Electronics Calculators & Reference Charts
Free tools for the calculations that come up while you build: working out a resistor from its colors, and choosing the right resistor for an LED. Plus the reference charts people keep open next to the bench.
Calculators
Resistor Color Code Calculator
Pick the bands on a 4- or 5-band resistor to get its value and tolerance, with a full color chart and the common values found in kits.
Open the calculator →LED Resistor Calculator
Enter your supply voltage and LED to get the resistor value, the nearest standard part and the wattage rating to use.
Open the calculator →Reference charts
Soldering temperature chart
Iron settings by solder type and job, with melting points.
View the chart →Solder wire gauge chart
Solder diameters in mm, inches and AWG, and which to use.
View the chart →Schematic symbol chart
Common symbols, designators and value shorthand like 4k7.
View the chart →