OctaCalc

Instant, no-nonsense calculators for electronics and electrical engineering. Whether you're sizing a resistor, estimating battery life, or decoding a colour code — OctaCalc gives you the answer without the faff.


Available calculators

resistor colour code calculator illustration

What is OctaCalc?

OctaCalc is a free, browser-based toolkit of practical electronics calculators. Every tool is self-contained — no login, no ads, no fluff. Just enter your values and get a result, whether you're on the bench or on the go.

The calculators cover the most common problems in hobby electronics and electrical engineering: component sizing, circuit analysis, signal timing, power budgeting, and more. New tools are added regularly.

How to use

  1. 1 Pick the calculator you need from the grid below — hover for a short description of what each one does.
  2. 2 Enter your known values. Units are labelled for each field; most calculators handle common prefixes (mA, µF, kΩ, etc.).
  3. 3 Results update instantly — no submit button needed. Note the answer and you're done.

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