Trace Voltage Drop
Vdrop = I × R
Quick answer
This calculator solves Vdrop = I × R for Voltage Drop. With Current 2 A, Trace Resistance 0.47 kΩ, the result is 0.94 kV. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
Voltage drop across a PCB trace is a direct application of Ohm's law. Even small resistances become significant at high currents or when supplying low-voltage devices. For example, a 0.1Ω trace carrying 3A drops 0.3V, which is 9% of a 3.3V supply and may cause improper operation of downstream ICs. This is why power traces should be wide and short, and why sensitive circuits should have their own power connections close to the voltage regulator rather than sharing long traces with high-current loads.
Variables
- Vdrop — Voltage drop across the trace (V)
- I — Current through the trace (A)
- R — Trace resistance (Ω)
Practical Notes
Maximum acceptable voltage drop is typically 1-3% of the supply voltage for digital logic and 1% or less for analog circuits. Use copper pours and polygon fills for power distribution. Kelvin (4-wire) sensing at the load point can compensate for trace drops in precision applications. Remote voltage sensing on DC-DC converters compensates for PCB trace drops automatically.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| Vdrop | Voltage Drop | mV | pV, nV, µV, mV, V, kV |
| I | Current | A | pA, nA, µA, mA, A, kA |
| R | Trace Resistance | Ω | mΩ, Ω, kΩ, MΩ |
Step by step
- 1. What you know: Current 2 A, Trace Resistance 0.47 kΩ
- 2. The relation: Vdrop = I × R
- 3. Substitute: I = 2 A, R = 0.47 kΩ
- 4. Result: Voltage Drop = 0.94 kV
Related quantities from the same inputs
- P = V × I = 1.88 kW
Worked examples
Minimum range
Given: Current 2 mA, Trace Resistance 1 Ω
Result: Voltage Drop = 2 mV
Low range
Given: Current 20 mA, Trace Resistance 10 Ω
Result: Voltage Drop = 0.2 V
Typical
Given: Current 2 A, Trace Resistance 0.47 kΩ
Result: Voltage Drop = 0.94 kV
High range
Given: Current 100 A, Trace Resistance 4.7 kΩ
Result: Voltage Drop = 470 kV
Maximum range
Given: Current 1 kA, Trace Resistance 47 kΩ
Result: Voltage Drop = 47000 kV
Solving for each variable
Solve for Voltage Drop
Current 2 mA, Trace Resistance 1 Ω → 2 mV
Solve for Current
Voltage Drop 10 mV, Trace Resistance 1 Ω → 10 mA
Solve for Trace Resistance
Voltage Drop 10 mV, Current 2 mA → 5 Ω
How Voltage Drop changes with Current
| Current (input) | Voltage Drop (result) |
|---|---|
| 0.2 A | 94 V |
| 0.5 A | 0.235 kV |
| 1 A | 0.47 kV |
| 1.5 A | 0.705 kV |
| 2 A | 0.94 kV |
| 3 A | 1.41 kV |
| 4 A | 1.88 kV |
| 8 A | 3.76 kV |
| 14 A | 6.58 kV |
| 20 A | 9.4 kV |
The same result in other units
| Unit | Value |
|---|---|
| mV | 940000 |
| V | 940 |
| kV | 0.94 |
Embed this calculator
Paste this into any page. It keeps working when this page updates, and credits the source.
<iframe src="https://vbatpower.com/embed/trace-voltage-drop/" width="100%" height="460" style="border:1px solid #1f2a37;border-radius:12px" loading="lazy" title="Trace Voltage Drop"></iframe>
<p><a href="https://vbatpower.com/formulas/trace-voltage-drop/">Trace Voltage Drop</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Trace Voltage Drop?
Use Vdrop = I × R. With Current 2 A, Trace Resistance 0.47 kΩ, Voltage Drop works out to 0.94 kV.
What is the formula for Trace Voltage Drop?
The formula is Vdrop = I × R. Voltage drop across a PCB trace is a direct application of Ohm's law.
How do you find Current when you know the other values?
Rearrange for Current: with Voltage Drop 10 mV, Trace Resistance 1 Ω, Current is 10 mA.
How do you find Trace Resistance when you know the other values?
Rearrange for Trace Resistance: with Voltage Drop 10 mV, Current 2 mA, Trace Resistance is 5 Ω.
What units does Trace Voltage Drop use?
Voltage Drop is shown in mV, V, kV. Values are held in SI base units internally, so you can mix prefixes without converting by hand.
Related Concepts
All PCB & Traces formulas →Need more features?
Save calculations, import telemetry data, simulate battery discharge, and collaborate with your team.
Try the App