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Free Building Material Calculators (Australia)
Work out exactly how much concrete, bricks, paint, tiles, flooring, insulation or gravel your project needs — and get your stair and fence measurements right — before you order. The free OBI Material Calculators are built for Australian owner builders, using standard Australian product sizes and units. Every calculator includes a recommended wastage allowance and produces a clear quantity summary you can take straight to your supplier — so you order once, order right, and avoid paying for a second delivery. No account needed, works on any device, and your data stays on your device.
Why Use These Calculators
Order once, order right
Under-ordering means a second delivery fee and days lost waiting on materials. Over-ordering means paying for product that ends up in the skip. Accurate quantities upfront protect both your budget and your schedule.
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Built for Australian materials
Every calculator uses standard Australian product sizes, units, and coverage rates — from 230mm bricks to 90mm Besser blocks — so your results match what your supplier actually stocks.
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Walk in with a number, not a guess
Each calculator gives you a clear quantity summary, including a sensible wastage allowance, that you can hand straight to your supplier for a quote. No account, no email, and your figures never leave your device.
Information
These calculators provide estimates based on standard Australian material sizes and typical coverage rates. Actual quantities can vary with site conditions, product selection, installation method, and workmanship. Always confirm final quantities and specifications with your supplier, and where required, your licensed builder, engineer, or building surveyor before ordering. The Owner Builder Institute accepts no responsibility for ordering decisions made using these tools.
Other Free Owner Builder Institute Tools
Plan your build with confidence using our free Owner-Builder Budget Planner, designed specifically for Australian projects.
Compare builder and trade quotes side by side with our free Owner-Builder Quote Comparison Tool.
Frequently Asked Questions
Are these calculators free?
Yes. All ten calculators are completely free, with no account, sign-up or email required. They're part of the free tool suite we provide to Australian owner builders, alongside our Budget Planner, Quote Comparison tool and Construction Diary.
Do the calculators use Australian sizes?
Yes. All calculations are based on standard Australian product dimensions and units — standard 230 × 110 × 76mm bricks, common Besser block sizes, batt coverage per pack, and material quantities in the metric units Australian suppliers quote in.
How much wastage should I allow?
It depends on the material and the job. Each calculator includes a recommended wastage allowance as a starting point — typically 5–10% for most materials, and more for tiles laid diagonally or cuts around complex shapes. You can adjust the allowance to suit your project.
Can I rely on these numbers to place an order?
Treat them as a strong starting estimate. Actual quantities vary with site conditions, product selection and installation method, so always confirm final quantities with your supplier — and for structural work like footings, slabs and stairs, with your engineer or licensed builder.
Will you be adding more calculators?
Yes. The calculator range is growing based on what owner builders tell us they need. Decking, retaining wall and paving calculators are on the way.
Planning an Owner Builder Project?
Accurate material quantities are just one part of running a successful build. Our owner builder courses take you through the whole process — budgeting, permits, managing trades, staying safe on site and avoiding the mistakes that cost first-time builders thousands.