How does the pattern repeat change how many rolls of wallpaper I need?

BuildBatch rounds each drop up to a whole number of repeats, so that every drop starts at the same point of the pattern. In a 4.2 m × 3.6 m room with walls 2.4 m high, a 53 cm repeat turns a 2.5 m drop into 2.65 m, so a 10.05 m roll gives 3 drops instead of 4 and the room needs 10 rolls instead of 8.

Does a half-drop match use more wallpaper than a straight match?

In the planner's count it adds half a repeat to every drop. With a 53 cm repeat that makes 2.915 m against 2.65 m, and both give 3 drops a roll, so both need 10 rolls. With a 50 cm repeat the straight match needs 8 rolls and the half drop 10.

What do I enter for a plain or textured wallpaper?

Choose a free match and leave the repeat out. A free match uses no repeat: even if you type one, the planner ignores it and cuts 2.5 m drops, which is 8 rolls in the 4.2 m × 3.6 m room.

I typed the repeat and the rolls did not change. Why?

In the form the match starts at free match, and a free match ignores the repeat. Choose straight or half drop as well: in the example room a 53 cm repeat then gives 10 rolls instead of 8.

Wallpaper pattern repeat: straight match, half drop and free match

The repeat printed on the roll’s label sets how long each drop is cut. BuildBatch rounds the drop up to a whole number of repeats for a straight match, adds half a repeat on top for a half drop, and does neither for a free match. In a 4.2 m × 3.6 m room with walls 2.4 m high, the example roll, 53 cm × 10.05 m, takes 8 rolls with a free match and 10 with a 53 cm repeat, straight or half drop.

What each match does to the drop

BuildBatch tells the three matches apart. A drop is one full-height length of paper.

Match	The planner’s description	What it does to the drop
Free match	No pattern to line up, or a plain or textured paper	Nothing: the drop is the height plus 10 cm, and any repeat typed in is ignored
Straight match	The pattern lines up straight across from drop to drop	The height plus 10 cm, rounded up to a whole number of repeats
Half-drop match	Every other drop is offset by half a repeat	The same, plus half a repeat

The count is a simple one. It adds the half repeat to the length of every drop, and it does not plan how pieces are cut from the roll or whether an offcut can be used. The label and the maker’s instructions say the rest.

The sum

Cut length = the wall’s height + 10 cm, for trimming at the top and the bottom.
Drop length = the cut length, rounded up to whole repeats for a straight or half-drop match, plus half a repeat for a half drop.
Drops per roll = the roll’s length ÷ the drop length, rounded down.
Drops per wall = the wall’s width ÷ the roll’s width, rounded up.
Rolls = all the drops ÷ drops per roll, rounded up.

The same room is worked step by step in how many rolls of wallpaper do I need?, and the figures here match it.

One room, three repeats

A room 4.2 m × 3.6 m with walls 2.4 m high, papered with the example roll, 53 cm wide and 10.05 m long. The walls take 8 + 7 + 8 + 7 = 30 drops, and each is cut at 2.4 m + 10 cm = 2.5 m before the pattern is allowed for. The roll is a generic example, not a product, and 32, 53 and 64 cm are example repeats, not the repeats of any paper.

Match	Repeat	Drop length	Drops per roll	Rolls	Spare drops
Free	none	2.5 m	4	8	2
Straight	32 cm	2.56 m	3	10	0
Straight	53 cm	2.65 m	3	10	0
Straight	64 cm	2.56 m	3	10	0
Half drop	32 cm	2.72 m	3	10	0
Half drop	53 cm	2.915 m	3	10	0
Half drop	64 cm	2.88 m	3	10	0

A 53 cm repeat. 2.5 m is 4.7 repeats, rounded up to 5, which is 2.65 m. A half drop adds half a repeat, 26.5 cm, to make 2.915 m.
Why the rolls stop at 10. A 10.05 m roll gives 4 drops only if the drop is no longer than 2.5125 m. Every repeat in the table takes the drop past that, so each roll gives 3 and the room needs 10 rolls whichever repeat or match.
Where the match changes the count. A 50 cm repeat fits the 2.5 m cut length exactly, five times. As a straight match the drop stays 2.5 m, a roll gives 4 and the room takes 8 rolls. As a half drop it becomes 2.75 m, a roll gives 3 and the room takes 10.
No spare drop. Where 10 rolls leave none, the list warns that one mis-cut leaves you a roll short.

What goes in from the label

The planner needs four figures from the roll’s label: the width, the length, the repeat and the match. Without them it starts with the example roll and a free match, and each line says they are generic examples.

A free match with a repeat typed in. The repeat is ignored. In the form the match starts at free match, so choose the label’s match as well as typing the repeat.
A repeat with no match at all. In a list link or a call to the assistant interface, the planner takes a straight match.
A repeat of 0. The paper is counted as plain.

Do it with BuildBatch

Open the wallpaper calculator, type the room and copy the width, length, repeat and match from the roll’s label. You get the rolls and every other line, each marked Need or Check first, with the reason it is there. The room refresh planner counts the rolls, the paste and the tools for the whole room.

What this guide does not cover

How a pattern is lined up and hung, which the paper’s instructions give. A match the planner does not list: check the label and the maker’s instructions. Offcuts reused to make another drop. Doors and windows, which the planner does not take off wallpaper: see how many rolls of wallpaper do I need? Paste, lining paper and preparing the walls.