To work out how many bags of thinset you need, divide the tiled area by the coverage per bag that the mortar’s data sheet gives for your trowel notch, then round up. The notch matters as much as the area: one widely used mortar covers 80 to 95 square feet per 50 lb bag with a 1/4 inch square notch, but only 35 to 40 with a 1/2 inch notch. MeasureSet, a Windows app from Automata Labs, measures the tiled areas on a PDF floor plan and turns them into an order quantity once you tell it what one bag covers.
This guide shows where the coverage numbers come from, works through a full example, and explains how to do the takeoff from the plans.
Measure tile areas on the plan PDF and get bag counts in Excel.
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Why does the trowel notch change the bag count so much?
A notched trowel leaves ridges of mortar. A bigger notch leaves taller, wider ridges, so the same bag covers less floor. Larger tile usually needs a larger notch to get full contact on the back of the tile, which is why big-format jobs eat mortar.
Every manufacturer publishes coverage per bag by notch size on its product data sheet. As an example, the data sheet for LATICRETE 254 Platinum, which we read today, lists:
| Trowel notch | Approximate coverage per 50 lb bag |
|---|---|
| 1/4 x 3/16 in (6 x 5 mm) | 105 to 115 sq ft |
| 1/4 x 1/4 in (6 x 6 mm) | 80 to 95 sq ft |
| 1/4 x 3/8 in (6 x 9 mm) | 60 to 70 sq ft |
| 1/2 x 1/2 in (12 x 12 mm) | 35 to 40 sq ft |
The same sheet warns that “coverage will vary depending on trowel notch size, type and size of tile and substrate.” Other mortars publish different numbers, so always use the data sheet for the product you are buying.
How do you calculate the number of bags?
The formula is short:
Bags = tiled area ÷ coverage per bag for your notch, rounded up.
Three choices make the answer safer:
- Use the low end of the coverage range. If the sheet says 60 to 70, divide by 60. The range already reflects real-world variation.
- Measure only the tiled area. Skip cabinets, tubs and built-ins the tile will not go under, but include any area where the tile does run underneath.
- Add back-buttering if your tile needs it. The LATICRETE sheet says to “back butter large tiles >8” x 8” (>200 mm x 200 mm) to provide full bedding and firm support.” That uses extra mortar beyond the trowel coverage, so many installers round up by an extra bag on large-format work.
What does a worked example look like?
A ground floor has tile in the kitchen, entry, powder room and laundry. From the plan:
| Room | Tiled area |
|---|---|
| Kitchen (less island footprint) | 196 sq ft |
| Entry | 88 sq ft |
| Powder room | 36 sq ft |
| Laundry | 64 sq ft |
| Total | 384 sq ft |
Bags for each notch, using the low end of the LATICRETE 254 Platinum range:
| Tile and notch | Coverage used | 384 ÷ coverage | Bags to order |
|---|---|---|---|
| 12 x 12 in tile, 1/4 x 1/4 in notch | 80 sq ft | 4.8 | 5 |
| 12 x 24 in tile, 1/4 x 3/8 in notch | 60 sq ft | 6.4 | 7 |
| 24 x 48 in tile, 1/2 x 1/2 in notch | 35 sq ft | 11.0 | 11, plus extra for back-buttering |
The same floor needs anywhere from 5 to 11 or more bags depending on the tile. That is why a mortar quantity copied from a previous job is often wrong.
Turn room areas into cartons of tile and bags of mortar in one takeoff.
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How do you measure the tiled area from a PDF plan?
If you have the plans as a PDF, you can measure on the PC instead of scaling with a ruler. In MeasureSet:
- Open the plan PDF and set the scale. MeasureSet reads the printed scale and offers it. Check it against a long printed dimension; our guide on setting the scale on a PDF drawing explains why.
- Create a label for the tile. Type a label such as “Floor tile” and click inside each room that gets it. A closed room’s floor area is one click inside it, wall to wall, even where walls are drawn as two lines.
- Outline open areas by hand. Open-plan spaces and rooms without a closed outline need an outline drawn point by point.
- Deduct what is not tiled. Outline an island or built-in footprint and tick Deduct from the total.
- Tell the label what one unit covers. Give the label a unit, such as bag, and the coverage per bag for your notch, such as 60 sq ft. The totals then show what to order.
- Add a second label for the tile itself. Use cartons and the carton coverage from the tile box. Our guide on how many boxes of flooring to order covers carton maths and waste.
- Export. MeasureSet exports Excel with blank price columns, a .csv, and a marked-up PDF with the totals.
For walls, such as a shower surround or backsplash, give a length label a height and MeasureSet calculates the wall area from length times height, minus openings with their own heights.
Does a waste allowance apply to mortar?
Tile gets a waste allowance for cuts and breakage. Mortar is different: the coverage range on the data sheet is the main allowance, and back-buttering is the main extra. If you add a waste percent to the mortar label, keep it small and say so in your estimate, so the next person knows why the number is higher than the area suggests. MeasureSet lets you set a waste percent per label, and every mark with that label carries it.
What about grout?
Grout quantity depends on tile size, joint width and joint depth, so it is calculated differently: per carton of tile or per tiled area from the grout maker’s chart. Treat it as its own label with its own coverage figure from that chart.
Frequently asked questions
How many square feet does a 50 lb bag of thinset cover?
It depends on the product and notch. The LATICRETE 254 Platinum data sheet lists 80 to 95 sq ft with a 1/4 x 1/4 inch notch and 35 to 40 sq ft with a 1/2 x 1/2 inch notch. Check the sheet for your product.
Should I round up?
Yes. You cannot buy part of a bag, and running short mid-floor is worse than one leftover bag.
Does MeasureSet know thinset coverage?
No. You enter the coverage from the data sheet for the mortar and notch you are using. MeasureSet does the measuring and the division.
Can I take off tile from a scanned plan?
If the scan is to scale and the scale is printed or a long dimension is shown, you can calibrate from it. Check a second dimension before you trust the totals.
Try MeasureSet
MeasureSet is a one-time purchase in the Microsoft Store with a free trial. There is no account and no upload, and your plan PDFs are never written over. See the MeasureSet product page for more, and our guide to calculating flooring square footage from plans for the area side of the job.
Measure once, then order tile, mortar and grout from the same takeoff.
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LATICRETE and 254 Platinum are trademarks of LATICRETE International, Inc. Automata Labs is not affiliated with LATICRETE.
Last updated 22 October 2026. Published by Automata Labs, a software company in Canada.