A simplified approach for complex calculations

Calculating an electrical resistance can be a challenging task. ResCalc does the heavy lifting for you — a clean, organized interface so you can focus on the things that really matter.

→ Open the Web App

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Inside the app

More than a calculator.

ResCalc Coil Locker — saved coil builds — **Coil Locker.** Save every build and revisit it whenever you need it.

ResCalc — adding core wires in the calculator — **The calculator.** Add your core wires — accurate results from minimal input.

ResCalc Showroom — community build specs — **Showroom.** Share builds and specs with the community.

What it does

Built for people who wind their own.

Five years of refinement, driven by real community feedback. Precise where it counts, quiet everywhere else.

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Every wire, every shape

Round, ribbon and square wire. Single, parallel and twisted builds — ResCalc handles the geometry.

Resistance & power density

Not just ohms. Surface area and power density, so you understand how a coil actually behaves.

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AWG & metric

Work in wire gauge or millimetres. ResCalc speaks both and converts on the fly.

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Fast & clean

A focused, organized interface. Enter what you know, read what you need — nothing in the way.

● Materials NiCr80 NiCr90 SS304 SS316 Kanthal A1

The story

Shipped in 2020. Still maintained.

ResCalc launched on the Apple App Store in December 2020 — a comprehensive calculator built specifically for the electrical resistance of heating coils. The goal was a user-friendly interface that delivers accurate results from minimal input, distilling a complex calculation down to what actually matters.

The response brought a wave of requests for Android, so a counterpart was built from the ground up in React Native — version 1.6 reached the Play Store about a year later. The native Android app has since been retired, but the Web app runs anywhere a browser does, Android included.

ResCalc V2 grew it into more than a calculator: a community Showroom where people share their coil builds and inspire each other. Five years on, it is still maintained on iOS and ★★★★★ rated.

Get started

Calculate your next build.

Free on the App Store, or run it right now in your browser — no install.

→ Open the Web App