Concrete Calculator

Add one section for each different pour in your job, choose its shape, enter the dimensions you already have, and set how many identical pours of that shape you need. A deck might be eight piers plus two pads; a foundation might be a run of footings plus several columns. The calculator combines them all into one total and one concrete-to-order figure, so you place a single order instead of adding up separate calculations by hand.

Rectangular covers anything box-shaped — a wall, a strip or pad footing, a beam, a curb. Volume is length × width × height (or depth).

Round covers anything cylindrical — a column, a pier, a round footing, a Sonotube-formed pour. You enter the diameter because that's what you can actually measure across a hole or a form; the calculator halves it to get the radius, then uses π × r² × height.

Hollow round covers ring-shaped pours — a circular wall, a tube, a ring beam. It subtracts the empty core: π × (outer radius² − inner radius²) × height. The inner diameter must be smaller than the outer one.

Each section's per-unit volume is multiplied by its quantity, and those section totals are added together at full precision. Only then is the order allowance applied. Nothing is rounded section by section along the way — rounding each piece first and then adding is how estimates drift. Eight piers of 0.0873 yd³ each, for example, total 0.70 yd³, but rounding each to 0.09 yd³ first and summing would wrongly give 0.72 yd³.

Field dimensions rarely match plan dimensions exactly — forms deflect, excavations come out slightly oversize, and some concrete is always lost to spillage. NRMCA's technical guidance (CIP 8, “Discrepancies in Yield”, and CIP 31) recommends ordering roughly 4–10% over the calculated volume for these contingencies, framed as a range rather than a fixed number: controlled, repetitive placements sit at the low end, while irregular or hand-dug work needs more. The 5% default sits in that range and is fully editable — there is no universally correct figure.

Ready-mix arrives by truck and is ordered in cubic yards or cubic meters, which suits larger pours. Bagged concrete is mixed on site and suits smaller jobs — a handful of piers, a small pad, a repair. Neither is universally better; it depends on your volume, site access and your supplier's minimum order.

If you enter a bag yield, the bag count divides your order volume by the manufacturer's stated mixed yield — the volume one bag makes once water is added — never by the bag's dry weight. Two bags of the same weight from different manufacturers don't necessarily yield the same volume, so check your own product's data sheet.

Use this calculator when your job has more than one shape, or repeated objects you want to multiply — footings, columns, piers, walls, rings. Its job is combining different pours into a single order.

Use the Concrete Slab Calculator when you're pouring flatwork. It's built around slab thinking — area and thickness — and adds slab-specific planning this page deliberately leaves out: truckload planning and a ready-mix-versus-bagged cost comparison.

Footings only? Use the dedicated Concrete Footing Calculator for footing-specific terminology, diagrams, and material planning.

Building solid concrete steps? Use the dedicated Concrete Stairs Calculator for stair-specific geometry and material planning.

A round section calculates the full volume of the hole or form. If a post occupies part of that space, this calculator does not subtract its volume, so the result may be higher than the concrete actually placed. For post-setting jobs where displacement matters, use a dedicated post-hole calculation rather than treating this result as an exact concrete requirement.

Everything here is quantity estimating. The calculator takes dimensions you already have — from your drawings, your plans, or a professional — and converts them into concrete volume. It does not tell you how big a footing should be, how deep to go below frost, what a column needs to carry a load, what concrete strength to specify, or what reinforcement is required. Those are design decisions that belong to your project documents or a qualified professional.