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PCB COPPER SPECIFICATION TOOL
PCB Copper Weight Converter
Convert PCB copper weight between oz/ft², micrometers, millimeters, and mils. Add outer-layer plating, compare base foil with finished copper, and estimate copper mass from board area, layer count, and average coverage.
oz/ft², µm, mm, and mil
Base foil and finished copper
Optional board copper mass estimate
AREA WEIGHT
FINISHED BUILD
FOIL CLASS
1.00 oz
NOMINAL BASE
35.0 µm
FINISHED COPPER
60.0 µm
INTERACTIVE COPPER BUILD CONVERTER
Convert Copper Weight, Finished Thickness, and Board Mass
Start from an area-weight class or a measured thickness. Add optional outer-layer plating and use the area inputs only when a physical copper-mass estimate is needed.
CONVERSION INPUTS
Foil, Plating, and Area
oz/ft²
Area-weight class before additional plating.
µm
Measured or specified base-foil thickness.
Quickly load a common copper class.
µm
Enter zero for inner layers or unplated foil.
%
Average retained copper, not the full board area.
layers
Layers carrying the selected base foil.
layers
Normally zero, one, or two outer layers.
FINISHED COPPER MODEL
1 oz Base Foil with Plating
FINISHED
PLATING
BASE FOIL
DIELECTRIC
35.0 µm
25.0 µm
- Base Weight
- 1.000 oz/ft²
- Base Thickness
- 35.0 µm
- Plating Addition
- 25.0 µm
- Finished Thickness
- 60.0 µm
Industry nominal foil conversion
Uses 35 µm per oz/ft² for common PCB specification work. Area weight remains the controlled foil property; actual finished copper varies with foil tolerance, etching, and plating.
Common PCB copper range
ESTIMATED FINISHED COPPER THICKNESS
60.0 µm
0.0600 mm · 2.362 mil
COPPER CLASS
Standard to heavy copper build
The finished equivalent is above 1 oz and below 2 oz. Confirm the fabricator’s finished-copper definition.
Base Foil Equivalent
1.000 oz/ft²
Finished Equivalent Weight
1.734 oz/ft²
Finished Thickness
0.0600 mm
Finished Thickness
2.362 mil
Finished Area Weight
529.2 g/m²
Plating Increase
71.4%
Estimated Copper Mass
8.34 g
Total Copper Volume
0.931 cm³
CONVERSION BASIS
Area Weight Is the Specification; Thickness Is a Nominal Equivalent
PCB copper foil is commonly ordered by ounces per square foot. The converter separates the familiar 35 µm-per-ounce convention from a density-derived physical conversion so the selected basis remains explicit.
Industry Nominal
Thickness = Copper Weight × 35 µm
Best for drawings, stackup discussions, quotation inputs, and common values such as 0.5 oz, 1 oz, 2 oz, and 3 oz.
Density-Derived
Thickness = Mass ÷ (Area × Copper Density)
Uses 8.96 g/cm³ copper density and the physical definition of one avoirdupois ounce spread across one square foot.
Finished Outer Copper
Finished Thickness = Base Foil + Plating
Outer-layer finished copper can exceed the starting foil because through-hole and surface plating add copper after lamination.
Area and Mass Estimate
Mass = Area × Coverage × Thickness × Density
The optional estimate assumes uniform average coverage across the selected layers and uniform plating across the plated outer layers.
COMMON FOIL CLASSES
PCB Copper Weight to Nominal Thickness Reference
These values use the common 35 µm-per-ounce PCB convention. Finished outer copper may be higher after plating.
| Copper Weight | Nominal µm | Nominal mm | Nominal mil | Typical Use |
|---|---|---|---|---|
| 0.5 oz | 17.5 µm | 0.0175 mm | 0.689 mil | Fine geometry and HDI starting foil |
| 1 oz | 35 µm | 0.0350 mm | 1.378 mil | General-purpose PCB copper |
| 1.5 oz | 52.5 µm | 0.0525 mm | 2.067 mil | Moderate current and plated outer layers |
| 2 oz | 70 µm | 0.0700 mm | 2.756 mil | Power distribution and industrial boards |
| 3 oz | 105 µm | 0.1050 mm | 4.134 mil | High-current copper construction |
| 4 oz | 140 µm | 0.1400 mm | 5.512 mil | Heavy-copper power structures |
| 6 oz | 210 µm | 0.2100 mm | 8.268 mil | Specialized heavy-copper fabrication |
INPUT QUALITY
Keep Base Foil, Plating, and Finished Copper Separate
The most common conversion error is treating starting foil weight and finished outer-layer thickness as the same specification.
Base Copper Weight
Use the foil class before electroplating. Inner layers normally remain close to the selected foil thickness after imaging and etching.
Finished Outer Copper
Add the specified plating build only when the drawing or fabricator defines finished outer copper as foil plus deposited copper.
Average Coverage
For a mass estimate, use retained copper coverage rather than 100% unless the layer is effectively a solid plane.
Layer Count
Apply plating only to the plated outer-layer count. Do not add outer-layer plating thickness to every internal copper layer.
ENGINEERING BOUNDARY
What the Converter Includes and What Fabrication Must Confirm
Included in the Converter
- oz/ft², µm, mm, mil, and g/m² conversion
- Industry nominal and density-derived bases
- Base foil plus optional plating thickness
- Equivalent finished copper weight
- Area, coverage, layer-count, volume, and mass estimate
Confirm with the Fabricator
- Foil area-weight tolerance and supplier certification
- Finished outer-copper definition on the fabrication drawing
- Pattern-plating distribution and minimum surface copper
- Etch reduction, sidewall profile, and local copper density
- Heavy-copper design rules, spacing, and manufacturability
SPECIFY THE CONTROLLED PROPERTY
State whether the requirement is starting foil weight, nominal thickness, or finished outer copper after plating.
NEXT ENGINEERING CHECKS
Related PCB, Power, Thermal, and Platform Calculators
Continue from copper specification into current capacity, route loss, via design, controlled impedance, thermal screening, and system-level planning.
PCB Design Tools
Power and Thermal Tools
Platform Planning Tools
PCB COPPER WEIGHT FAQ
Practical Questions About Copper Weight and Finished Thickness
Use the converter for specification alignment, then confirm fabrication tolerances and plating requirements with the PCB manufacturer.
The answers below focus on 1 oz copper, nominal thickness, plated outer layers, heavy copper, and mass estimates.
Discuss a PCB Copper RequirementHow thick is 1 oz PCB copper?
The common PCB nominal conversion is 35 µm, 0.035 mm, or about 1.378 mil. A density-derived physical conversion is slightly lower, so the selected basis should be stated.
Why do some references show 34 µm and others show 35 µm?
About 34.06 µm follows from copper density and the exact mass-per-area definition. The PCB industry commonly rounds the nominal drawing and stackup value to 35 µm per ounce.
Is finished outer copper the same as base foil weight?
Not always. Outer layers can receive additional deposited copper during through-hole plating, so finished thickness may exceed the starting foil thickness.
How do I convert copper thickness in mils to ounces?
Select Imperial units, start from Copper Thickness, and enter the measured mil value. The result shows the equivalent oz/ft² using the selected nominal or density-derived basis.
Can this converter estimate total copper mass on a PCB?
Yes. Enter board area, average copper coverage, copper-bearing layer count, plated-layer count, and plating thickness. The result remains an estimate because real coverage varies by layer.
Does heavier copper automatically mean higher current capacity?
Heavier copper increases conductor cross-section, but current capacity also depends on trace width, temperature rise, layer environment, airflow, copper spreading, and layout geometry.