Asphalt Guides and Reference
In-depth reference on asphalt density, thickness, pavement structure, mix types and the calculations behind every estimate, with sources from NAPA, AASHTO, FHWA and the relevant national standards.
All 7 guides
Asphalt density
The complete density reference: 16 mix types in lb/ft³, kg/m³ and t/m³, what makes density vary, and Gmm versus in-place density.
Asphalt thickness
Compacted depths for driveways, lots and roads, aggregate base by soil CBR, and the lift-thickness rule that governs single-pass paving.
Road layers
All five pavement layers explained — wearing course to subgrade — with materials, thicknesses, tack coats and failure modes.
How to calculate asphalt
The tonnage method step by step in both unit systems, with worked examples and a warning about incorrect shortcut constants.
Tonnage formula
Every formula, constant and conversion on one printable page, with six worked examples.
Asphalt mix types
HMA, WMA, cold mix, SMA, open-graded, porous and RAP compared, plus French, Indian, UK and Pakistani designations.
Asphalt vs concrete
Installed cost, 40-year lifecycle totals, climate performance, repairability and which to choose.
Where to start
| If you are… | Read |
|---|---|
| Working out how much to order | How to calculate asphalt |
| Deciding how thick to build | Asphalt thickness guide |
| Specifying a full road structure | Asphalt road layers |
| Choosing between mixes | Asphalt mix types |
| Checking a density value | Asphalt density |
| Deciding between asphalt and concrete | Asphalt vs concrete |
| Looking for a formula quickly | Tonnage formula |
The essentials in one place
Density
Dense-graded hot mix asphalt: 145 lb/ft³ = 2,322.7 kg/m³ = 2.32 t/m³. That figure is correct for standard paving and wrong for porous asphalt (100), open-graded friction course (115), RAP millings (125) and several regional mixes. Full table in the density guide.
Thickness
Residential driveways 2–3 in, commercial drives 4–5 in, parking lots 3–8 in by zone, municipal roads 6–8 in, highways 8–12 in — all over 4–18 in of aggregate base depending on subgrade. Detail in the thickness guide.
Formula
Tonnes = Area (m²) × Thickness (m) × Density ÷ 1,000
Coverage
One ton covers about 81 sq ft at 2 in, 54 at 3 in and 40 at 4 in.
How to use these guides together
Most paving estimates follow the same chain of decisions, and each guide covers one link in that chain. You start by fixing the thickness, because depth drives every downstream number: our thickness guide gives compacted depths by application, and the road layers guide explains why a heavy-duty pavement needs a binder course and a thick aggregate base rather than one deep lift of surface mix. Once depth is set, you pick a mix, and the mix types guide maps the choice — dense-graded HMA for most work, SMA for heavy loads, open-graded or porous where drainage matters, cold mix for patching — onto the density you should feed the calculator.
With depth, mix and area in hand, the calculation guide and the one-page tonnage formula turn those inputs into tons, tonnes and cubic yards. If you are still deciding whether asphalt is the right material at all, the asphalt versus concrete comparison weighs installed cost against forty-year lifecycle cost, repairability and climate performance before you commit. Read in that order — thickness, layers, mix, calculation, cost — and every figure you enter into a calculator will have a documented reason behind it.
Why published numbers vary
Ask three sources for "the density of asphalt" and you will get three answers, and that is not because any of them is wrong. Density depends on aggregate mineralogy, binder content, air-void target and how hard the mix is compacted, so a dense-graded surface course can legitimately run anywhere from about 142 to 148 lb/ft³. We publish 145 lb/ft³ as the working default because it is the figure AASHTO, most state DOTs and the asphalt industry use for estimating, but every guide states the range and the source so you can substitute a local value when your supplier gives you a mix design. The same caution applies to thickness: the depths in our guides are typical specifications, not a substitute for a pavement design signed by an engineer on a project where loading, subgrade and drainage are known.
Prices move even faster. Asphalt is roughly five percent liquid bitumen by weight, and bitumen tracks crude oil, so the per-ton price you were quoted last season may not hold this one. That is why the calculation guides deliberately separate the quantity you need, which is a physical fact, from the cost, which is a moving market number best checked against the current figures in our cost section. Treat the guides as the stable reference for how asphalt behaves, and the cost pages as the live layer on top.
Sources and standards
The density, thickness and mix-design figures throughout these guides are drawn from the National Asphalt Pavement Association (NAPA), the American Association of State Highway and Transportation Officials (AASHTO), the Federal Highway Administration (FHWA) and the Asphalt Institute, cross-checked against national standards where a page is localized — the French NF EN 13108 series and CEREMA guidance, the UK's BS 594987 and BS EN 13108, India's MoRTH Specifications for Road and Bridge Works, and Pakistan's NHA General Specifications. Each individual guide lists the specific references it relies on so you can verify a value at source rather than taking ours on trust.
Related calculators and guides
Calculators
Apply the guidance to your project.
Glossary
Terminology defined.
Asphalt prices
Current per-ton and installed cost figures.
Common questions
Direct answers to the questions people ask most.