Understanding your result
The headline is the number of tack strip pieces, with the run in feet and the bundles in the line beneath it. The stats give the run, the bundles and the doorway edges; the table walks from the perimeter, less the doorways, to the run, the pieces and the bundles, with the concrete nails if the subfloor is concrete.
The perimeter is the length of every wall the carpet meets, closets included. The doorways come out of it because the carpet ends there in a metal edge or a transition, not in tack strip. The run divided by the piece length, plus 10% for the cuts at inside and outside corners and around door frames, gives the pieces, and the pieces give the bundles.
Doorway edge strips are listed as one per doorway so they make the shopping list; their type depends on the floor on the other side, which the thresholds and transitions calculator works out. For the perimeter of an L-shaped or irregular room, the perimeter calculator adds the walls up. The carpet that the strip holds is on the carpet calculator.
How we calculate this
The 10% covers the pieces cut to fit corners and the short lengths around door casings and radiator pipes. Each 4 ft piece of the concrete type is usually nailed at three or four points; the calculator plans on three. The guide to measuring odd rooms covers adding up the walls of a room that is not a rectangle, and the carpet roll guide explains how the strip and the gully fit into the whole carpet installation.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Piece length | 4 ft (1.2 m) | Standard tack strip piece |
| Bundle | 50 pieces | Common bundle; 100-piece bundles exist |
| Corner allowance | 10% | Installer rule of thumb |
| Door width | 3 ft (0.9 m) | A standard interior door with its casing |
| Wall gap | about 2/3 of carpet thickness | Carpet and Rug Institute CRI 105 installation guidance |
| Concrete fixing | about 3 masonry nails per piece, or glue | Manufacturer instructions |
Assumptions last reviewed October 8, 2026.
The calculator does not count stair tack strip, which goes on every tread and riser; the stair carpet calculator lists it. It does not distinguish the pin heights made for thick and thin carpet, which you choose by the carpet, and it does not count the carpet edge strips by material, only by doorway.
Two worked examples
A 14 × 13 ft bedroom with two doors
Wood subfloor, 4 ft pieces, bundles of 50.
- Perimeter: 2 × (14 + 13) = 54 ft; less 2 × 3 ft doors = 48 ft
- Pieces: 48 ÷ 4 × 1.1 = 13.2, rounded up to 14 pieces, one bundle
- Doorway edge strips: 2
A bundle of 50 does three rooms like this. Buy one and keep the rest for the next room; tack strip keeps indefinitely.
A basement with 148 ft of wall and four doors
Concrete slab, perimeter typed directly.
- Run: 148 − 4 × 3 = 136 ft
- Pieces: 136 ÷ 4 × 1.1 = 37.4, rounded up to 38 pieces, one bundle
- Concrete nails: about 114; edge strips 4
If the slab has a heated floor or a vapor barrier, the strip is glued with construction adhesive instead of nailed; a nail through a heating cable is an expensive mistake.
Where to find your inputs
Perimeter. Measure every wall the carpet will meet, including the inside of closets. The perimeter calculator adds them up.
Doorways. Count the openings where the carpet stops at another floor or a threshold.
Piece and bundle. On the bundle label: 4 ft pieces, 50 or 100 per bundle.
Subfloor. Wood or concrete; buy the matching type of strip.
Common mistakes
- Pins pointing the wrong way. They must angle toward the wall to grip the stretched carpet.
- Strip tight to the wall. The gully is needed to tuck the carpet. Leave about 3/8 in.
- Nailing a heated slab. Glue the strip on radiant floors and over vapor barriers.
- Tack strip across a doorway. Use a metal edge or transition there.
- Wood strip on concrete. The nails bend. Use the concrete type with hardened nails.
- Forgetting the closets. Their walls need strip too.
Questions people ask
- How much tack strip do I need for a room?
- The room's perimeter less the doorway widths, plus about 10% for corners and cuts. A 14 × 13 ft room has 54 ft of wall; less two 3 ft doors that is 48 ft, which is 14 pieces of 4 ft strip with the allowance. Tack strip comes in bundles of 50 or 100 pieces.
- How long is a piece of tack strip?
- Standard tack strip is sold in 4 ft (1.2 m) pieces, in bundles of 50 or 100, which is 200 or 400 ft. It is about 1 inch wide, with two or three rows of angled pins.
- How far from the wall does tack strip go?
- About two-thirds of the carpet's thickness, which is roughly 3/8 inch for most residential carpet, with the pins pointing toward the wall. The gap is the gully into which the carpet edge is tucked.
- Can tack strip be nailed into concrete?
- Yes, with the concrete type of strip, which has hardened masonry nails, or it can be glued with construction adhesive. Heated slabs and slabs over a vapor barrier must never be nailed; glue only.
- What goes at doorways instead of tack strip?
- A metal carpet edge strip, a Z-bar or a transition to the adjacent floor, which grips the carpet edge and protects it. The thresholds and transitions calculator counts them by doorway and material.
- Is tack strip used on stairs?
- Yes, at the back of each tread and the bottom of each riser, usually two pieces per step. The stair carpet calculator lists it with the carpet and pad for the flight.