How many parking bays can I fit?

A standard UK parking bay is 2.4m wide × 4.8m long (BS 8300). Approximately 65% of total car park area provides usable parking — the remainder is aisles (6m wide for 90° bays), access roads and turning areas. For a rough estimate: bays = (Total Area × 0.65) / (2.4 × 4.8). Disabled bays are 3.6m wide.

What sub-base depth for a car park?

Sub-base depth depends on traffic loading: light use (cars only) = 150mm, medium (cars + vans) = 225mm, heavy (HGV access) = 350mm or more. Use Type 1 sub-base (crushed limestone/granite) compacted in 150mm layers. A CBR test on the subgrade will confirm the exact depth needed for your site's soil conditions.

How much does car park line marking cost?

Thermoplastic line marking costs approximately £2.50-5.00 per linear metre for standard white or yellow lines. Each bay requires marking on 3 sides (two lengths + one width = approximately 12m per bay). Additional markings include disabled symbols, directional arrows, hatching, and text. Budget £3-4 per metre for standard markings.

What drainage is needed for a car park?

Car parks need surface water drainage with falls of 1:60 to 1:80 to channel drains or gullies. Linear drainage channels are typically spaced every 15-20m. Under current regulations, car park drainage often needs a petrol/oil interceptor before connecting to the surface water sewer. SuDS solutions (permeable paving, swales) may be required.

What surface is best for a car park?

Tarmac is the most common and cost-effective option (£25-45/m²). Block paving is more attractive but costlier (£40-70/m²) and easier to repair. Concrete is durable but expensive (£50-80/m²). Cellular gravel grids offer a permeable option for overflow or low-use areas. For commercial car parks, tarmac with proper sub-base is usually the best value.

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Car Park Surfacing Calculator — Bays, Sub-base & Markings

Calculate parking bay count, sub-base by traffic loading, line marking and drainage for car park construction.

Total Car Park Area

Surface Type

Traffic Level

Sub-base: 150mm

Surface Price

Sub-base Price

Marking Price

Drainage Channel Price

How We Calculate This

This calculator estimates parking bay count, sub-base quantities, line marking and drainage channel requirements for a car park.

Bay count

Bays = floor((Total Area × 0.65) / (Bay Width × Bay Length))
65% efficiency accounts for aisles, access roads and turning areas. Standard UK bay: 2.4m × 4.8m with 6m aisle width.

Sub-base

Tonnes = Area × Depth(m) × 1.8 t/m³ × (1 + Wastage%)
Depth by traffic: 150mm (light), 225mm (medium), 350mm (heavy).

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.