Floors & Walls
Thinset Calculator
Estimate thinset mortar bags from area and the product's coverage for your trowel.
Enter your measurements
Results update as you type.
About this calculator
Enter the area to tile and the manufacturer's coverage per bag for your trowel notch and substrate — both affect coverage. Add an allowance and an optional bag price. No universal square-feet-per-bag value is assumed.
How to use this calculator
- Measure the area to be tiled.
- Read the bag's coverage for your trowel notch and substrate.
- Enter it with an allowance.
- Calculate for whole bags and purchased coverage.
Formula
Order area = area × (1 + allowance ÷ 100)
Bags = ⌈order area ÷ coverage per bag⌉
Purchased coverage = bags × coverage per bag
Assumptions
- Coverage depends on trowel notch, substrate flatness and product — the editable coverage shown in the form is used.
- The allowance is applied once before rounding up to bags.
- The trowel/substrate context you use is displayed with the result.
Common mistakes
- Using a coverage or yield for a different product, depth or application.
- Adding waste twice in both the measured quantity and allowance field.
- Treating a bag count as proof that the selected product is suitable for the installation.
Worked example
Try it: press “Load example” above the form.
Illustrative supplied coverage: 300 ft² with 10% extra is 330 ft². At a product-and-trowel coverage of 60 ft² per bag, buy 6 bags (360 ft² of coverage). Enter the actual yield for your chosen product and method; this example is separate from the named 1/4 in notch reference.
Limitations
No automatic trowel choice, no tile-bonding suitability assessment and no universal square-feet-per-bag preset.
Frequently asked questions
Which trowel does the default refer to?
The named reference is plain VersaBond Professional Thin-Set in a 50 lb bag with a 1/4 × 1/4 × 1/4 in square-notch trowel. Its cited chart gives 85–95 ft². The editable 90 ft² value lies within that range; it is not a universal yield or the conservative lower end. VersaBond LFT has a different chart.
Will back buttering change the quantity?
It can. Substrate flatness, trowel angle, tile backs and required contact affect consumption. Change coverage to match the actual product chart and installation method.
What does the worked example show?
Illustrative supplied coverage: 300 ft² with 10% extra is 330 ft². At a product-and-trowel coverage of 60 ft² per bag, buy 6 bags (360 ft² of coverage). Enter the actual yield for your chosen product and method; this example is separate from the named 1/4 in notch reference.
Which assumptions should I check before using the result?
No automatic trowel choice, no tile-bonding suitability assessment and no universal square-feet-per-bag preset.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
- CUSTOM: VersaBond coverage chart
Plain VersaBond Professional Thin-Set, 50 lb, 1/4 in square notch: 85–95 ft². The separate VersaBond LFT chart lists 90–100 ft². Actual product, trowel and conditions govern; the 90 ft² form value is illustrative.
Calculation documentation · Updated 2026-11-11 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
Related calculators
All Floors & Walls calculatorsTile Calculator
Estimate tiles and boxes for a room from area, tile size and waste allowance.
Open →Grout Calculator
Estimate grout bags from tiled area using the manufacturer coverage or your measured consumption.
Open →Self-Leveling Concrete Calculator
Estimate self-leveling compound bags from area, average depth and product yield.
Open →Flooring Calculator
Estimate flooring cartons from room area, waste and the manufacturer's coverage per carton.
Open →Wallpaper Calculator
Estimate wallpaper strips and rolls using real roll geometry — not just wall area.
Open →Siding Calculator
Estimate siding cartons from wall area, openings, waste and effective coverage.
Open →