MeasureHaven

Concrete

Post-hole concrete calculator

Estimate concrete around round posts in round holes, including post displacement and bag count.

Your project

in
ft
in
ft³
%
Extra material for cuts, spillage or irregular edges. Adjust for your project.
Optional. Enter your supplier’s price; 0 leaves cost out.

YOUR ESTIMATE

Enter your measurements and select Calculate estimate.

Planning estimate only. Confirm the product’s coverage and your measurements before ordering.

How to use this estimate

Enter only the depth occupied by concrete, not a gravel drainage layer below it. This model subtracts a round post that passes through the entire fill depth. It assumes a vertical cylindrical hole; flared, tapered or irregular excavations need separate measurements.

The calculation

Net volume = π × (hole diameter² − post diameter²) ÷ 4 × fill depth × hole count.

A worked example

Six holes, each 12 in across and filled 2 ft deep around 4 in round posts, need 8.3776 ft³ before allowance. At 10% extra and 0.6 ft³ per bag, buy 16 bags.

Round posts only. The tool does not determine post embedment or footing diameter for wind, fence height or local conditions.

Common questions

What about square timber posts?

This model is for round posts. Do not substitute a square post width as a diameter; the displaced volume differs. A square-post mode is a future extension.

References & method

QUIKRETE concrete mix product data. See how we check calculations. Reference links provide context; no supplier endorses this site.