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Pro²
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Construction calculators for iPhone.

Work out concrete volume, reinforcement quantities and stair dimensions from your measurements. Check diagrams and keep calculations together for your next job.

Download on the App Store

For iPhone · iOS 18 or later

Free to download.

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Pro² Tools screen with construction calculators.
Choose a construction task, enter your measurements and check the result in Pro².

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Calculate here without an account. Explore the full toolkit in Pro² for iPhone.

Find the tool for the job

Start with what you are measuring. Read about the inputs, results and limits of each tool in Pro² for iPhone.

Dimensions that lead to a useful answer.

Start with the measurements, then see the quantities and dimensions they produce.

Concrete slab

One rectangular slab with a chosen allowance.

Length × width × thickness
3 m × 2 m × 0.10 m
Quantity; extra
1; 10 %
Net; extra; required
0.600; 0.060; 0.660 m³
See the full example

Reinforcing bar grid

One slab, one layer. A runs along the length; B across it.

Slab length × width; cover
5 × 3 m; 40 mm
A: diameter; maximum centres
12 mm; 200 mm
B: diameter; maximum centres
16 mm; 250 mm
Installed total; theoretical mass
140.040 m; 166.672 kg
See the full example

Baluster spacing

Between posts, with gaps at both ends.

Run; baluster width; maximum gap
3000 mm; 40 mm; 100 mm
Straight: count; gap; centres
21; 98.182 mm; 138.182 mm
See the full example

Measure. Calculate. Keep the result.

  1. Enter what you measured

    Choose a tool and use metric units or feet and inches. Match each field to the dimension on its diagram.

  2. Review the whole calculation

    Read geometry, quantities and allowances together. Calculate after changing inputs so the result reflects the values you intend to use.

  3. Return when the job changes

    Keep your measurements with the result. Reopen a saved calculation, change the inputs and save the update or a separate version.

Keep it. Share it.

Keep the measurements with a named calculation. Share the calculated result when you need to discuss the job.

Revisit saved work on your iPhone. Keep the original until you choose to update it, or save a separate version.

A few everyday extras.

Convert units and do everyday arithmetic alongside your construction calculations, all on your iPhone.

Units are part of the calculation. Check the unit beside each input and result, especially when moving between millimetres, metres, cubic yards and US tons.

From the example to your own job.

Calculate free here, read the guides, or continue in Pro² for iPhone.

Useful quantities, clear limits.

Pro² helps with geometry, setting out and material estimates. Dimensions, cover, laps, density and allowances still come from the job. Structural design, product instructions and local requirements need their own checks.

Open all calculator guides

Bring Pro² to your next job.

Use your own measurements for stairs, concrete and materials. Keep the calculations together on your iPhone.

For iPhone · iOS 18 or later

View Pro² on the App Store

Free to download.

Scan with your iPhone camera.