Craft Quantities
Plan & Takeoffs

Renovation & Construction

Tile Backer Board Calculator

Count cement backer boards, screws and joint tape for a tiled wet area.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
Who is doing the work?

Waste is set to 15% by hand. Pick a tier above to replace it, or keep your own figure.

Wall or floor area needing backer board.

The area to be boarded, measured to where the boarding stops rather than to the room's dimensions — a wet area board that runs 150 mm past the shower enclosure stops there, and the rest of the wall is plasterboard. Deduct openings over about a square metre; below that the cutting waste eats the saving. Backer board is a substrate and not a waterproofing layer on its own, so the area that needs tanking may be larger than the area that needs boarding.

Sheet size you are buying.

Smaller boards are easier to handle in a bathroom and produce more joints to tape. On a large floor, larger sheets are worth the handling.

Allowance for cuts around openings and fittings.

15% is realistic in a bathroom, where every board meets a window, a door or a fitting. On a plain floor 10% is enough.

Boards required

18 boards

Medium confidence

Fixing counts assume 200 mm (8 in) centres on a typical board. Follow the manufacturer's pattern, which varies between products and between wall and floor use.

Board coverage
10.33 sq ft
Area with waste
184 sq ft
Backer board screws
305 screws
Alkali-resistant mesh tape
190.29 ft
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Fastener spacing 200 mm (8 in) on centre through the field and at edges — manufacturer installation instructions and TCNA Handbook
  • Joints taped with alkali-resistant mesh tape and set in the same mortar used to bed the tile

Inputs used

Area to board
160 sq ft
Board size
1200 × 800 mm (10.3 sq ft)
Cutting waste (%)
15

Intermediate steps

Board coverage
10.33 sq ft
Area with waste
184 sq ft
Backer board screws
305 screws
Alkali-resistant mesh tape
190.29 ft
Final result18 boards

Confidence note: Fixing counts assume 200 mm (8 in) centres on a typical board. Follow the manufacturer's pattern, which varies between products and between wall and floor use.

What this calculation does not cover

  • Backer board is not a waterproofing layer on its own. A wet area needs a membrane or a liquid-applied system over it, which is a separate material.
  • Floor installations must be bedded in mortar over a sound deck, not simply screwed down.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

12.65 ft3.86 m12.65 ft3.86 mequivalent area160 sq ft14.86 m²5 ft1 m

Part of bigger jobs

This trade is one line of several job takeoffs. Run the whole job and every other trade comes back with it, off the same measurements.

Or plan the space itself: measure it once, doors and windows included, and this figure comes back worked out on that space, with what goes with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations2
  1. Fastener spacing 200 mm (8 in) on centre through the field and at edges — manufacturer installation instructions and TCNA Handbook
  2. Joints taped with alkali-resistant mesh tape and set in the same mortar used to bed the tile
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To fix the tile backer board. Generic types, no brands, no prices.

Protection this work requires

  • Cutting or grinding concrete, masonry, screed, tile or fibre-cement board releases respirable silica: cut wet or extract at the tool, and wear a P2/N95 respirator at minimum — a nuisance dust mask does not filter it.
  • Boards, blocks and bagged material cause most lasting back injuries on small sites: two people or a lifter for full sheets, and never a bag on one shoulder up a ladder.
  • Knives cause more site injuries than any power tool: cut away from your body, change blades often, and wear cut-resistant gloves to EN 388 level C for repeated cutting.
Show the 6 tools this job needs

Essential

  • Impact driver

  • Tape measure

  • Utility knife

Recommended

  • Hole saw set

  • Jigsaw

  • Notched trowel

Also needed as materials: impact driver bits, jigsaw blades, replacement blades.

what each tiling tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Still deciding? Crack Isolation Membrane vs Backer Board — the factors that actually differ, with no invented prices.

Already have some? How much shower wall will my backer boards cover?

Worked example: Bathroom gutted and retiled — step 4 of 9

The data behind it: Production rates by operation

How to calculate tile backer board in 4 steps

  1. Area to boardWall or floor area needing backer board.
  2. Board sizeSheet size you are buying.
  3. Cutting waste (%)Allowance for cuts around openings and fittings.
  4. Boards requiredThe tool computes the boards required from those figures and shows the formula, its sources, and a confidence rating alongside it.

Boards required by area to board

Page defaults, not your figures above.

Area to boardBoards required (boards)
100 sq ft12
150 sq ft17
200 sq ft23
250 sq ft28
300 sq ft34

Frequently asked questions

Is backer board waterproof?
No, and this is the most consequential misunderstanding in bathroom tiling. Cement backer board is water-resistant — it will not turn to mush like plasterboard — but water passes through it. A shower needs a waterproofing membrane or a liquid-applied system over the board, or the water reaches the timber behind.
Can I use plasterboard instead?
Not in a wet area. Even moisture-resistant plasterboard degrades under sustained wetting and cannot carry the weight of tile once it does. Outside the wet zone, in a dry room, tiling onto plasterboard is normal practice.
Why alkali-resistant tape rather than ordinary mesh?
Because cement-based mortar is strongly alkaline and will degrade standard fibreglass tape over time. Alkali-resistant tape is made for this environment. The joint is also set in the tile mortar itself, not in a drywall compound, which has no place behind tile.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.