Tarmac Calculators
Professional estimation tools for paving and surfacing projects. Accurately calculate tarmac quantities, estimate driveway installation and repair costs, and determine sub-base material requirements for your project.
Last updated: · Reviewed by the OtherCalculators editorial team
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Which tarmac calculator do you need?
- I'm laying a brand-new tarmac driveway and need a budget
- Tarmac Driveway Cost Calculator — materials, sub-base and labour for a full new drive, by area
- I need to know how many tonnes of tarmac to order
- Tarmac Quantity Calculator — converts area and compacted depth to tonnage at your mix density
- My drive is cracked or potholed and I want repair costs
- Tarmac Repair Cost Calculator — prices patching, resurfacing and full replacement side by side
- I'm building the foundation and need sub-base material
- Tarmac Sub-Base Calculator — MOT Type 1 tonnage for a stable, load-bearing base
- I'm surfacing a car park, path or private road, not a drive
- Tarmac Surface Cost Calculator — rates for larger and specialised surfacing jobs
Available Tarmac Tools
5 Calculators AvailableTarmac Driveway Cost Calculator
Estimate the comprehensive cost of laying a new tarmac driveway.
Tarmac Quantity Calculator
Calculate required hot mix tarmac tonnage and volume.
Tarmac Repair Cost Calculator
Estimate costs for tarmac patching, resurfacing, or replacement.
Tarmac Sub-Base Calculator
Calculate MOT Type 1 aggregate needs for a structurally sound sub-base.
Tarmac Surface Cost Calculator
Calculate specialized tarmac surfacing costs for car parks, pathways, and private roads.
What this category covers
These tools estimate tarmac paving in UK terms — square metres, tonnes and pounds — for domestic and light-commercial surfacing. Between them they cover the whole job: how much surfacing material and sub-base to order, and what a new drive, a repair, or a larger surface is likely to cost. "Tarmac" here means the hot-laid dense bituminous macadam most UK contractors still call tarmac; it is the same material and the same arithmetic as hot-mix asphalt.
What is not here: concrete, block paving, resin-bound and gravel surfaces, and the structural design of roads carrying heavy traffic. The figures assume a standard domestic build-up on prepared ground, so a job with unusual loading, poor drainage or a failing base needs a contractor's assessment rather than an estimate. For the same work priced in US tons and dollars, see the asphalt calculators.
How these calculations work
Every quantity on a tarmac job comes from the same chain. Area × compacted depth gives a volume in cubic metres. Volume × density converts that to the tonnes you actually order — and density is the one figure worth getting right, because compacted dense tarmac is taken as about 2.4 t/m³ while the granular sub-base beneath it is a different material at a different density, ordered separately. Enter the compacted (finished) depth, not the loose laid depth: hot tarmac is rolled down by roughly 20–25%, and the 2.4 t/m³ figure already assumes it has been rolled.
Cost then comes from one of two routes. Quantity-based pricing multiplies the tonnage by a supply rate; area-based pricing multiplies the square metres by an all-in rate that already folds in labour, plant and sub-base. That is why a per-square-metre quote is only meaningful once you know the tarmac depth and sub-base depth it assumes — a thinner specification is a cheaper number for a shorter-lived drive, not a better deal.
The standard domestic driveway build-up
Most of the calculators here assume this build-up, and it is the specification to compare a quote against. The finished tarmac is thinner than people expect; the depth that does the structural work is the sub-base underneath it. An impermeable front-garden drive over five square metres can need planning permission or a permeable design under UK rules, which the Planning Portal sets out.
| Layer | Typical compacted depth | Material |
|---|---|---|
| Surface (wearing) course | 25–30 mm | Fine dense tarmac |
| Binder (base) course | 50 mm | Coarser dense tarmac |
| Finished tarmac, total | ≈ 75 mm | 50 mm binder + 25–30 mm surface |
| Sub-base | ≈ 150 mm | Compacted MOT Type 1 aggregate |
Choosing between the tools
The split is between ordering materials and pricing a job. If you already know your specification, the quantity and sub-base tools turn dimensions into tonnes to order. If you are still budgeting, the cost tools work from area and a rate — the driveway tool for a full new install, the repair tool to compare patch against resurface against replace, and the surface tool for car parks, paths and private roads that are priced differently from a domestic drive.
Pricing a job3 tools
Ordering materials2 tools
Common mistakes when estimating tarmac
- Entering loose depth instead of compacted depth. Tarmac is laid thick and rolled down. Enter the finished depth you want; the standard 2.4 t/m³ density already accounts for the compaction.
- Ordering the exact calculated tonnage. Add 5–10% for wastage, edge spillage and unrecoverable material, and round up to the supplier's delivery increment. A part-load shortfall stops the job.
- Skimping on the sub-base. A driveway is only as strong as its foundation. Under-specifying the MOT Type 1 depth or its compaction is the usual cause of rutting and cracking — check it with the tarmac sub-base calculator before you order the surfacing.
- Confusing tarmac tonnage with sub-base tonnage. They are different materials at different densities, ordered separately. Estimating one from the other over- or under-orders both.
- Ignoring drainage and falls. A surface with nowhere to shed water fails early, whatever it cost. Design in a slope or linear drainage — and remember an impermeable front-garden drive may need permission or a permeable build-up.
- Comparing per-m² quotes without the depth. A rate is meaningless until you know the tarmac and sub-base depths it assumes. Put every quote on the same specification before comparing the price.
Tarmac and paving FAQs
What is the difference between tarmac and asphalt?+
While frequently used interchangeably, true tarmac (tarmacadam) relies on a tar-based binder, whereas asphalt uses bitumen—a petroleum by-product. Modern paving almost universally uses asphalt (bitumen macadam or SMA) due to superior durability and environmental safety, even though contractors still colloquially refer to it as 'tarmacking'.
How do I calculate how much tarmac I need?+
To calculate tarmac tonnage, you multiply the surface area (length × width) by the desired compacted depth to find the volume, then multiply by the material's density (typically 2.3 to 2.4 tonnes per cubic meter). Always add a 5% to 10% wastage factor to account for site irregularities.
How thick should a tarmac driveway be?+
A standard domestic driveway typically features a 50mm base course (binder course) topped with a 25mm to 30mm surface course (wearing course), bringing the total tarmac thickness to roughly 75mm to 80mm. This sits upon a compacted MOT Type 1 sub-base, usually 150mm thick.
Is it cheaper to repair or replace a tarmac driveway?+
Patching small potholes or cracks is significantly cheaper than replacing. If the structural integrity of the base is sound, an 'overlay' or 'resurfacing' (adding a new surface layer) offers a middle-ground cost. Full replacement is the most expensive but is necessary if the sub-base is failing or the surface is extensively crazed.
What is MOT Type 1 and why do I need it?+
MOT Type 1 is a granular aggregate sub-base material (often crushed stone or concrete) that compacts to create a highly stable, load-bearing layer. A strong sub-base is essential under tarmac to prevent the surface from sinking, rutting, or cracking under vehicle weight.
How do I estimate a tarmac driveway job from start to finish?+
Work it as a chain. First set the compacted depth — about 75mm of tarmac (a 50mm binder course under a 25–30mm surface course) on roughly 150mm of MOT Type 1 sub-base for a domestic drive. Multiply your area by each depth to get the volume of tarmac and of sub-base, convert both to tonnes using their densities (tarmac is about 2.4 t/m³), add 5–10% wastage, then price the tonnage or the area against a rate. The quantity, sub-base and cost calculators below each handle one link of that chain.
Why do two tarmac quotes for the same driveway differ so much?+
Usually because they assume different specifications, not different prices. A quote that lays a thinner surface course, skimps on sub-base depth, omits edgings or drainage, or reuses the existing base will be cheaper and shorter-lived. Compare the compacted tarmac thickness, the sub-base depth and what groundwork is included before comparing the headline figure — a per-square-metre rate means little until you know the depth it assumes.
Related categories
- Asphalt Calculators (25) — the same material and the same area × depth × density method, priced in US tons and dollars per square foot rather than UK tonnes and pounds per m² — the right category if your job is in the United States
- General Calculators (4) — the standalone MOT Type 1 sub-base calculator and the bitumen calculator for binder and spray quantities, which sit outside the tarmac category but feed the same driveway build-up
Estimates & assumptions
- Tonnages assume about 2.4 t/m³ for compacted dense tarmac. Open-graded and heavy-duty mixes differ, so confirm the density of your specific mix with the supplier.
- Enter compacted (finished) depth, not the loose laid depth. Hot tarmac is rolled down by roughly 20–25%, which the standard density already accounts for.
- The MOT Type 1 sub-base is ordered separately, at a different density from the tarmac, and its depth depends on ground conditions and expected traffic.
- Cost figures are planning estimates. UK prices vary by region, access, ground conditions and contractor, and change over time — always obtain itemised quotes.
- These tools do not model drainage design, edgings, or planning permission. An impermeable front-garden drive over five square metres may need permission or a permeable build-up; check the Planning Portal.
These tools produce estimates for planning only. They are not a quotation. Confirm every figure and every specification with your contractor and supplier before ordering.