Resistance Circuit Inputs
Example Data Table
| Case | Type | Voltage (V) | Resistors (Ω) | Equivalent Resistance (Ω) | Total Current (A) |
|---|---|---|---|---|---|
| Example 1 | Series | 12 | 10, 20, 30 | 60.0000 | 0.2000 |
| Example 2 | Parallel | 24 | 100, 200, 300 | 54.5455 | 0.4400 |
| Example 3 | Series-Parallel | 18 | Branch A: 10, 15 | Branch B: 20, 30 | 16.6667 | 1.0800 |
Formula Used
The calculator applies standard resistance network formulas and then adjusts each resistor using tolerance and temperature shift data.
1) Adjusted resistor value
Adjusted Resistance = Nominal Resistance × Tolerance Multiplier × Temperature Multiplier
Temperature Multiplier = 1 + ((ppm/1,000,000) × (Operating Temp - Reference Temp))
2) Series circuit
Equivalent Resistance = R1 + R2 + R3 + ...
Total Current = Supply Voltage / Equivalent Resistance
Voltage Drop Across One Resistor = Current × Resistor Value
Power In One Resistor = Current² × Resistor Value
3) Parallel circuit
1 / Equivalent Resistance = 1/R1 + 1/R2 + 1/R3 + ...
Branch Current = Supply Voltage / Branch Resistance
Power In One Branch = Voltage × Current
4) Two-branch series-parallel circuit
Branch A Resistance = R1 + R2 + R3
Branch B Resistance = R4 + R5 + R6
Equivalent Resistance = 1 / ((1/Branch A) + (1/Branch B))
Total Power = Supply Voltage × Total Current
Energy = Total Power × Hours
How to Use This Calculator
Choose the circuit arrangement first. Select series for one current path, parallel for equal branch voltage, or series-parallel for two grouped branches.
Enter the supply voltage and planned runtime. Runtime is used for watt-hour estimation and helps compare energy use between different resistor networks.
Add up to six resistor values in ohms. Any field with zero stays inactive, so you can model smaller circuits without removing form fields.
If tolerance matters, enter the percentage and pick nominal, high-side, or low-side analysis. This helps you estimate best-case or worst-case resistance spread.
Enter the temperature coefficient, reference temperature, and operating temperature when thermal drift matters. The adjusted resistance values will update during the calculation.
Submit the form. The result section appears above the form and shows equivalent resistance, total current, total power, resistor-by-resistor values, summary data, and a graph of power dissipation.
Use the CSV button for spreadsheet review. Use the PDF button when you need a printable record, calculation proof, or client-ready report.
FAQs
1) What circuit types does this calculator support?
It supports series, parallel, and a two-branch series-parallel layout. The mixed option treats R1 to R3 as Branch A and R4 to R6 as Branch B.
2) How does tolerance affect the answer?
Tolerance shifts the resistor away from nominal value. High-side increases resistance, low-side decreases resistance, and nominal leaves the entered value unchanged.
3) Why include temperature coefficient?
Real resistors drift with temperature. The temperature coefficient helps estimate resistance change between a reference condition and the actual operating condition.
4) Can I leave some resistor fields empty?
Yes. Zero-valued fields remain inactive. This lets you analyze smaller networks while still using the same calculator layout.
5) What does the power graph show?
The chart plots resistor power dissipation in watts. It helps identify which resistor runs hardest and may need a higher wattage rating.
6) Is the PDF export automatic?
The PDF button creates a downloadable document from the result block. It is useful for records, proposals, technical notes, and client handoffs.
7) Does the calculator work for DC analysis?
Yes. It is designed for steady-state resistance calculations using Ohm’s law. It does not model reactance, transients, or frequency-dependent AC behavior.
8) Can I use this for resistor selection?
Yes. It helps compare equivalent resistance, branch current, and dissipation. That makes preliminary resistor sizing and network checks much faster.