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Concrete Footing Calculator

Calculate concrete for foundation footings, deck post footings, fence post footings, and structural footings. Cubic yards, bag count, rebar calculation, and cost.

You'll need
0.81 cu yd · 37 bags
Cost
$222$370
Project details
What are you pouring?
Footing dimensions
gradeLength (L)Width (W)D
Quantity

e.g. 8 fence post holes, 3 footings

How you'll buy it

Leave blank to use estimate

Default estimate: $130–$180/yd. Most suppliers have a 1–3 yard minimum.

Reinforcement & site prep
Labor

Cost breakdown

Showing bag pricing (80 lb bags).
80 lb bags · 37 bags$222 – $370
Total project cost$222 – $370
💡 Comparison: 37 80-lb bags would cost $222$370; ready-mix (1.00 yd) would cost $130$180.

Shopping list

Everything you need for this pour.
  • 80 lb concrete mix bags37
  • Concrete mixing tub or wheelbarrow1
  • Mason hoe or mixing tool1
  • Gloves, eye protection, knee pads1 set
Ready to pour?
Pick up Quikrete or Sakrete bags at Home Depot.
Shop now →

Math breakdown

Step-by-step from your inputs.
Footing volume · 20 × 1 × 120.00 cu ft each
With 10% waste factor22.00 cu ft
Cubic yards · cu ft ÷ 270.81 cu yd
Estimated weight (wet)3,190 lbs
80 lb bags · ÷ 0.6 cu ft per bag37 bags

Pro tips

Dig below frost line. Footings must extend below your local frost depth, which varies from 12 inches (Florida) to 60+ inches (northern states). Check your local code. Frost heave cracks footings poured too shallow.

Always rebar footings. Use 2 #4 (1/2 inch) rebar bars running continuously through the footing, with stirrups every 18 inches. Non-negotiable for structural footings.

Footings are wider than what they support. Footing width = 2× wall thickness as a rule of thumb. 8-inch wall → 16-inch wide footing. Spreads the load.

Frequently asked questions

How deep should a footing be?
Below the frost line in your area (12-60 inches), AND at least 12 inches into undisturbed soil. Verify with your local building department.
Footing for a 6×6 deck post?
Typically 12-inch diameter × frost-line depth (often 36-48 inches). For a 4-foot deep frost-line footing: π × 0.5² × 4 = 3.14 cubic feet (about 5 × 80 lb bags).
Can I pour a footing without rebar?
Non-structural fence post footings: yes, plain concrete is fine. Deck and structural footings: always rebar. Don't risk it.
Footing or pier — what's the difference?
Footings are wider than the wall/post they support (load-spreading). Piers are vertical columns above the footing (load-transferring). A typical deck post has both: a footing at the bottom, a pier rising up to the post.

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Disclaimer. This calculator provides estimates for planning purposes. Actual material quantities and costs may vary based on site conditions, material availability, and local pricing.