Brick & Block Calculator
Free brick calculator. Calculate bricks or blocks needed for any wall. Subtract doors and windows, includes mortar volume and cost estimate.
👆Select a brick size and enter wall dimensions to calculate how many you need
How to Use the Brick & Block Calculator
Enter the wall length and height in metres or feet and inches. Select the brick or block size that matches your project — the most common choices for UK residential work are the Standard UK brick at 215 × 65 mm and the Standard concrete block at 440 × 215 mm. Use the Single or Double skin toggle to specify whether the wall is one layer thick or a double-skin cavity wall. Add up to five door and window openings — each is subtracted from the gross wall area before calculating units. The mortar volume shown is for joints only. Enter a price per unit to see the estimated material cost.
About This Tool
A comprehensive brick and block calculator for builders, bricklayers, and DIY enthusiasts. Supports 7 preset brick and block sizes (UK standard, UK metric, US modular, US jumbo, and three concrete block sizes) plus fully custom dimensions. Calculates units per square metre based on face area plus mortar joint thickness, subtracts door and window openings, applies a configurable waste factor, and estimates mortar joint volume with a 15% mixing wastage allowance. Metric and imperial input modes with live conversion.
The number of bricks per square metre depends on the face size and mortar joint. For a standard UK brick (215 × 65 mm) with a 10 mm joint, each brick occupies 225 × 75 mm = 16,875 mm² of wall face, giving approximately 59.3 bricks per m². For a standard concrete block (440 × 215 mm) with 10 mm joints, each block occupies 450 × 225 mm = 101,250 mm², giving approximately 9.9 blocks per m².
A 10% waste factor is standard for straightforward rectangular walls. Increase to 15% for walls with many openings or complex cuts. Running short risks a colour mismatch from a different production batch — always over-order modestly. Pair with the Concrete Calculator for foundation volumes or the Percentage Calculator for proportion checks.
Quick Reference Table
| Brick / Block | Face (mm) | Units per m² | Typical Use |
|---|---|---|---|
| Standard UK | 215 × 65 | ~59 | Houses, garden walls |
| Metric UK | 225 × 75 | ~53 | Metric coordination |
| Standard US | 194 × 57 | ~73 | US residential |
| Jumbo US | 194 × 70 | ~64 | US queen size |
| Block (standard) | 440 × 215 | ~10 | Internal walls, backing |
| Block (medium) | 440 × 215 | ~10 | External, 140mm thick |
| Block (large) | 440 × 215 | ~10 | Solid dense, 215mm |
Frequently Asked Questions
How many bricks do I need per square metre?
For a standard UK brick (215 × 65 mm) with a 10 mm mortar joint, you need approximately 59 bricks per square metre of single-skin wall. For a standard concrete block (440 × 215 mm), you need approximately 10 blocks per square metre. The exact figure depends on the brick size and joint thickness — this calculator uses your selected brick dimensions to compute the precise number.
What is the difference between single skin and double skin?
A single-skin wall is one brick or block thick and is used for garden walls, internal partitions, and boundary walls. A double-skin wall is two layers thick — used for external cavity walls in houses, where the two skins are separated by an insulated cavity. The calculator doubles the unit count for a double-skin specification.
How do I calculate bricks for a wall with a door and window?
Use the openings section. Click ‘+ Add opening’, enter the door or window width and height, and the area is automatically subtracted from the gross wall area. The calculator then computes units and mortar for the net area only. Add up to five openings for complex walls.
Why is the mortar volume in litres, not bags?
Mortar volume varies depending on whether you use factory-mixed dry mortar in bags, mix on-site from cement and sand, or use a pre-mixed tub. A standard 25 kg bag of dry mortar mix yields approximately 12–14 litres of mixed mortar. Divide the litres shown by 13 as a rough guide to bags needed, then round up and add 10% for mixing losses.
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