Series Resistors Calculator
Add two resistor values to find their total series resistance.
01 / INPUTS
Ω
Ω
02 / RESULT
TOTAL RESISTANCE
300 Ω
- Total resistance
- 300 Ω
Calculation trace
- 100 Ω + 200 Ω = 300 Ω300 ΩSeries resistance
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How it works
For the two entered resistances, the tool adds them directly: Rtotal = R1 + R2. In a series connection the same current passes through both resistors, so their voltage drops add.
Assumptions & limits
- Calculates exactly two ideal, positive, finite resistances connected in series.
- Does not model resistor tolerance, temperature dependence or parasitic reactance.
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FAQ
- Why is series resistance the sum of the resistors?
- The same current flows through each resistor, and the total voltage drop is the sum of their individual I·R drops, giving Rtotal = R1 + R2.
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SOURCES
- International Electrotechnical Commission (IEC)IEC 60050 — International Electrotechnical Vocabulary (Electropedia) ↗
Series resistance: total resistance is the sum of the resistances
Accessed 2026-08-19
- Bureau International des Poids et Mesures (BIPM)The International System of Units (SI), 9th edition ↗
SI derived unit: ohm
Accessed 2026-08-19