PCB Design & Engineering Calculators
Professional tools for trace width, via current, impedance, and clearance
Professional online PCB engineering toolkit. Get instant IPC-2221 results for trace width current capacity, via ampacity, impedance, and conductor clearance. Free accurate tools for PCB designers and hardware engineers.
Popular PCB Tools
Trace Width
Calculate required trace width for a target current and temperature rise
Impedance
Characteristic impedance for microstrip and stripline transmission lines
Via Current
Calculate via ampacity and temperature rise based on hole size and plating
Conductor Spacing
Calculate minimum clearance between traces to avoid arcing (IPC-2221)
Copper Weight
Convert between copper weight (oz/ft²) and physical thickness
Trace Resistance
Calculate DC resistance, voltage drop, and power loss for PCB traces
Differential Pair
Calculate differential impedance for balanced signal pairs
FAQ
What standards do these PCB calculators follow?
Our calculators for trace width and conductor spacing are based on the IPC-2221 standard, which is the industry benchmark for design requirements for printed boards.
How do I determine the right copper weight for my PCB?
Standard boards use 1 oz (35µm) copper. For high-current power supplies, 2 oz or 3 oz is preferred to reduce trace width and lower heat dissipation. Use our converter to check thicknesses.
Why is temperature rise important in PCB design?
Excessive heat can delaminate PCB layers, damage components, or cause trace failure. Designers typically aim for a 10°C to 20°C temperature rise for safe operation.
What is the IPC-2221 trace width formula?
IPC-2221 sizes a conductor from its cross-sectional area: A = (I / (k × ΔT^0.44))^(1/0.725), where I is current in amps, ΔT is the allowed temperature rise in °C, and k is 0.048 for external layers or 0.024 for internal layers. As a worked example, carrying 5 A with a 10°C rise on 1 oz external copper needs about 150 mil² of area, which is roughly 109 mil (about 2.77 mm) wide. Internal traces need more than double the width because they cannot shed heat to the surrounding air.
How much current can a single via carry?
Via ampacity depends on the copper barrel's annular area, A = π × drill_diameter × plating_thickness, fed into the same IPC-2221 current equation. A 0.3 mm drilled through-hole plated to 25 µm gives about 36.5 mil² of copper and carries roughly 1.8 A at a 10°C rise. Because a single via is current-limited, designers parallel several vias under power pads to stay within thermal limits.
What copper thickness does 1 oz/ft² correspond to?
Copper weight describes how much copper is spread over one square foot. One ounce equals 1.378 mil, 35 µm, or 0.035 mm of finished thickness; 2 oz is double that. Thicker copper lowers sheet resistance and raises current capacity for the same trace width, which is why power and motor-control boards often specify 2 oz or 3 oz outer layers.
How is PCB trace resistance and voltage drop calculated?
Trace resistance follows R = ρ × L / (W × t), using copper resistivity ρ = 1.724×10⁻⁶ Ω·cm at 20°C. Resistance rises with temperature through R_T = R_20 × (1 + α × (T − 20)), where α = 0.00393 /°C, so a trace running hot drops more voltage than its room-temperature value suggests. Multiply resistance by current for voltage drop, and by current squared for power loss, when budgeting for sensitive supply rails.