Maker tools

Small calculators for the questions that come up mid-build. Nothing to download, nothing to sign up for — open one on your phone at the bench and use it.

• Resistor colour codeRead a resistor's value straight off its coloured bands. 4-band and 5-band.
• LED resistor calculatorSupply voltage and LED forward voltage in, the resistor you need to buy out.
• Wire gauge & voltage dropCurrent and run length in, a safe AWG size and the voltage you'll lose over the run.
• 3D print cost estimatorFilament weight, print time and your rates in, a price to charge or budget out.
• Unit converterLength, weight, volume and temperature — metric and imperial, either direction.
• Ohm's law calculatorVoltage, current, resistance, power — fill in any two, get the other two.