The construction and electrical calculator for iPhone. One toolkit for electricians, builders and DIY: a stair designed in 3D, the right cable and breaker, and the materials for the job, with the working shown.
Free to start. Unlock everything with a subscription or once for life.
Stairs, Electrical and Construction sit on one home screen. Pick the job, enter what you measured, and read the answer with the working beside it.
Stairs
Enter the floor to floor rise and the room you have, and Kupfra lays out the stair: number of risers, riser height, tread run, pitch and step length.
Electrical
Size the cable and check the protection, following IEC 60364, BS 7671 for the UK or the NEC for the US.
Construction
Quantities with adhesive, grout, mortar and waste worked out.
Pick a calculator, enter what you measured, and read the result with the working beside it, so you can check it before you order or wire anything.
IEC 60364, BS 7671 or the NEC
Current capacity, cross-section, voltage drop and protection.
Volts and percent along the length of the run.
Fuses and circuit breakers, checked against the cable.
Fault current estimate and breaker trip check.
Earth electrode resistance and checks.
Fill ratio and the smallest diameter that fits.
Cross-section from length, current and voltage drop.
Quick sums between voltage, current, resistance and power.
Metric or imperial
Volume, ready-mix order, cement, sand and gravel.
Tiles and boxes for the pattern, adhesive and grout.
Litres and cans for walls and ceiling.
Boards, studs, track, screws and joint filler.
Bricks or blocks and mortar for a wall.
Thickness for a target U-value.
Packs, area and skirting.
Rise, rafter length, roof area and tiles.
These turns come from the app's own 3D engine. In Kupfra you drag to turn the stair and pinch to zoom.
Drag to turn
Every value is compared with the guidance you choose: DIN 18065, the US IRC or the English Approved Document K. Headroom is checked against the ceiling opening, and each check names the rule it comes from.
Oak, beech, walnut, concrete or steel, with closed or cut stringers or a steel spine, and wood, metal, glass or horizontal rail balustrades.
Stringer marks for each flight, the treads, landings and risers, ready to share as text or PDF. The materials and cost screen adds board areas, volumes and waste, priced with your own unit prices in your currency.
A cover with the 3D render, plan and side elevation, dimensions, cut list, materials and cost, your notes and the client's signature, under your company name, contact details and logo.
Point the camera at the floor and the floor above to measure the rise, or across the opening to measure its length. Devices with LiDAR use scene depth.
Save a stair or a calculation as a project and pick it up later. Projects stay on your device.
Kupfra comes in 45 languages and follows your device. Units are metric or imperial, set once, and the stair guidance and electrical standard are the ones you pick: IEC 60364 or BS 7671 in Europe and the UK, the NEC in the US, copper or aluminum, PVC or XLPE, by installation method.
The results are guidance for planning. Check your local building code before you build, and have electrical work signed off by a qualified electrician. Kupfra does not replace the code, an engineer or an inspector.
The straight stair, the cable size calculator and the concrete and screed calculator, with up to 3 saved projects. The free version shows ads.
Every stair type, every calculator, design options, the materials and cost estimate, client PDFs, PDF and text export, camera measuring and unlimited projects, and no ads.
Unlock with a weekly or monthly subscription, or buy it once for life. The app shows each price in your currency before you buy, and a yearly plan may also be offered in the app. Subscriptions renew until you cancel in your Apple Account settings.
No account, no sign-in. Your projects, prices and logo are stored on your device, and the camera measures on your device and records nothing. The free app uses Google for ads, analytics and crash reports, and RevenueCat for purchases, as the policy sets out.
Yes to start. The straight stair, the cable size calculator and the concrete and screed calculator are free, with up to 3 saved projects, and the free version shows ads. The unlock adds every stair type, every calculator, design options, the materials and cost estimate, client PDFs, PDF and text export, camera measuring and unlimited projects, and removes the ads.
With a weekly or monthly auto-renewing subscription, or once with a lifetime purchase. The app shows each price in your currency before you buy, and a yearly plan may also be offered in the app.
Electrical results follow IEC 60364, BS 7671 for the UK or the NEC for the US. Stair values are compared with the guidance you choose: DIN 18065, the US IRC or the English Approved Document K. Each result names the table or rule it comes from.
Treat them as guidance for planning. Check your local building code before you build, and have electrical work signed off by a qualified electrician. Kupfra shows its working so you can check it, but it does not replace the code, an engineer or an inspector.
The app tells you as you measure: usually within 2 to 5 cm, and within about 1 cm on devices with LiDAR. Check with a tape before you cut. The camera is used only to measure, on your device. Nothing is recorded or saved.
45 languages, following your device's language. Units are metric or imperial, set once in Settings, and start from your device's region.
iPhone. Camera measuring needs a device that supports ARKit world tracking, and uses LiDAR depth where the device has it.
More help is on the support page.
Free to start on iPhone.
