This timber fastener spacing calculator works out how many nails, screws or bolts you need — and the correct spacing — for any timber connection. It doubles as a timber screw spacing calculator and a general timber connection calculator for decking, framing and structural joints.
This timber fastener spacing calculator tells you how many nails, screws or bolts a timber connection needs and how far apart to space them. Whether you use it as a timber screw spacing calculator for decking and framing, or as a general timber connection calculator for structural joints, it also works out the correct edge and end distances so the timber doesn't split. It is built for UK DIYers, carpenters and builders working in either millimetres or inches.
Typical on-centre spacing and minimum edge/end distances for common timber fixings. Use these as a starting point, then check the fastener manufacturer's data and your structural drawings.
| Fastener | Typical spacing | Edge distance | End distance |
|---|---|---|---|
| Nails | 150 mm (6") | 38 mm (1.5") | 50 mm (2") |
| Screws | 200 mm (8") | 50 mm (2") | 75 mm (3") |
| Bolts / coach screws | 300 mm (12"), min 4× dia | 75 mm (3"), min 1.5× dia | 125 mm (5"), min 7× dia |
Sawn and regularised carcassing timber (CLS and C16/C24) comes in these nominal sizes — handy when planning where fixings land:
| Nominal size | Typical use |
|---|---|
| 38 × 63 mm (2×3) | Stud walls, noggins, light framing |
| 38 × 89 mm (2×4) | Stud walls, plates, decking frames |
| 47 × 100 mm | Floor joists, rafters (small spans) |
| 47 × 150/200 mm | Floor and roof joists, deck joists |
Say you are fixing a 2.4 m (2400 mm) deck board run with screws in a single row. With a 75 mm end distance at each end, the usable run is 2400 − (2 × 75) = 2250 mm. At 200 mm spacing that is about 11 gaps, so you will need 12 screws along the board. Multiply by the number of boards and add a few spare, and you have your total. This is exactly what the calculator does automatically.
Working on a deck or a partition wall? Try our decking screw calculator, stud spacing calculator and joist calculator to plan the whole job.
Yes. This timber fastener spacing calculator works as a timber screw spacing calculator, a nail spacing calculator and a bolt spacing calculator — just choose the fastener type. It gives the number of fixings, the on-centre spacing and the correct edge and end distances for any timber connection.
For structural connections, 200 mm (8 inches) on centre is a common starting point. Always check the fastener manufacturer's recommendations and, for structural work, your design details for the exact requirement based on timber grade, fastener diameter and load.
Edge distance is measured perpendicular to the grain, from the fastener to the nearest edge. End distance is measured parallel to the grain, from the fastener to the end of the timber. Both minimums stop the timber splitting.
Double-row staggered patterns are used for wider timber connections, laminated beams and when a single row does not provide enough capacity. Staggering the fixings reduces the risk of splitting along the grain.
Bolt spacing depends on bolt diameter. Minimum spacing is typically 4× the bolt diameter along the row, with 3× minimum between rows. End distance should be at least 7× diameter for tension loads. Always verify against engineering tables or codes.
Learn the essentials of timber connections: types, strengths, spacing, plus practical examples and FAQs. Get tips and use our timber connection calculator.
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