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Parallel resistors.

Find the equivalent resistance of two or three parallel branches.

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01 / QUESTION

Two 100 Ω resistors in parallel equal:

R = 1 ÷ (1/100 + 1/100) = 50 Ω.

01 /

How the calculation works

1 / Req = 1 / R1 + 1 / R2 + 1 / R3. Leave R3 blank for two branches.

KEY FORMULA1 / Req = 1 / R1 + 1 / R2 + 1 / R3. Leave R3 blank for two branches.
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Worked example

A 100 Ω and 220 Ω resistor in parallel produce 68.75 Ω.

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Before you rely on this result

Do not enter zero-ohm branches in this calculation. Real-world tolerance affects results.

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Informational tool. It does not replace testing, measurement or professional advice when needed.

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Frequently asked questions

Why is Req lower than the smallest branch resistor?+

Every added branch offers an additional current path.

Can I leave R3 blank?+

Yes, R3 is optional.