Science & Engineering

Kirchhoff

Uses Kirchhoff's Voltage Law (sum of voltages around a loop is zero) to find the remaining voltage drop after subtracting two known drops from the source voltage.

What this calculator does

The Kirchhoff estimates your result instantly from the values you enter, using standard science & engineering formulas. Uses Kirchhoff's Voltage Law (sum of voltages around a loop is zero) to find the remaining voltage drop after subtracting two known drops from the source voltage. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.

Kirchhoff's Voltage Law Calculator

Result

—
Remaining Drop (V)

About Kirchhoff

This calculator applies Kirchhoff's Voltage Law, which states that the voltages around a closed loop sum to zero (ΣV = 0). Given a source voltage and two known voltage drops, it returns the remaining drop as V3 = Vsource − V1 − V2.

All values are in volts. A negative result means the remaining element would need to supply voltage rather than drop it, which can flag an inconsistent set of inputs.

Formula & Mathematical Calculation

Remaining Drop (V) = f(Source Voltage (V), Voltage Drop 1 (V), Voltage Drop 2 (V))

Calculated according to standard science formulas implemented in the calculator core.

Calculation Example

With a source voltage of 12 V and two drops of 4 V and 5 V, the remaining drop is 12 − 4 − 5 = 3 V, satisfying ΣV = 0 around the loop.

Key Benefits

  • Applies Kirchhoff's Voltage Law so the loop voltages balance to zero
  • Finds the third voltage drop by subtracting two known drops from the source
  • Accepts negative entries for sources or drops in either direction
  • Returns the remaining drop in volts to four decimal places

How to Use this Calculator

  1. Enter the source voltage
    Type the loop's source voltage in volts in the Source Voltage (V) field.
  2. Enter the first voltage drop
    Type the first known drop in volts in the Voltage Drop 1 (V) field.
  3. Enter the second voltage drop
    Type the second known drop in volts in the Voltage Drop 2 (V) field, then press Calculate.

Assumptions & Limitations

What the calculation assumes

  • Every value you enter is treated as an exact, known amount.
  • Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
  • Results use standard published formulas and account only for the values entered above.
  • Rounding is applied for display; the underlying calculation uses your full precision.
  • Results are returned in the same units you enter, unless the tool states the output unit.

What it does not cover

  • Kirchhoff produces a calculated result for reference and learning, not a certified or official measurement.
  • Real-world outcomes differ when tolerances, rounding rules or local standards apply.
  • Definitions and standards vary by region and change over time; verify the convention that applies to your case.
  • Figures are only as accurate as the inputs you supply — check them before acting on the result.
  • For work where the result carries real consequences, confirm it against an authoritative source.

Frequently Asked Questions

It uses Kirchhoff's Voltage Law: the sum of all voltages around a closed loop is zero, so the remaining drop equals the source voltage minus the two known drops.

A negative result means the two entered drops already exceed the source voltage, which usually signals an inconsistent set of inputs for a passive series loop.

This tool takes the source voltage and two known drops, then solves for the single remaining drop in the loop.

Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.