602 kg/m³ a tonne occupies 0.62 m³.
What density should I use for tarmac in the UK?
UK dense-graded asphalt concrete to BS EN 13108-1 runs about 2,320–2,400 kg/m³, essentially the same as North American dense-graded mix. Hot rolled asphalt is slightly lighter at around 2,290 kg/m³.
Does higher RAP content change the density?
Marginally. A mix with 20–30% recycled content behaves almost identically to virgin mix once compacted, because the aged binder is reactivated and the aggregate is the same material. Loose millings used as a standalone surfacing are a different matter — those are the 125 lb/ft³ case.