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Accurate construction calculators, trusted formulas and practical tools for professionals and DIYers.
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All calculators →Concrete Calculator
How much concrete a rectangular slab or footing needs, in cubic yards or cubic metres.
Cubic Yard Calculator
Convert a length, width and depth into cubic yards, cubic feet or cubic metres.
Roof Area Calculator
Sloped surface area of a simple gable or hip roof from its footprint and pitch.
Sonotube Concrete Calculator
Concrete volume for round column forms (Sonotube-style tubes).
Concrete Calculator for Fence Posts
Concrete volume to set a run of fence posts, allowing for the posts displacing concrete in each hole.
Browse by Category
Category index →All 97 calculators across 19 categories are live — each with its formula, a worked example, its assumptions and its sources.
Featured Guides
View All Guides →How to Calculate Concrete Volume for a Slab
Concrete volume for a slab is length × width × depth, converted to a single unit. Here's the formula, the unit traps, and a worked example.
How Much Concrete Do I Need? Complete Guide
A complete walkthrough for sizing a concrete order — volume, waste allowance, and the difference between the exact figure and what you actually call in.
How to Calculate Roof Area From Roof Dimensions
Roof area isn't the same as the building's footprint — the slope factor from the pitch stretches a flat area into the real sloped surface.
How to Calculate Tile and Flooring Quantity
Tile and flooring quantity starts with room area, then adds a cut-waste allowance that depends heavily on the layout pattern you choose.
Latest Insights
View All Insights →Concrete vs Cement: What's the Difference?
Cement is an ingredient; concrete is the finished product made from it. Mixing up the two terms is one of the most common mistakes in construction conversation.
Understanding Roof Pitch: 4/12, 6/12 and Other Ratios
Roof pitch notation like 6/12 tells you the rise over a 12-unit run — here's how to read it and what different ratios mean for a roof in practice.
Gravel Sizes Explained: Which Size Do You Need?
Gravel comes in a range of standard sizes, each suited to a different job — drainage stone, base material, and decorative surface stone all differ.
What Is Aggregate and Why Does Gradation Matter?
Aggregate is the sand and crushed stone in concrete, asphalt and base layers — and its gradation (the mix of particle sizes) matters as much as its size.
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Missing a tool you need on the job? On the contact page, pick “Request a calculator” as the topic and describe what it should work out — the form assembles your request and copies it to your clipboard to send.
Request it on the contact page →Accuracy & Trust
Every calculator shows its formula, a worked example, its assumptions and its sources. Results are shown exact and waste-adjusted as two separate figures — waste is never applied silently, and you can always change the percentage. Every formula and every constant it uses is traced to a published source — unit conversions to NIST SP 811, building limits to the International Residential Code, structural loads to ASCE 7 — and checked against a worked example.
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