About Concrete Calculator

Concrete Calculator is a free, client-side web tool that instantly estimates concrete volume, bag counts, mix ratios, and saw-cut spacing. It runs entirely in your browser — no sign-up, no app to install, and no data is sent to our servers.

Who we are

Concrete Calculator is operated by Nexus Web Tools, an Australian-based digital tools publisher that builds practical, browser-based calculators and utilities for construction, engineering, and finance professionals. Our team has over a decade of combined experience in construction estimating, civil engineering, and web application development. We created Concrete Calculator after repeatedly seeing DIY builders and tradespeople order the wrong amount of concrete — either too little (leaving a half-poured slab) or too much (wasting hundreds of dollars). The tool was designed to be fast, accurate, and easy enough for anyone to use on a phone at the building site.

What we offer

The calculator supports both metric and imperial units and includes:

• Volume estimation for slabs, footings, and round columns — with automatic unit conversion.
• Bag count estimates for 20 kg, 30 kg, 40 kg, 60 lb and 80 lb bags.
• Mix design guidance — cement, sand, and aggregate quantities by strength grade (20–40 MPa).
• Saw-cut (control joint) spacing recommendations based on industry rules of thumb.
• Graded-land mode for calculating concrete volume on uneven or sloping ground using four corner depths.
• Volume subtraction for slabs with cut-outs, footings, or voids.

Our approach to accuracy

All calculations use established engineering formulas and industry-standard mix ratios published by the Cement Concrete & Aggregates Association (CCAA) and the American Concrete Institute (ACI). The waste allowance, bag yield figures, and joint spacing rules reflect real-world supplier data and construction practice — not theoretical assumptions. That said, the tool is an estimator, not a substitute for professional engineering advice. Always confirm structural requirements with a qualified engineer or your concrete supplier.

Part of the Nexus Web Tools family

This tool is part of the Nexus Web Tools family, a collection of free utilities that includes a Compound Interest Calculator, Mortgage Calculator, S-Curve Cash-Flow Model, and Unit Converter. All tools share the same principles: free, fast, privacy-first, and built for real-world use.

Our commitment to users

• Free forever — no paywall, no premium tier, no sign-up required.
• Privacy-first — all calculations run locally in your browser. We do not store your inputs.
• Mobile-friendly — every tool works on a phone, tablet, or desktop.
• Transparent — formulas and reference tables are visible on the page, not hidden behind the calculator.

Have a question or suggestion? Visit our Contact page or email [email protected]. We typically respond within 48 hours.