Free tool
Standard Resistor Combination Finder
Enter a target value and search standard E-series resistors for the best single, series, and parallel matches. Compare real component values and error at a glance.
Best match
Top combinations
| Rank | Type | R1 | R2 | Equivalent | Difference | Error |
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How to use
Turn a calculated value into real components
A circuit calculation may produce a resistance that is not sold as a standard part. This tool finds the nearest preferred values and checks whether a more accurate value can be built with two resistors.
Click any candidate value to open the resistor color code calculator with that value preloaded, so you can check the physical color bands in one click.
- Enter your targetType the resistance you need, such as 5kΩ or 4k7.
- Choose an E-seriesMatch the resistors you stock or the precision you require.
- Compare matchesBalance component count, availability, and nominal error.
What are E-series values?
E-series are preferred number sets defined by IEC 60063 for resistors and other electronic components. E12 contains 12 values per decade, E24 contains 24, and E96 contains 96. A larger series offers finer steps and makes it easier to find a close single-resistor match.
Series and parallel formulas
Req = R1 + R2
Parallel connectionReq = (R1 × R2) ÷ (R1 + R2)
The displayed error compares the nominal equivalent resistance with your target. It does not include component tolerance, temperature coefficient, or aging. Check the resistor datasheet when designing precision circuits.
Frequently asked questions
What is the E24 resistor series?
E24 is a preferred-value series containing 24 resistor values per decade. It is commonly associated with 5% tolerance resistors.
How do resistors add in series?
Series resistance is the sum of the individual values. A 2.2kΩ resistor and a 2.7kΩ resistor in series produce 4.9kΩ.
How do resistors combine in parallel?
The equivalent is smaller than the lowest branch resistance. Two equal 10kΩ resistors in parallel produce 5kΩ.
Does the displayed error include resistor tolerance?
No. It compares nominal resistance with the target. It does not include the manufacturing tolerance of each resistor.