Calculators / PCB trace width

PCB trace width

Minimum trace width for a given current and temperature rise, per IPC-2221, for outer and inner copper at the weight you specify.

tune

Trace Parameters

Current (I) Amps

1.0 A

Temperature Rise (ΔT) °C

10 °C

Typical: 10°C (safe), 20–30°C (acceptable), >40°C (check reliability)

Copper Weight

Layer

Internal layers use k=0.024 (IPC-2221) — approximately half the current capacity of external layers (k=0.048).

rule

Trace Width Checker

Check Width mil (optional)

Enter a specific trace width to calculate its maximum current capacity and safety margin.

info

Enter a trace width above to verify capacity and safety margin.

Min Trace Width
—mil

Cross-Section Area
—mil²

Resistance / inch

—mΩ/in

show_chart

Trace Width vs. Current Capacity

Current-carrying capacity at your selected ΔT. ● marks the minimum width for your input current.

IPC-2221 Table 6-1 Formula:
Area (mil²) = (I / (k × ΔT^0.44))^1/0.725
Where k = 0.048 for external layers, k = 0.024 for internal layers. Copper thickness: 1 oz/ft² = 1.378 mil (35 µm).

functions IPC-2221 Equations

Area (mil²)= (I / (k × ΔT^0.44))^(1/0.725) Width (mil)= Area / Thickness_mil k_ext= 0.048 (external layer) k_int= 0.024 (internal layer, ×0.5 derating) I_max= k × ΔT^0.44 × Area^0.725 (inverse)

Need the whole power tree?

The editor solves every rail at once: voltages, currents, losses and warnings as you draw.

Launch the app

These tools and articles give theoretical estimates for educational purposes. Real results depend on component tolerances, parasitics and thermal conditions.