Fencing · Project planning

Fence Post Concrete Calculator

Subtract the embedded post from a round hole and deduct gravel and top backfill before converting concrete volume into whole bags.

By Alish Gautam, Software Developer · Updated · Calculation methodology

Start with the editable example below. Dimensions retain their physical size when units change. Region sets currency labels without converting currencies; confirm entered quotes after changing region.

Basic settings
Editable arithmetic example. Replace with your project or product specification.
Editable arithmetic example. Replace with your project or product specification.
Editable arithmetic example. Replace with your project or product specification.
Product settings
Product and system dimensions
Editable arithmetic example. Replace with your project or product specification.
Choose none to omit displacement.
Editable arithmetic example. Replace with your project or product specification.
Editable arithmetic example. Replace with your project or product specification.
QUIKRETE Concrete Mix No. 1101: 80 lb ≈ 0.60 ft³; 60 lb ≈ 0.45 ft³. Select custom for another bag or product.
Optional supplier product name, chart revision or quote reference, saved in shared project state.
Advanced settings
Advanced planning settings
Planning allowance, not a code or industry requirement. Set zero to order the exact rounded takeoff.
Cost settings · USD
Optional quote prices
Optional supplier quote in the selected currency. Blank omits cost.

Project takeoff

Whole packages round up. Allowance is separate from purchased surplus. Prices omit labor, delivery, tax and other items unless explicitly entered.

Concrete fill depth
24 in
Concrete per post
1.401 ft³
Net requirement
14.007 ft³
Allowance
1.401 ft³
Planned requirement
15.407 ft³
Unrounded package requirement
25.679
Concrete bags
26
Purchased coverage
15.6 ft³
Surplus beyond planned requirement
0.193 ft³

Supplier-ready material list

Concrete bags
26

Bag yield is product-specific. The displayed 0.60 ft³ example is QUIKRETE Concrete Mix No. 1101, 80 lb; custom yield overrides it. Excavation and mixing losses need a separate allowance.

How it works

Concrete = [π × (hole diameter / 2)² − post cross-sectional area] × fill depth × posts. Fill depth = hole depth − gravel − backfill.

Assumptions and limitations

Bag yield is product-specific. The displayed 0.60 ft³ example is QUIKRETE Concrete Mix No. 1101, 80 lb; custom yield overrides it. Excavation and mixing losses need a separate allowance.

Whole packages round upward after the chosen allowance. Physical geometry and purchase reserve are separate. Manufacturer and project specifications override editable examples; the selected region does not establish a local code requirement.

Sources and boundaries

QUIKRETE: Concrete Mix No. 1101 — SPEC-DATA

Open the source · No. 1101 SPEC-DATA · Reference checked 2026-10-04

Scope: Yield of the specified packaged mix

Used for: 80 lb approximate yield 0.60 ft³; 60 lb approximate yield 0.45 ft³.

Does not establish: All concrete products; Fast-setting mix equivalence.

Only verified 60/80 lb presets are offered; custom bag yield remains available.

QUIKRETE: Setting Posts without Mixing

Open the source · Web guidance; edition not stated · Reference checked 2026-10-04

Scope: Manufacturer general post-setting instructions

Used for: One-third to one-half above-ground-height planning reference.

Does not establish: Local frost depth; Wind design; Universal minimum embedment.

Planning guidance must be checked against soil, loads and project requirements.