Series & Parallel Resistor Calculator
Find the equivalent resistance of resistors in series or parallel, with each resistor's current, voltage, and power
About this calculator
The Series & Parallel Resistor Calculator finds the equivalent resistance of 2 to 10 resistors, using R = R₁ + R₂ + … for series and 1/R = 1/R₁ + 1/R₂ + … for parallel, with high-precision decimal math. Add a supply voltage to get each resistor's current, voltage drop, and power plus the total current and power, drawn on a schematic whose widths follow the current (parallel) or voltage drop (series). Each value is checked separately, so a zero, negative, or mistyped resistance is pointed out by position.
How to use the Series & Parallel Resistor Calculator calculator
- Enter the quantities you know, using the units shown on each field.
- Read the computed results — they update instantly as you type.
- Use the visual explanation to see how the quantities relate.
- Copy the page URL to share the exact calculation.
Common examples
- Series 100 Ω + 220 Ω + 330 Ω → 650 Ω
- Parallel 100 Ω ∥ 220 Ω → 68.75 Ω
- Parallel 100 Ω ∥ 220 Ω ∥ 330 Ω → 3300/58 ≈ 56.897 Ω
- Parallel 100 Ω ∥ 220 Ω at 12 V → I₁ 0.12 A, I₂ 0.0545 A, total 0.1745 A (2.09 W)
- Series 100 Ω + 220 Ω + 330 Ω at 13 V → 20 mA; drops 2 V, 4.4 V, 6.6 V
Frequently asked questions
How does the Series & Parallel Resistor Calculator calculator work?
Enter the known quantities and the calculator applies the governing physical law or scientific formula to find the unknowns, stating the equation it used and the units of every result. Computations run at high precision.
When would I use the Series & Parallel Resistor Calculator calculator?
It suits physics and chemistry homework, lab work, engineering estimates, and any time you want to explore how changing one quantity affects the others in a well-defined scientific relationship.
How accurate are the results?
The formula itself is evaluated at 30 significant digits of precision. Keep in mind that idealized models — such as neglecting friction, air resistance or measurement error — bound the real-world accuracy more than the arithmetic does.
Can I share a specific calculation with someone else?
Yes. Every value you enter updates the URL, so copying the address bar and sharing the link reopens the exact same calculation for whoever clicks it.