PCB Copper Thickness Calculator
Convert PCB copper thickness between ounces per square foot, micrometers, millimeters, and mils for fabrication and layout work.
Enter a trace width to calculate conductor cross-sectional area for resistance, current-capacity, voltage-drop, and thermal design checks.
Engineering tool
PCB Copper Thickness Calculator
Convert PCB copper weight and thickness units, then calculate conductor cross-sectional area.
Enter base or finished copper thickness in oz, µm, mm, or mil.
Trace width is used to calculate the copper cross-sectional area.
Result console
- Copper thickness
- 1oz
- Copper thickness
- 34.79µm
- Copper thickness
- 0.03479mm
- Copper thickness
- 1.369685mil
- Cross-sectional area
- 0.03479mm²
- Cross-sectional area
- 53.924608mil²
Use finished copper thickness, including plating where applicable, when checking trace resistance and current capacity. Confirm the fabrication tolerance with the PCB manufacturer.
Formula reference
PCB Copper Thickness Conversion Formulas
Copper weight is converted through nominal thickness in micrometers. Cross-sectional area uses trace width and copper thickness in matching units.
1 oz copper ≈ 34.79 µm1 mil = 25.4 µm1 mm = 1000 µmCross-sectional area: A = W × tVariable definitions
- oz
- copper weight in ounces per square foot
- W
- finished trace width
- t
- finished copper thickness
- A
- copper conductor cross-sectional area
Copper Thickness Conversion Table
| Copper weight | Micrometers | Millimeters | Mils |
|---|---|---|---|
| 0.5 oz | 17.40 µm | 0.01740 mm | 0.685 mil |
| 1 oz | 34.79 µm | 0.03479 mm | 1.370 mil |
| 2 oz | 69.58 µm | 0.06958 mm | 2.739 mil |
| 3 oz | 104.37 µm | 0.10437 mm | 4.109 mil |
Worked Example
For 1 oz copper and a 1 mm trace, the nominal thickness is 34.79 µm, or 0.03479 mm and approximately 1.37 mil.
A = 1 mm × 0.03479 mm = 0.03479 mm². Finished copper may differ because of foil tolerance and plating.
Engineering Notes
- PCB copper thickness is commonly specified in ounces per square foot.
- One ounce copper is approximately 34.79 µm using the nominal conversion.
- Finished copper thickness may differ from base copper because of plating.
- Copper thickness affects trace resistance, current capacity, voltage drop, and temperature rise.
- Always confirm finished copper thickness and tolerance with the PCB manufacturer.
Support reference
FAQ
How thick is 1 oz PCB copper?
One ounce of PCB copper is approximately 34.79 µm, 0.03479 mm, or 1.37 mil thick. Finished thickness can vary with fabrication and plating.
What is 2 oz copper thickness?
Using the nominal conversion, 2 oz copper is approximately 69.58 µm, 0.06958 mm, or 2.74 mil thick.
How do you convert PCB copper oz to microns?
Multiply copper weight in ounces per square foot by 34.79. For example, 1.5 oz × 34.79 gives approximately 52.19 µm.
Does plating change copper thickness?
Yes. Outer-layer traces may receive additional copper during through-hole plating, so finished copper can be thicker than the starting foil. Confirm the finished value with the fabricator.
Why does copper thickness matter for current capacity?
Thicker copper increases conductor cross-sectional area, reducing resistance, voltage drop, and I²R heating while improving current-carrying capability.
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