PCB Trace Width Calculator
Professional PCB Design & Analysis Tools
Calculate PCB trace width from current, temperature rise, and copper weight using the IPC-2221 empirical power-law. Our free online trace width calculator helps hardware engineers estimate the minimum conductor width for a given current, temperature rise, and copper weight.
IPC-2221 Power-Law Model
Our PCB trace width calculator applies the IPC-2221 empirical formula (I = k × ΔT^0.44 × A^0.725). The result is an estimate: confirm critical designs against your fabricator's stackup and a thermal measurement or field solver.
Width, Resistance, Voltage Drop and Power
Each run reports trace width, resistance, voltage drop and power dissipation. Supports both internal and external layer calculations with automatic unit conversion between mils and millimeters.
Via Current and Impedance Calculators
Beyond basic trace width calculation, access our complete tool suite including via current calculator and impedance calculator for the rest of the power and signal path.
Input Parameters
MOD: TR_WID_V1Results
Analysis & Recommendations
Design Guidance
- •1A on External layer, min width: 0.30mm
- •Add 10-20% safety margin. Recommended: 0.35mm
- •Cross-sectional area: 16.30 mil² (0.0105 mm²)
Electrical Impact
- •Resistance (10mm trace): 17.04 mΩ
- •Voltage drop: 17.04 mV
- •Power dissipation: 17.04 mW
IPC-2221 Calculation Method
This calculation uses the IPC-2221 standard formula: I = k × ΔT^b × A^c where k=0.048, b=0.44, c=0.725. External layers dissipate heat more effectively to surrounding air
How to Use the PCB Trace Width Calculator
- Design Current: the continuous current the trace must carry, in amps.
- Temperature Rise: how far above ambient the copper may heat; 10 °C is a common conservative choice.
- Copper Thickness: finished copper weight in oz/ft² (1 oz is taken as 1.37 mil, 0.0348 mm).
- Layer Type: external (outer) layers use k = 0.048; internal layers use k = 0.024 and need roughly 2.6× the cross-section for the same current.
- Trace Length: only affects resistance, voltage drop and power loss, not the minimum width.
Worked example (computed with this calculator's IPC-2221 formula)
1 A, 10 °C rise, 1 oz copper, external layer: A = (1 / (0.048 × 100.44))1/0.725 ≈ 16.3 mil², so width ≈ 16.3 / 1.37 ≈ 11.9 mil (0.30 mm). The same current on an internal layer needs ≈ 42.4 mil², about 30.9 mil (0.79 mm). Results are IPC-2221 estimates; see the methodology page for constants and test vectors.
Why Use Our PCB Trace Width Calculator?
Thermal Design Optimization
Choose the temperature rise your board can tolerate (10 °C is a common conservative default) and the PCB trace width calculator returns the minimum copper cross-section from the IPC-2221 formula. A lower allowed rise gives a wider trace and more thermal margin; results are estimates.
Internal vs External Layer Support
Under the IPC-2221 formula, an internal layer (k=0.024) carries about half the current of an external layer (k=0.048) at the same copper cross-section and temperature rise. Our trace calculator applies these constants; the result is an estimate.
Complete Electrical Analysis
Beyond trace width, calculate DC resistance, voltage drop, and power loss to ensure your power distribution network meets design requirements.
High Current Designs (1A - 35A+)
IPC-2221 curves are commonly cited as valid up to about 35 A, 400 mil width, 0.5–3 oz copper and a 10–100 °C rise; outside that range the formula is an extrapolation. For high-current paths, consider heavier copper, parallel layers or pours, and confirm with a thermal measurement or field solver.
Copy & Export Results
Easily copy calculated trace widths and parameters for documentation, design reviews, or integration into your PCB CAD software.
100% Free, No Registration
Instant access to PCB trace calculations in the browser. No signup, no subscription, unlimited use.
Complete PCB Design Calculator Suite
Our trace width calculator is part of a comprehensive toolkit for PCB designers. Use these companion tools for complete electrical and thermal analysis.
Via Current Calculator
LIVECalculate via current carrying capacity based on IPC-2221 standard. Free tool for plated through-hole thermal analysis and via array design optimization.
Try Calculator →Impedance Calculator
LIVEEstimate single-ended Z0 for isolated microstrip and stripline traces. Confirm the stackup and model limits with your fabricator.
Try Calculator →Frequently Asked Questions
PCB Trace Width Quick Reference
*Approximate values at 10°C rise. Use calculator for precise results.
Via Current Reference
→ Full Via CalculatorIPC-2221 Standard Formula
- I = Current (Amps)
- k = 0.048 (External) / 0.024 (Internal)
- ΔT = Temperature Rise (°C)
- A = Cross-sectional Area (mil²)
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Other PCB Calculators
Via Current Calculator
Calculate via current carrying capacity based on IPC-2221 standard. Free tool for plated through-hole thermal analysis and via array design optimization.
Try Calculator →Impedance Calculator
Estimate single-ended Z0 for isolated microstrip and stripline traces. Confirm the stackup and model limits with your fabricator.
Try Calculator →Related Tools & Resources
Via Current Calculator
CalculatorCalculate via current carrying capacity based on IPC-2221 standard. Free tool for plated through-hole thermal analysis and via array design optimization.
Impedance Calculator
CalculatorEstimate single-ended Z0 for isolated microstrip and stripline traces. Confirm the stackup and model limits with your fabricator.
Current Capacity Calculator
CalculatorDetermine maximum current a trace can safely carry
Differential impedance reference (numeric results unavailable)
CalculatorReference for differential pair impedance targets and routing rules. Numeric differential calculation is temporarily unavailable while the model is validated; single-ended Z0 is available.
Pad Size Calculator
CalculatorCalculate pad diameter and area from hole size and annular ring
Thermal Relief Calculator
CalculatorDesign thermal relief patterns for solderable plane connections
Ready to Calculate Your PCB Trace Width?
Use the free IPC-2221 trace width calculator above, or explore our other PCB design tools for comprehensive electrical analysis. Check out our blog for in-depth PCB design guides and tutorials.