P40 sandpaper
425 µm grain
P40 (FEPA) · about 36 grit (CAMI) · 0.425 mm average particle
What P40 is for
Stripping paint and levelling rough timber. It removes material fast and leaves scratches that take three finer grits to remove, so it is a starting point rather than a choice.
The two scales
| FEPA (European) | P40 |
| CAMI (American) | about 36 |
| Average grain | 425 µm |
| Scales agree here? | Yes, near enough to substitute |
Nearby grits
| FEPA | CAMI | Grain | Typically |
|---|---|---|---|
| P40 | 36 | 425 µm | Stripping paint and levelling rough timber |
| P60 | 60 | 269 µm | Heavy shaping and taking off old finish |
| P80 | 80 | 201 µm | The usual first grit on bare timber |
Frequently asked questions
Is P40 the same as 40 grit?
Close enough to treat as the same. Below about P180 the European and American scales agree; the divergence starts above it.
What grain size is P40?
An average grain of 425 µm — 0.425 mm. That figure is what the P number is defined by, which is why it is the reliable way to compare across scales.
What is P40 used for?
Stripping paint and levelling rough timber. It removes material fast and leaves scratches that take three finer grits to remove, so it is a starting point rather than a choice.
Is P40 at the end of the range?
This is the coarsest grit in common use.