Electrical Fundamentals
Current Divider Calculator
Use Current Divider when current through R1 is the quantity you need. Enter total current, branch resistance R1, and branch resistance R2, then compare the answer with the equipment or operating limits that apply to your case.
Enter values for Current through R1
Check the source and units before calculating.
Input notes
Keep source conditions with each voltage, current, resistance, or charge value. Do not combine a worst-case value with unrelated nominal data.
Values used below a division bar must stay positive. A prefix error can move the result by several orders of magnitude. If you also need battery heat, continue with Battery Heat Generation Calculator.
- Total current
- Default example: 3 A. Enter total current in A.
- Branch resistance R1
- Default example: 10 Ω. Enter branch resistance R1 in Ω.
- Branch resistance R2
- Default example: 20 Ω. Enter branch resistance R2 in Ω.
Common entry mistakes
A plausible-looking output does not prove that the entries are compatible.
Compare the magnitude with a quick independent estimate.
Understanding the equation
The displayed result follows I1 = Itotal × R2 ÷ (R1 + R2). The formula draws on Total current, Branch resistance R1, and Branch resistance R2.
With the current entries, the primary answer is 2.00 A. Preserve the raw inputs when replacing this example.
Calculate current through R1 from total current, branch resistance R1, and branch resistance R2. The broader analysis may also use Loaded Voltage Divider Calculator.
Applying the result
Read Current through R1 as the outcome of this equation, not as automatic equipment approval. Compare it with bench measurements and component ratings.
Keep the input set beside the output so another reader can reproduce it.
Changing Total current
Change Total current from 3 A to 3.5999999999999996 A with every other entry unchanged. The result changes from 2.00 A to 2.40 A.
Do not average the two cases if either could define an operating limit.
Where this estimate can fail
Reactive or nonlinear branches require impedance rather than resistance alone.
Outside the entered variables, consider instrument loading, transient behavior, and component tolerance. Document which effects were checked elsewhere in the analysis.
Record conductor temperature and whether values are measured, nominal, or calculated.
Questions from practical use
What precision should move to the next worksheet?
Do not round between dependent calculations. Match the final display to the precision of the source data.
Which entries must stay above zero?
Use a measured positive value for Branch resistance R1 and Branch resistance R2; zero cannot stand in for missing data.