Garden Wall Calculator — Bricks, Mortar & Foundations

Our garden wall calculator works out the total number of bricks needed for the wall face, piers, mortar quantities, coping stones and foundation concrete.

The formulas

Wall bricks = Wall area (m²) × Bricks per m²

Pier bricks = Number of piers × 4 bricks/course × Courses (a conservative allowance — a bonded-in pier reuses some wall bricks, so this slightly over-orders to cover the bond and cutting waste)

Courses = Wall height ÷ 0.075m (65mm brick + 10mm joint)

Foundation volume = Length × 0.45m wide × 0.225m deep

Brick quantities per m²

• Half brick wall (102.5mm): 60 bricks per m²
• Full brick wall (215mm): 120 bricks per m²

Mortar (1:6 mix)

• Half-brick wall: ≈6 kg cement + ≈40 kg building sand per m²
• Full-brick wall: double that (≈12 kg cement + ≈80 kg sand per m²)

Based on ≈0.03 m³ of dry mortar per m² of half-brick brickwork at 1:6 by volume, including an allowance for bulking and wastage.

Good-practice guide values

• Half-brick freestanding wall: piers needed above ≈450mm (wind-zone dependent, ≈375mm exposed to ≈525mm sheltered)
• Pier spacing: 3m centres maximum
• Foundation: 450mm wide × 225mm deep minimum for walls up to 1m
• Mortar mix: 1:6 (cement:sand) for sheltered positions, 1:4 for exposed / below DPC

These figures follow BRE Good Building Guide 14 and Brick Development Association / PD 6697 good practice for freestanding garden walls in the UK (the structural masonry code is now BS EN 1996, Eurocode 6, which replaced the withdrawn BS 5628). For retaining walls, structural engineering advice is required.