Resistor Network and Standard Value Calculator

Add resistors in series or parallel, find the nearest standard value (E12, E24 or E96) for a target, or find the best pair of standard resistors, in series or in parallel, that makes a value you cannot buy.

Separate with commas or spaces. Use k and M for kilo and mega: 4.7k, 2M2, 330.
Total resistance
Detail

How it works

In series the resistances add: R = R1 + R2 + … In parallel the conductances add: 1 ÷ R = 1 ÷ R1 + 1 ÷ R2 + …, so the total is always below the smallest resistor; for two resistors R = R1 × R2 ÷ (R1 + R2). Standard values come from the E series (IEC 60063): E12 has 12 values per decade (10 percent parts), E24 has 24 (5 percent) and E96 has 96 (1 percent), spaced so that neighboring values are about the same percentage apart. The pair search tries every combination of two standard values over seven decades, in series and in parallel, and lists the closest. See Resistors for the background.

Worked example

4.7 kΩ in series with 2.2 kΩ is 6.9 kΩ; 1 kΩ in parallel with 2.2 kΩ is 1 × 2.2 ÷ 3.2 = 687.5 Ω. The nearest E24 value to 4.8 kΩ is 4.7 kΩ (−2.1 percent). For a target of 1.55 kΩ, which is not in E24, the search finds 1.5 kΩ + 51 Ω = 1.551 kΩ, within 0.1 percent, so two common parts give a value that you cannot buy as one.

Things to know

The result uses nominal values. With 5 percent resistors the combination can be off by up to 5 percent; use 1 percent parts for precision.

Mixing a large and a small resistor in series or parallel makes the small one dominate (series: the large one; parallel: the small one), so the pair for a trim is typically one big and one small value.

Power divides in series in proportion to resistance and in parallel in inverse proportion: check each resistor’s rating.

For a divider, the ratio matters more than the absolute values: choose both from the same series, and use the ratio search by trying different targets.

Common questions

What are E12, E24 and E96?

Series of preferred values per decade: 12, 24 and 96 values, matching 10 percent, 5 percent and 1 percent tolerance parts. Each value is about 10 to the power 1/N times the one before (for N = 12, 24 or 96) rounded to 2 or 3 digits.

Why is the parallel total always smaller?

Each extra resistor gives the current another path, so the total conductance rises and the total resistance falls below the smallest.

How do I write the values?

Plain numbers (330), k for kilo (4.7k), M for mega (2M2 or 2.2M). The letter can also stand in for the decimal point: 4k7 is 4.7 kΩ.

Can I use this for capacitors?

Capacitors add in parallel and combine like resistors in series (the reverse of resistors); this tool is for resistors only.

Sources

  • IEC 60063, Preferred number series for resistors and capacitors.
  • Horowitz, P. and Hill, W., The Art of Electronics, 3rd ed., Cambridge University Press: resistor combinations and standard values.

Last reviewed: October 22, 2026