Understanding your result
The headline is the number of spools, and the sub-line gives the border needed and the cost. The three figures show the border needed, the leftover after the last spool and the cost.
The table shows the perimeter or run, the length skipped if any, the border to hang, the allowance and the corner extra, the border needed, the spools, the leftover and the cost. The leftover is usually several feet, which is the right amount to keep for a repair; borders are discontinued faster than wallpapers.
Borders often go with paint or paper below them. The two-tone wall calculator handles a border at chair-rail height between two paint colours; the roll calculator sizes the paper if the border sits above a papered wall; and the paste calculator covers the adhesive.
How we calculate this
The allowance covers the pattern matching at joins between spools, where each new spool starts at the next matching point in the design; 10% is a round figure for a border with a moderate repeat. The corner extra is a foot per corner for the overlap and pattern alignment as the border turns. A rectangular room has four corners; every bay, chimney breast or alcove adds two. The wallpaper roll guide explains the pattern repeat that drives the allowance, and the two-tone walls guide covers choosing the chair-rail height.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Spool length | 15 ft (5 yd), 5 m in metric | Common US and European border spool lengths |
| Allowance | 10% | A round figure for matching the pattern at joins |
| Corner extra | 1 ft (0.3 m) per corner | Site estimate for the turn and alignment |
| Price | $20 a spool | A typical 2025 US price |
Assumptions last reviewed October 8, 2026.
The calculator does not model borders with a very long repeat, where the allowance should be raised, borders mitred around windows or doors as frames (measure each frame’s perimeter as a run), or the adhesive quantity, which is small.
Two worked examples
A bedroom border at the ceiling
12 × 10 ft room, four corners, 15 ft spools at $20, 10% allowance.
- Perimeter: 2 × (12 + 10) = 44 ft
- Needed: 44 × 1.10 + 4 × 1 = 52.4 ft
- Spools: ⌈52.4 ÷ 15⌉ = 4, $80, 7.6 ft left over
In metric, the same room with 5 m spools needs 15.74 m of border, four spools again.
The same room at chair-rail height
A doorway and two windows the border meets, 9 ft to skip.
- To hang: 44 − 9 = 35 ft
- Needed: 35 × 1.10 + 4 = 42.5 ft
- Spools: 3, $60, 2.5 ft over
A straight 30 ft run with no corners and no allowance, by comparison, is exactly two spools with nothing to spare, which is why the allowance is there.
Where to find your inputs
Perimeter or run. The room’s length and width, or the measured run for part of a room.
Corners. Count inside and outside corners the border turns.
Length to skip. At chair-rail height, the widths of the doorways and windows the border meets.
Spool length and price. On the label.
Common mistakes
- Buying for the perimeter exactly. Joins and corners need extra.
- Ordinary paste over vinyl. Use a border adhesive.
- Starting at the most visible corner. The last join never matches perfectly.
- Subtracting doors for a ceiling border. It runs above them.
- Mixing batches. Check the batch number on every spool.
- Forgetting alcove corners. Each alcove adds two.
Questions people ask
- How many rolls of border do I need for a 12 × 10 room?
- The perimeter is 44 ft. With 10% for matching the pattern at joins and a foot at each of the four corners, that is 52.4 ft of border, which is four 15 ft spools with about 7.6 ft left over.
- How long is a spool of wallpaper border?
- Most US borders come in 5-yard (15 ft) spools; some in 7 or 10 yards. European borders are usually 5 m. The spool length is on the label, and the calculator takes any value.
- Why add extra at the corners?
- Because a border is turned around inside corners with a small overlap and cut to keep the pattern aligned on the next wall. A foot per corner covers that comfortably; the leftover is rarely wasted because the last join needs it too.
- Do I subtract doors and windows?
- At the ceiling, no, because the border runs above them. At chair-rail height, yes, the width of each doorway and any window the border meets, which you enter as the length to skip.
- What paste do I use for a border?
- On a painted wall, ordinary wallpaper paste or the border's own pre-paste. Over vinyl wallpaper, a vinyl-to-vinyl or border adhesive, because ordinary paste will not grip the vinyl face. A small tub does a room.
- Where should the border start?
- In the least visible corner, usually behind the door, because the last join, where the pattern almost never matches perfectly, ends up there.