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Canadian deck footings

Deck Footing Concrete Calculator

Work out concrete for Sonotube piers and any wider bases in your deck footing plan. The result is in litres and cubic metres, with a bag estimate based on your mix label.

By Berjin B V

Published Updated

Footing detail

Use finished concrete dimensions in millimetres. Enter a Sonotube's inside diameter, not its outside diameter.

Post base over a filled SonotubeThe filled tube is a cylinder; a wider base is an additional volume beneath it.Pier inside diameter (mm)Filled pier height (mm)
The filled tube is a cylinder; a wider base is an additional volume beneath it.
Another footing size
Concrete price example

Optional postal code and province check your location. The price range uses published Canadian retail examples; quantities stay the same.

Concrete and bag estimate

The project bag number assumes leftover mixed concrete is usable across footings. Separate pours may need more whole bags.

How to calculate concrete for deck footings and Sonotubes

Use the inside diameter and filled height of each Sonotube shown on your deck plan. Calculate the concrete in the tube, then add a wider base separately if one is specified. Multiply by the number of identical footings and combine a second size when needed. The result shows litres and cubic metres; the bag count uses your chosen premix yield after adding your allowance.

The formulas behind the estimate

Round pier
π × (diameter ÷ 2)² × filled height
Round base
π × (base diameter ÷ 2)² × thickness
Square base
base width² × thickness
Project volume
sum of [(pier + base) × count] for each group
Project bags
round up [(project volume × (1 + extra % ÷ 100)) ÷ yield per bag]

With millimetre inputs: 1,000,000 mm³ = 1 L and 1,000 L = 1 m³. Base volume is zero for a straight pier. Use the same volume unit for the project and bag yield.

For posts embedded inside concrete-filled holes, use ourfence post concrete calculator.

Measuring Sonotube concrete

Read the tube's inside diameter and the height actually filled with concrete. Add a wider round or square base only when your footing detail calls for one. The post supported on hardware above the pier is not subtracted from the concrete volume.

Where to measure the footing

Side and top views of a concrete pier on a wider base, with four numbered measurements.
  1. Inside diameter of the pier
  2. Filled height of the pier
  3. Width or diameter of the base
  4. Thickness of the base

The side view is on the left and the top view is on the right. Measure pier height from the top of the base so its thickness is counted once. The post sits above the concrete.

Example: six tube piers

Six 300 mm diameter tubes filled 1,200 mm high contain about 509 L. Add 5% and the order becomes about 534 L (0.534 m³). With a verified 14 L yield per bag, that is 39 whole bags for a shared pour.

Read the tube and base as two shapes

A Sonotube size describes the form, but the inside diameter defines the concrete volume. If your permit drawing has a wider base, measure its depth below the tube separately. Some drawings show a belled or tapered base; this calculator models only a flat round or square base of uniform thickness. The height above finished grade is still concrete and belongs in the filled tube height. Keep the post and its bracket out of the pier measurement when the bracket sits on top.

Compare bags with a delivery

The bag estimate uses your product’s yield in litres, not just the weight printed on the front. The result rounds the shared project total once, which can be lower than buying whole bags for each pier separately. If you intend separate pours, look at bags per footing too. The cubic-metre result helps when asking a supplier about ready-mix; confirm the order minimum, access and mix specified on your plan before choosing between delivery and bags.

Using your postal code for a bag cost guide

The postal code helps locate a province or a covered metro area. The guide then prices a separate reference count of 30 kg concrete mix bags at about 14 L each, using published retail examples. The postal code checks the province; it does not change these published Canadian price examples. This is not a store-specific price or an estimate of frost-depth work.

If your chosen bag has a different yield, use the calculator's main bag count and enter that product's price per bag for a better material estimate. Confirm stock, tax, delivery and any minimum order with a nearby supplier. Neither the postal code nor the price changes the footing dimensions on your permit plan.

Retail examples (30 Sep 2026): Home Depot Canada.

Canadian planning checks

Frost depth, soil bearing and tributary loads can change the footing size. Obtain the dimensions from your permit drawing or local authority. Compare the bag count with a ready-mix delivery and verify the exact yield and suitability of the product.

Common questions

Do I use the Sonotube's nominal outside size?

Use its inside diameter, because that defines the concrete cylinder.

Does this size the footing for frost?

No. It estimates concrete for dimensions already selected on your deck plan. Verify depth and bearing requirements locally.