Nailer › Nail gun nail sizes and gauges
Nail gun nail sizes and gauges
Nail guns only take the nails they were designed for. Here is how to read sizes and pick the right ones.
Length, gauge and head
Three things describe a nail: length (in mm in the UK), gauge (thickness) and head type. With gauge, a bigger number usually means a thinner nail, so a 16 gauge nail is thicker than an 18 gauge nail. Gauge systems vary, so always check your tool's manual.
Typical sizes by tool
| Tool | Typical nails | Source / note |
|---|---|---|
| Framing (first fix) | 50 mm to 90 mm, clipped-head | One UK hire firm's figure |
| Finish (second fix) | 16 gauge, 15 mm to 64 mm | One UK hire firm's figure |
| Brad nailer | Thinner than finish nails, small head | Check manual for gauge and length range |
| Pin nailer | Very fine, headless pins | Check manual |
| Roofing | Short, wide-headed coil nails | Check manual |
Ranges differ between makers and models, and some finish nailers are rated for heavier or lighter gauges than the 16 gauge example. We only give figures we found in a published source, so check your own tool for the exact range.
Choosing nail length
A common rule of thumb is that a nail should go through the first piece and penetrate the second by about twice the thickness of the first, or more. For example, fixing 18 mm skirting to a wall needs a nail long enough to bite into the masonry or stud behind it. In structural work, building regulations or a designer may specify nail type and spacing, and you should follow that.
Head types
- Full round head: more holding power and often used where the building rules call for it.
- Clipped or offset head: allows more nails per strip. One source notes clipped heads may not be allowed in some areas, so check your local regulations before buying.
- Headless or small head: for trim, easily filled.
Coatings and materials
Nails come bright (plain), galvanised or stainless. Outdoor work such as fences and decking needs corrosion-resistant nails. Some timber treatments and oak corrode plain steel, so choose stainless or the type recommended by the timber supplier.
Why gauge matters for the finish
A thicker nail holds better but is more likely to split thin or dry timber, especially close to an edge. A thinner nail splits less but holds less. That is why finish and brad nailers exist: they trade holding power for a neater result. Pre-drill or move away from the edge if you see splitting.
Collation and compatibility
Nails for guns are joined in strips or coils, and the angle and type must match the tool. A 21 degree plastic-strip nail will not fit a 34 degree tool. See collation angles.
Buying checklist
- Read the tool's label or manual for gauge, length range and collation angle.
- Choose length for the material thickness and the depth of hold.
- Pick coating for indoor or outdoor use.
- Buy a small quantity first and test on offcuts.
Related: types of nail gun and first fix vs second fix.
This is general information, not a substitute for the manufacturer's manual or training. Always check the nail sizes and collation your own tool accepts.
Frequently asked questions
Does a bigger gauge number mean a thicker nail?
Generally no, a bigger gauge number usually means a thinner nail. Check the tool's manual.
What nail length for framing?
One UK hire firm gives 50 mm to 90 mm for first fix nailers. Check your tool.
Can I use any nails in my nail gun?
No. Use the length, gauge and collation your tool specifies.
What nails for outdoor work?
Use galvanised or stainless nails for fences and decking, and check timber supplier advice.