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Groundworks · blocks · sand · sub base
How many paving blocks do I need for a driveway?
Blocks, the sharp-sand laying course, kiln-dried jointing sand, the Type 1 under it and the kerbs along the open edges, with a price at the bottom. Blocks are laid tight together, so the block’s face is what it covers.
Measure it
Every box has its own unit next to it.
Change the unit beside any box and the number converts. The (i) beside each question says what the box wants and where the figure usually comes from. Anything marked per cent is a percentage of the quantity above it.
Check the rates
Rates and assumptions used
These are the figures the calculator works to. Change any of them and the order list updates — your merchant’s pack sizes and your own waste allowances beat the defaults every time.
Order list
The orange figure is the one you order to. Highlighted rows are the other numbers you order to. The small print under each row is the sum that produced it, so you can check it against your own take-off. Amber rows are warnings, not quantities.
How this one works
- Blocks =
area ÷ (block length × block width) × (1 + cutting %) - Laying course =
area × sand depth × sand density - Jointing sand =
area × kg per m² - Sub base =
area × sub-base depth × density × (1 + waste %) - Edging kerbs =
open edge ÷ kerb length, rounded up - Cost =
area × block price per m² × (1 + cutting %) + area × laying rate
The figures the calculator works to. Every one can be changed in step 2, and your merchant’s pack sizes and your own waste allowances beat these defaults every time.
| Rate | Default | Why |
|---|---|---|
| Sharp sand density | 1.6 t/m³ | Loose sharp sand. |
| Jointing sand | 3 kg/m² | Kiln-dried sand brushed into the joints. Check the bag: it varies with the block and the joint. |
| Sub-base density | 2.1 t/m³ | MOT Type 1 compacted. |
| Sub-base waste | 5 % | |
| Edging kerb length | 0.915 m | One edging kerb. Many are 915 mm long; set yours. |
| Bulk bag weight | 0.85 t | A standard merchant bulk bag. |
A worked example
With the defaults the page opens on:
- How long is the drive? 10 metres
- How wide is it? 5 metres
- Which block size? 200 × 100
- How much spare for cuts? 5 per cent
- How deep is the sand laying course? 40 millimetres
- How deep is the sub base once compacted? 150 millimetres
- How many metres of open edge need a kerb? 0 metres
- What do the blocks cost per m²? £22.00
- What is the laying rate? 35 £/m²
Blocks
- Area: 50 m² — L × W
- Blocks per m²: 50 no. — 1 ÷ (200 × 100 mm)
- Cutting waste: 5 %
- Blocks to order: 2,625 no. — area ÷ one block, +5%
Sand, sub base and kerbs
- Sharp sand, laying course: 3.2 t — 40 mm × 1.6 t/m³
- Sharp sand bulk bags: 4 bags — at 0.85 t a bag
- Kiln-dried jointing sand: 150 kg — at 3 kg/m²
- Type 1 sub base: 16.54 t — 150 mm × 2.1 t/m³, +5%
- Type 1 bulk bags: 20 bags — at 0.85 t a bag
- Edging kerbs: 0 no. — no open edge entered
Budget
- Blocks: £1,155
- Laying: £1,750
- Blocks + laying: £2,905 — excludes sand, sub base, kerbs and VAT
Change any figure above and every line recalculates; the small print under each row is the sum that produced it.
Questions people ask
How many paving blocks do I need?
Area ÷ the face of one block, plus cutting waste. Blocks are laid tight together, so a 200 × 100 block covers 0.02 m² - 50 a square metre. A 10 m × 5 m drive at 5% for cuts takes 2,625 blocks.
How much sharp sand goes under block paving?
Area × the laying course depth × the sand’s density. At 40 mm and 1.6 t/m³ the same 50 m² drive takes 3.2 t - four 0.85 t bulk bags. The block maker’s guide gives the depth for their block.
How much Type 1 does a block paved drive need?
Area × the compacted depth × 2.1 t/m³, plus 5% waste. At 150 mm that is 16.54 t for 50 m², or 20 bulk bags. The right depth for your ground is a design decision; this works out the quantity.
What is not in the budget line?
Sand, sub base, kerbs and VAT. It prices the blocks per square metre at your price, with the cutting allowance, and laying at your rate per square metre.
Calculators for the same job
Doing this for a whole job rather than one wall? SiteLedger keeps the valuations, supplier statements, invoices and variations against the project they belong to.
Read before you order. These work out quantities, not structural design — spans, lintels, rebar and foundation depths need an engineer and Building Control sign-off. Waste allowances are defaults, not promises: awkward cuts, long runs and bad weather all eat more than 5%. Where a merchant sells whole packs, the figure is rounded up to whole packs.