Resistor E-Series Lookup

Summary

Enter a target resistance and pick an E-series to find the nearest standard resistor value with its percent difference.

How it works

1. Enter the target resistance value you calculated (for example from a voltage divider or LED resistor formula).
2. Choose the unit: ohms, kilohms, or megohms.
3. Select the E-series that matches the tolerance you need (E6 = 20%, E12 = 10%, E24 = 5%, E48 = 2%, E96 = 1%).
4. The tool scales your target into the 1-to-10 decade, scans the series values around it, and ranks them by percent difference.
5. The closest match is highlighted; the next-lower and next-higher standard values are shown for reference.

Use cases

• Round a calculated voltage-divider resistor to a value you can actually buy.
• Check how much error a substituted resistor value introduces into a design.
• Pick a tighter-tolerance series (E96) when a design needs more precision.
• Verify that a resistor value printed on a datasheet BOM is a real standard value.
• Compare E24 versus E96 options when sourcing parts for a production run.
• Teach or learn the IEC 60063 preferred number system used for resistors and capacitors.

Frequently Asked Questions