Free in-browser concrete calculators for slabs, columns and post holes. Volume in cubic yards, cubic feet or cubic metres, with a 10% waste buffer.
Calculate the concrete volume for a rectangular slab from length, width and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Open calculator →Calculate the concrete volume for a circular slab from diameter and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Open calculator →Calculate the concrete volume for an irregular slab from a pre-measured area and depth. Imperial and metric units, with a 10% waste buffer per ACI 318.
Open calculator →Calculate the concrete volume for a circular column from diameter and height. Imperial and metric units, with a 10% waste buffer per ACI 318.
Open calculator →Calculate the concrete volume for fence-post holes — by hole, total across all holes, with post-profile displacement and a 10% waste buffer.
Open calculator →The same calculators, set up for a specific job — with the sizing rules, thickness guidance and bag counts that go with it.
Work out how much concrete fills a Sonotube or round column form. Standard tube sizes, concrete per foot, bag counts and a 10% waste buffer.
Open calculator →Work out how much concrete each fence post needs, and the total for the run. Hole sizing rules, bag counts per post and a 10% waste buffer.
Open calculator →Work out how much concrete a driveway needs from its length, width and thickness. Common driveway sizes, thickness guidance and a 10% waste buffer.
Open calculator →Web-only tools for the arithmetic around a pour — turning volumes into yards, bags or a budget.
Work out cubic yards from length, width and depth. Results in cubic yards, feet and metres, with a 10% waste buffer for ordering.
Open tool →Convert cubic feet to cubic yards and back. Divide by 27 — with a conversion table, worked examples and what it means for ordering.
Open tool →Work out how many bags of concrete a pour takes. Covers 40, 50, 60 and 80 lb bags plus 20, 25 and 30 kg, with bags-per-yard tables.
Open tool →Estimate what a concrete pour will cost from your supplier's quoted rate, including the waste buffer and delivery or short-load fees.
Open tool →Work out how much rebar a slab needs from its size and bar spacing. Bar counts each way, total length, weight and stock lengths.
Open tool →Work out what concrete weighs from its volume. A cubic yard is about 4,050 lb and a cubic metre about 2.4 tonnes, with lightweight mixes covered.
Open tool →The Concrete Calculator app for iOS has every calculator above plus saved projects, full offline support, and history across all your jobs.
