Retaining Wall – Height, Base & Drainage

This tool applies the formula Base Width = 0.5 × Wall Height (gravity); H ÷ 2 embed for toe; Drain m³ = Length × 0.3 × 0.3 directly to the measurements you enter, so the result is an exact quantity rather than a rough guess. Because retaining wall is priced and delivered per unit - cubic meters, square meters, bags or tonnes - a small measurement error multiplies across the entire order, which is why the calculation is worth doing properly. Worked example: A 1.2 m wall, 10 m long: base 60 cm, 24 blocks of 50 × 50 per course, 0.9 m³ drainage gravel. One note from practice: Water is what fells retaining walls - drainage aggregate costs 5% and saves the wall. Enter the wall height, length and soil type, check the totals, then round up to the nearest whole bag, sheet or roll before you place the order.

1. 1

   Take dimensions

   Note the wall height, length and soil type for the area you are covering or filling.

2. 2

   Run the calculation

   The calculator applies Base Width = 0.5 × Wall Height (gravity); H ÷ 2 embed for toe; Drain m³ = Length × 0.3 × 0.3 the moment you type.

3. 3

   Check the breakdown

   Compare base quantity and waste-adjusted totals side by side.

4. 4

   Plan the purchase

   Use the final figure to price and schedule the delivery.

• Forgetting hardware and fasteners

• Unequal riser heights

• Building without permits