Aluminium foil does not have one standard thickness. The European Aluminium Foil Association describes foil as ranging from about 0.006 mm to an upper limit of 0.2 mm—approximately 6–200 µm. That is a product-category range, not a statement that every grade, finish or application is supplied throughout it. For procurement, specify nominal thickness, tolerance and the required performance together.
Read Microns and Millimetres Correctly
One micrometre (µm), often called a micron, equals 0.001 mm. A quotation for 20 µm foil therefore means 0.020 mm, not 0.20 mm. Avoid relying on informal labels such as “standard,” “heavy duty” or “extra thick”: these labels do not define a universal engineering thickness.
| Thickness in µm | Thickness in mm |
|---|---|
| 6 | 0.006 |
| 10 | 0.010 |
| 20 | 0.020 |
| 50 | 0.050 |
| 100 | 0.100 |
| 200 | 0.200 |
These conversions are examples, not recommended minimums or a stock list. A foil laminate may also have a total thickness different from its aluminium layer. Ask whether a reported value describes bare metal, coated foil or the complete multilayer construction.
How to Measure Foil Thickness
Direct measurement
Use an instrument and method suitable for thin flexible material. Resolution alone does not establish accuracy: contact pressure, calibration, surface cleanliness and wrinkles can affect a reading. Define where and how many measurements are required, and compare results with the ordered tolerance rather than a rounded label.
Mass-per-area calculation
For clean, uncoated foil, average thickness can be estimated from mass, area and material density. With mass m in grams, area A in square centimetres and density ρ in g/cm³, thickness in centimetres is m/(A × ρ). Multiply by 10,000 to express that result in micrometres. This estimates an average over the sample; it does not reveal local thin spots.
A coating, adhesive or backing contributes mass. Do not use total laminate mass as aluminium mass in the calculation. Use the agreed alloy density and measurement procedure when the result is for acceptance.
Choose Thickness by Performance, Not a Generic Use Label
| Application concern | What to define |
|---|---|
| Packaging barrier | Pinhole criteria, laminate construction, seals and required barrier performance. |
| Handling and converting | Temper, tensile behavior, elongation, web handling and slit-edge quality. |
| Forming or wrapping | Required flexibility, formed geometry and resistance to tearing in the actual process. |
| Thermal exposure | Actual temperature and construction; thickness does not create a new melting point. |
| Electrical application | Alloy/purity, surface condition, dimensions and the component-specific specification. |
Thicker foil is not automatically the right answer. Performance can depend on temper, defects, supporting layers and converting conditions as much as nominal gauge. Food, pharmaceutical and battery applications require their own qualification; a thickness value alone does not establish suitability or regulatory compliance.
Keep Standard Names and Scope Accurate
ASTM B479 concerns annealed aluminium foil for flexible-barrier, food-contact and other applications; it is not the capacitor-foil specification. ASTM B373 concerns capacitor foil. If EN 546 is specified, identify the relevant part and edition. The order must match the scope of the chosen standard and any additional application requirements.
Do not assume that citing several standards proves a particular roll complies with all of them. Agree the alloy, temper, tolerance, inspection method and documents before production. A supplier’s general capability statement is different from a certificate for a supplied lot.
A Useful Foil Inquiry Checklist
- Alloy or purity requirement and temper.
- Nominal aluminium thickness and tolerance, clearly distinguished from total laminate thickness.
- Width, length or roll weight, core size and winding requirements.
- Surface, coating, cleanliness and pinhole criteria as applicable.
- Intended converting process, quantity, inspection documents and destination.
If replacing an existing foil, include its specification or an approved reference sample and describe the problem being solved. That supports a meaningful comparison instead of choosing only by the lowest unit price.
References: European Aluminium Foil Association; ASTM—Foil Specification Listings.
Post time: Jul-21-2025