How It Works

Wallpaper is usually applied as vertical strips (often called drops). The calculator estimates how many strips your room needs based on the room perimeter and the roll width. Next, it estimates how many full-length strips can be cut from one roll based on roll length and your required strip length (wall height plus trimming, plus any pattern repeat adjustments). Finally, it converts strips into rolls and adds an allowance so you can account for offcuts, mistakes, and future repairs.

What You Enter

• Room size: Use a single perimeter value for quick input or provide a list of wall widths for irregular rooms.
• Wall height: Height determines the strip length and strongly affects how many strips you can cut per roll.
• Openings: Add doors and windows so the estimate reflects the reduced coverage area in most rooms.
• Roll specifications: Enter the roll width and roll length from the manufacturer label or product page.
• Pattern repeat: If the wallpaper has a repeat, the tool increases strip length to represent pattern alignment waste.
• Allowances: Trimming allowance and a percentage margin help ensure you do not run short.

Key Features

Perimeter Mode and Wall-List Mode

If your room is a simple rectangle, entering one perimeter number is fastest. If your room has recesses, a bay area, or partial walls, wall-list mode lets you paste each measured wall width (one per line or separated by commas). The calculator sums the walls into a perimeter so the estimate remains consistent, even when the geometry is awkward.

Door and Window Handling Without Complex Wall Plans

Subtracting openings is useful, but real rooms rarely allow you to remove an exact number of full wallpaper strips. Instead of forcing wall-by-wall layouts, the tool subtracts opening area and converts it into an equivalent reduction in strip count. This produces a realistic estimate for most rooms while keeping the input fast.

Pattern Repeat and Match Type Options

Large repeats can significantly reduce yield because strips must be cut longer to align the design across seams. Choose a match type that reflects the product guidance: random/no match for wallpapers with no alignment requirement, straight match for patterns that align at the same height, and offset/half-drop for patterns that shift between adjacent strips. The calculator adjusts strip length accordingly so the roll count is not underestimated.

Trimming and Safety Margin Controls

A trimming allowance gives you extra length at the top and bottom for clean edges and for small ceiling or skirting irregularities. The extra margin percentage then increases the roll count to cover mistakes, damaged strips, and unexpected waste. If you prefer, you can also include a spare roll, which is especially useful when you want to keep all rolls from the same dye lot.

Copy-Ready Order Summary

The output includes a clear “rolls to buy” number and a copy-ready summary of the assumptions: strip count, strips per roll, adjusted strip length, and the allowance settings. This makes it easy to share the estimate with a contractor, store, or family member and to reproduce the calculation later.

Use Cases

• Room renovations: Estimate materials early so you can order on time and keep installation moving.
• Budgeting: Compare wallpaper options by changing roll size and repeat to see how the total rolls (and cost) change.
• Feature walls: Enter only the wall widths you plan to cover and set openings to zero if the wall is clear.
• Contractor quotes: Produce consistent roll estimates for client proposals or purchasing lists.
• Patterned wallpaper planning: Understand how repeats and match types affect waste before buying.
• Repairs and touch-ups: Add a spare roll so you can patch damage later without hunting for discontinued stock.

In practice, many people run two estimates: one early estimate for budgeting, and a final estimate after selecting the exact wallpaper so roll dimensions and repeat can be copied from the manufacturer specification.

Optimization Tips

Measure Height in Multiple Spots

Wall height is the biggest driver of strips-per-roll yield. Measure at two or three points, especially in older buildings, and use the largest value. A few centimeters can change whether you get three strips per roll or only two, which changes the total rolls you must buy.

Use Exact Roll Specs and Repeat Values

Not every wallpaper uses the same roll length or width. Some brands sell “double rolls” or wider European rolls, and repeats may be listed in centimeters or millimeters. Copy the label values exactly and pick the match type that matches the hanging instructions.

Order All Rolls at Once

Wallpaper can vary slightly between production batches. Buying all rolls in one order improves the chance they share the same dye lot, helping color and sheen remain consistent across seams. This is especially important for large walls and bright natural light.

FAQ