Concrete Footing Calculator

Measure the dimensions your plans or project already specify — a continuous footing's total run length, width, and depth; an isolated footing's length/width or diameter, and its depth. This calculator does not tell you what those numbers should be; it converts the numbers you already have into concrete volume.

A continuous (strip) footing runs along the full length of a wall or similar continuous line — a foundation wall, a fence line. A rectangular isolated footing (also called a pad footing) supports a single point load, like a post or column base. A round footing covers a round or pier-shaped footing — common under a deck post or a Sonotube-formed pour. All three are common, and a real project often combines more than one type.

A continuous footing's “total length” is the entire run — not a single segment repeated. That's why this footing type has no quantity field: the length you enter already covers the whole footing, so a multiplier would double-count it.

Add one section per footing type or run in your project — a strip footing, several pad footings, a handful of round footings. Each section's volume is calculated in full, all sections are added together at full precision, and only then is the order allowance applied once to the combined total. Nothing is rounded section-by-section along the way.

Field dimensions rarely match plan dimensions exactly. NRMCA's own technical guidance (CIP 8, “Discrepancies in Yield”) recommends ordering roughly 4-10% over the calculated volume for waste, over-excavation, and placement contingencies — explicitly as a range, not one fixed number. This calculator's 5% default sits in that range but is fully editable.

CIP 8 specifically notes that sporadic, combination work — footings, walls, and incidental fill together — tends to need a bigger allowance than a single controlled, repetitive pour. A hand- or machine-dug footing trench in undisturbed soil often has more over-dig variance than a screeded slab subgrade, so many footing projects sit toward the higher end of the 4-10% range rather than the low end. There is no single correct number for every project — adjust the allowance for your own site conditions.

Ready-mix concrete is delivered by truck in bulk and suits larger pours where the volume justifies a delivery. Bagged concrete mix is measured and mixed on site bag by bag, and suits smaller footing projects, repairs, or a handful of isolated footings where a full truck delivery isn't practical. Bag counts use your product's manufacturer-stated mixed yield, never a figure guessed from bag weight — two bags of the same weight from different manufacturers do not necessarily yield the same mixed volume.

Truck capacity is not standardized — it varies by supplier, region, and truck, so this calculator never assumes a figure. Enter the usable capacity your supplier quotes to see how many truck-capacity equivalents your order needs and how many whole truckloads to plan for. This is planning-only: it does not determine supplier minimum orders, short-load charges, or delivery policies.

Use this calculator when your project is footings only — it uses footing-specific terminology and diagrams, and combines continuous, rectangular, and round footings into one order.

Use the Concrete Calculator when you're combining footings with columns, piers, walls, or other non-footing shapes in one project. Use the Concrete Slab Calculator when you're pouring flatwork instead of a footing.

• Recommended footing width or depth.
• Bearing capacity or soil-bearing calculations.
• Frost-depth requirements.
• Reinforcement or rebar sizing.
• Structural loads or foundation engineering.
• Building code or local requirement compliance.

This calculator takes dimensions you already have — from your drawings, your plans, or a professional — and converts them into concrete volume. Those design decisions belong to your project documents or a qualified professional.