The short answer
1/2in (12mm) narrow-crown staples, 18–20 gauge
That covers most runner-and-underlay combinations on softwood or engineered treads. Go to 9/16in or 5/8in for thick runners or where you are also fixing underlay in the same pass.
Choosing by build-up
| Situation | Staple length |
|---|---|
| Thin flatweave runner, no underlay | 3/8in (10mm) |
| Standard runner + underlay | 1/2in (12mm) |
| Thick wool runner + underlay | 9/16in–5/8in (14–16mm) |
| Runner over existing low-pile carpet | 5/8in–3/4in (16–19mm) |
Crown width and gauge
Use narrow-crown staples, around 1/4in. A wide crown grips more but is visible in the pile and can crush a low-pile runner. 18 or 20 gauge is the sweet spot — fine enough to disappear, strong enough to hold.
Spacing
- Every 3–4in across the crease at the back of each tread.
- Two extra staples just under the nosing on each side of the runner.
- Closer spacing — every 2in — on the top and bottom steps, which take the most stress.
- Angle staples slightly into the timber rather than straight down.
Manual, electric or pneumatic?
| Stapler | Verdict |
|---|---|
| Heavy-duty manual | Fine for softwood; hard work over 13 steps |
| Electric | Best value for DIY; consistent depth |
| Pneumatic | What fitters use; fastest and most controlled |
On old hardwood treads, test on an off-cut first. If staples sit proud, the gun lacks power for that timber and you will need pneumatic or a shorter, finer staple.
Whatever you decide, get the numbers first: the stair runner calculator doubles as a stair runner length calculator, adding nosing wrap, landings, winders, pattern repeat and waste so you order the right length the first time.
Frequently asked questions
What size staples for a stair runner?
1/2in (12mm) narrow-crown staples in 18–20 gauge suit most runner and underlay combinations. Use 3/8in for thin runners with no underlay and up to 5/8in for thick wool runners.
How far apart should stair runner staples be?
Every 3–4in along the crease at the back of each tread, plus a couple under the nosing on each side. Tighten to every 2in on the top and bottom steps.
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Plan your runner install