Resistor Picker is the best way to decipher the resistor color code and since it's on your Apple Watch, it's always with you.

The app has two modes: the default Select Mode and Standard Value Mode.

In Select Mode, use the up/down arrow keys to enter a resistor value either by number or color. If you enter a standard value, the top line displays in green text.

Use Force Touch to switch to Standard Value Mode and the nearest standard value will be automatically selected. Use the left/right arrows to cycle through all available standard values and the up/down keys to move by factors of ten.

The app implements standard resistor values based on the Electronic Industry Association (EIA) E12 series.