Concrete calculator

Convert thickness before calculating volume

Length and width are entered in feet, while thickness is entered in inches. Dividing thickness by 12 converts it to feet. Multiplying all three dimensions gives volume in cubic feet; dividing by 27 converts cubic feet to cubic yards.

Waste and whole bags are separate steps

The waste allowance is applied to the geometric volume for spillage, uneven excavation, form variation, and handling losses. The adjusted cubic feet are then divided by the stated yield per bag and rounded upward because partial unopened bags cannot be purchased.

Measure the actual shape

This version models one rectangular prism. Divide steps, footings, pads, or irregular work into non-overlapping simple sections and add their volumes. Never use the calculator to choose structural dimensions, reinforcement, mix design, cure procedure, or load capacity.

Bag yield must match the product

Dry bag weight does not directly equal finished concrete volume. Use the yield printed for the exact mix and bag size. Moisture, compaction, subgrade movement, excavation tolerance, and site conditions can change actual demand. Ready-mix orders may use supplier minimums and a different reserve convention.

This is a volume and purchase-planning estimate, not structural, construction, engineering, or safety advice. Confirm dimensions, required thickness, product yield, local requirements, and supplier guidance before ordering or pouring.