Resistor Calculator 🛡️ 100% Client‑Side

Smart units · E‑series finder · Real‑time
Add Resistor
Total Parallel Resistance
0 Ω
Find Standard Resistor Combination

Finds the closest parallel combination of two standard resistors.

📘 Resistors in Series & Parallel

In series, total resistance is the sum of all resistors. In parallel, the reciprocal of total resistance equals the sum of reciprocals. This tool supports smart unit input (e.g., 10k, 1M) and can find the closest standard resistor combination for a target value.

❓ Frequently Asked Questions

How do I calculate parallel resistance?

1/R_total = 1/R1 + 1/R2 + ... + 1/Rn. The total is always less than the smallest resistor.

What are E‑series standard values?

E12, E24, etc. define standard resistor values based on tolerance. E24 has 24 values per decade (5% tolerance).

Can I use units like '10k'?

Yes, the calculator supports k (kilo), M (mega), and R (ohms).