Preferred Resistor Value Calculator

Resistors are only manufactured in specific standardized values, so the Preferred Resistor Value Calculator finds the closest available resistor to any resistance you need. Enter your target resistance value, select a resistor series (E12 through E192) and unit (Ω, KΩ, or MΩ) to get the closest single resistor and its error percentage. Enable Show Series/Parallel Combinations to also see the best two-resistor series and parallel pairings for higher precision.

Ω

Target resistance value you want to achieve

Standard resistor series with different tolerances

Calculate series and parallel resistor combinations for better precision

Results

Closest Single Resistor

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Single Resistor Error

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Best Series Combination Value

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Series Combination Error

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Best Parallel Combination Value

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Parallel Combination Error

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Results Table

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Frequently Asked Questions

What are E12, E24, E48, E96, and E192 resistor series?

These are standard resistor value series defined by IEC 60063. E12 has 12 values per decade (10% tolerance), E24 has 24 values (5%), E48 has 48 values (2%), E96 has 96 values (1%), and E192 has 192 values (0.5% or better tolerance).

How do I choose between single resistor and combination options?

Single resistors are simpler and more reliable. Use combinations when you need higher precision than available standard values, or when you need higher power ratings by using multiple resistors.

What's the difference between series and parallel resistor combinations?

Series resistors add their values (R1 + R2), while parallel resistors follow the formula (R1 × R2)/(R1 + R2). Series combinations give higher values, parallel combinations give lower values.

Which resistor series should I use for my project?

Use E12 for general purpose circuits where 10% tolerance is acceptable. E24 is common for 5% applications. E96 is used for precision circuits requiring 1% tolerance. Higher series offer more precise values but cost more.

Why might I need a non-standard resistor value?

Active filters, precision voltage dividers, and impedance matching circuits often require specific resistance values that don't match standard series. Combining standard resistors can achieve these precise values.

How accurate are resistor combinations compared to single resistors?

Combinations can be more accurate in terms of nominal value, but tolerance stack-up means the actual tolerance may be wider. Single precision resistors are often better for critical applications.