liminfoPCB Thermal Calculator
Free web tool: PCB Thermal Calculator
Temperature Rise
4.32 \u00b0C
Final Temperature
29.32 \u00b0C
Max Current (for max ΔT)
1.45 A
Min Trace Width (for max ΔT)
0.300 mm
Resistance (mΩ/m)
1021.2
Voltage Drop (V/m)
1.0212
Cross-section Area: 27.1 mil² | Power Loss: 1021.22 mW/m
About PCB Thermal Calculator
The PCB Trace Thermal Calculator helps electronics engineers and PCB designers determine the thermal performance of copper traces on printed circuit boards. By entering the trace width, copper weight (0.5 oz to 4 oz), current load, ambient temperature, and allowable temperature rise, you instantly get the expected temperature rise, the final operating temperature, and the maximum safe current the trace can carry — all calculated using the IPC-2152 standard formula.
This tool is widely used by hardware engineers designing power electronics, motor drivers, battery management systems, and any circuit where trace heating is a concern. The IPC-2152 model differentiates between external and internal copper layers, since external traces benefit from air convection and cool more effectively than traces buried inside a multilayer board. The calculator computes both the forward problem (temperature rise for a given current) and the inverse problem (maximum current for a given temperature rise and minimum trace width).
Technically, the tool uses the IPC-2152 simplified empirical formula I = k × ΔT^0.44 × A^0.725, where k equals 0.048 for external layers and 0.024 for internal layers, and A is the cross-sectional area in square mils. It also derives copper trace resistance using the temperature-corrected resistivity of copper (ρ = 1.724×10⁻⁸ Ω·m at 20°C, with a temperature coefficient of 0.00393/°C) and computes voltage drop and power loss per meter of trace length.
Key Features
- IPC-2152 compliant temperature rise calculation for external and internal PCB layers
- Supports copper weights of 0.5 oz, 1 oz, 2 oz, 3 oz, and 4 oz
- Calculates maximum allowable current for a user-specified temperature rise limit
- Computes minimum trace width required to stay within a thermal budget
- Displays trace resistance in mΩ/m with temperature-corrected copper resistivity
- Shows voltage drop (V/m) and power dissipation (mW/m) per unit length
- Real-time color-coded feedback: green when within thermal limits, red when exceeded
- 100% browser-based calculation — no data sent to any server, works offline
Frequently Asked Questions
What standard does this PCB thermal calculator use?
It implements the IPC-2152 empirical model, which is the industry standard for estimating current-carrying capacity and temperature rise in PCB copper traces. The formula is I = k × ΔT^0.44 × A^0.725, with k = 0.048 for external layers and k = 0.024 for internal layers.
Why does the internal layer use a different coefficient than the external layer?
External copper traces can dissipate heat to the surrounding air through convection, making them more efficient at heat removal. Internal traces are surrounded by FR4 laminate, which has much lower thermal conductivity than air, so they heat up approximately twice as much for the same current. IPC-2152 captures this with k = 0.048 (external) vs k = 0.024 (internal).
What is "1 oz copper" in terms of thickness?
Copper weight refers to the mass of copper per square foot of board area. 1 oz copper corresponds to a thickness of 0.035 mm (35 µm). 2 oz copper is 0.07 mm thick, 0.5 oz is 0.0175 mm, and so on. Thicker copper reduces resistance and increases current-carrying capacity.
How is the minimum trace width calculated?
The minimum trace width is derived by rearranging the IPC-2152 formula to solve for cross-sectional area: A_min = (I / (k × ΔT^0.44))^(1/0.725). The resulting area in square mils is then divided by the copper thickness in mils to get the minimum width in mils, which is converted to millimeters.
What formula is used for trace resistance?
Resistance per meter is calculated as R = ρ(T) / (w × t), where w and t are the width and thickness in meters, and ρ(T) = ρ₂₀ × (1 + 0.00393 × (T − 20)) is the temperature-corrected resistivity of copper. This accounts for the fact that copper resistance increases with temperature.
What is a reasonable temperature rise limit for PCB traces?
IPC-2152 recommends a maximum temperature rise of 10°C to 20°C above ambient for most applications. Safety-critical or high-reliability designs often target 10°C. Consumer electronics may allow up to 20°C–30°C. The final temperature (ambient + rise) should stay well below the glass transition temperature (Tg) of the PCB laminate, typically 130°C–175°C for FR4.
Can I use this calculator for high-current bus bars or very thick copper?
This calculator is optimized for standard PCB copper weights up to 4 oz. For very heavy copper (above 4 oz) or bus bars, the IPC-2152 simplified model may underestimate performance. In those cases, a full thermal simulation using tools like HyperLynx or Saturn PCB Design Toolkit is recommended.
Does trace length affect the temperature rise calculation?
The IPC-2152 temperature rise formula is independent of trace length — it depends only on the cross-sectional area and current. However, trace length directly affects total resistance, total voltage drop, and total power dissipation, which this tool calculates as per-meter values that you can scale by your actual trace length.