How long should a nail be?

As a general rule, the nail should be 2.5 to 3 times the thickness of the piece you are fixing. This ensures enough penetration into the receiving piece for a secure hold. For example, fixing 18mm board at 2.5x gives a 45mm minimum, which rounds up to the nearest standard 50mm nail (45mm is not a stocked UK length).

When should I use panel pins vs round wire nails?

Panel pins (1.25-1.6mm gauge) are for trim, mouldings, and cabinetry where you want to conceal the head. Round wire nails (2.65-3.35mm) are for structural work like framing where strength matters more than appearance.

Do I need pilot holes for nails?

Pilot holes are recommended when nailing near edges or ends of timber, when using hardwood, or when using large gauge nails. Drill at about 80% of the nail diameter. For softwood framing, pilot holes are generally not needed.

WoodCalcs.uk

Nail Size Calculator — Select the Right Nail

Select the right nail type, gauge, and length for your woodworking task based on material thickness.

Task TypeDetermines nail type and gauge: framing = round wire nail (3.35mm), trim/panelling = lost-head pin/panel pin (1.6mm), cabinet = brad (1.25mm), flooring = ring-shank floor brad (2.65mm).

Material Thickness

Thickness of the piece being nailed

Number of Nails

Nails per Box (optional)

Price per Box (optional)

Enter your supplier price for a cost estimate

How We Calculate This

This calculator selects the appropriate nail type and size based on your woodworking task and the thickness of the material being fixed.

The rule

Nail length = Material thickness x 2.5 (minimum)

The result is rounded up to the nearest standard UK nail length. The nail type and gauge are selected based on the task category.

Pilot holes

For finish nails and panel pins, a pilot hole of approximately 80% of the nail diameter helps prevent splitting, especially in hardwood.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.