Voltage Drop Table: Voltage drop by Current
Reference table of voltage drop for Voltage Drop across a range of current values — exact, engine-computed figures you can read off at a glance.
Voltage Drop Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Voltage drop
2.800
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Voltage Drop Calculator
The Voltage Drop Calculator works out your voltage drop in an instant. Enter current, one-way cable length and conductor area and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the current.
- Enter the one-way cable length.
- Enter the conductor area.
- Enter the resistivity (Ω·mm²/m).
- Read off your voltage drop — the calculator updates automatically, with no button to press.
Formula
The Voltage Drop Calculator uses the formula:
Voltage drop = 2 × Current × Resistivity (Ω·mm² ÷ m) × One-way cable length ÷ Conductor area
Worked example
For example, with current of 10 A, one-way cable length of 20 m, conductor area of 2.5 mm² and resistivity (Ω·mm²/m) of 0.0175, the voltage drop is 2.800.
| Current | 10 A |
|---|---|
| One-way cable length | 20 m |
| Conductor area | 2.5 mm² |
| Resistivity (Ω·mm²/m) | 0.0175 |
| Voltage drop | 2.800 |
|---|
Results are estimates for educational use, not professional advice.
Key terms explained
- Area
- The amount of two-dimensional space a shape covers, measured in square units.
Frequently asked questions
Voltage drop = 2 × current × resistivity × length ÷ area, where the factor of 2 covers the out-and-return conductors. The default example is about 2.8 V.
Excess drop dims lights, weakens motors and wastes energy as heat. Codes usually limit drop to a few percent of supply voltage.
Use a larger conductor area, shorten the cable run, or reduce the current. Thicker cable is the most common fix for long runs.
Current flows out to the load and back, so the total conductor length is twice the one-way distance you enter.
Enter the current. Enter the one-way cable length. Enter the conductor area. Enter the resistivity (Ω·mm²/m). Read off your voltage drop — the calculator updates automatically, with no button to press.
Related guides
How to Calculate Voltage Drop: Formula, Steps & Examples
Learn how to calculate Voltage Drop — the formula explained step by step, with worked examples and a free calculator to check your answer.