Preset calculation / editable
How much concrete does a 4 × 4 fence post need?
A nominal 4 × 4 post is 3.5 inches square; subtracting that displacement prevents ordering concrete for space the post occupies.
Calculated result / live
4 80 lb bags
Order 4 80 lb bags; confirm package yield and supplier increments before purchase.
Input panel
Project measurements
Nominal 4 × 4 is 3.5 in actual; nominal 6 × 6 is 5.5 in.
| Cubic feet | 2.311 |
|---|---|
| Cubic yards | 0.09 |
| 80 lb bags | 4 |
| 60 lb bags | 6 |
Calculation trace
Formula with your numbers
π × (12.00 in ÷ 24)² × (36.00 in ÷ 12) − (3.50 in² × 36.00 in ÷ 1728) = 2.101 ft³
Take to supplier
Materials list
- 4 80 lb bags
- 10% waste allowance
- Verify current product yield before ordering
Size-specific decision
A nominal 4 × 4 post is 3.5 inches square; subtracting that displacement prevents ordering concrete for space the post occupies. The default result is present in the static page and remains editable.
Source: QUIKRETE Concrete Mix product data sheet. Product No. 1101, retrieved 2026-09-05.
Open the unrestricted fence post concrete calculator or review the concrete bag yield table.