MaterialEstimate › Interior Calculators › Mortar & Grout

Mortar & Grout Calculator

Enter your tile area, tile size, and joint width. Get mortar bag and grout bag estimates in seconds.

Mortar & Grout Calculator
✓ Your estimate
Mortar bags needed
--
50 lb bags of mortar
--
Grout Bags (10 lb)
--
Sq Ft Tiled
--
Sq Ft / Mortar Bag
--
Sq Ft / Grout Bag

What this estimate includes

This estimate covers 50 lb bags of thinset or medium-bed mortar and 10 lb bags of grout for your tile area. Coverage rates vary by tile size, joint width, and mortar type. Waste is added to account for cuts, spillage, and application variation.

How it's calculated

Mortar bags = (Area × waste factor) ÷ coverage per 50 lb bag Coverage per bag: thinset 30–42 sq ft, medium-bed 20–28 sq ft (varies by tile size) Grout bags = (Area × waste factor) ÷ coverage per 10 lb bag Grout coverage varies by tile size and joint width — larger tile with narrow joints needs less grout per sq ft

Worked example

Example: 80 sq ft kitchen backsplash, 4×4 tile, 1/8" joint, thinset

1
Area with 10% waste: 80 × 1.10 = 88 sq ft
2
Thinset: 88 ÷ 40 sq ft/bag = 2.2 → 3 bags of 50 lb thinset
3
Grout (4×4, 1/8" joint): 88 ÷ 17 sq ft/bag = 5.2 → 6 bags of 10 lb sanded grout

Before you buy

Buying tips

  • Buy from the same batch — grout color can vary slightly between production runs.
  • Large-format tile (18"+) requires back-buttering; plan for 20–30% more mortar.
  • Mosaic tile on mesh backing often needs full-coverage thinset — increase mortar estimate by 15%.
  • For wet areas (showers, steam rooms), use a waterproof membrane under the mortar bed.
  • Polymer-modified thinset provides better adhesion and flexibility for heated floors.
  • Check the mortar bag for the correct trowel notch size — notch size directly affects coverage.

Frequently Asked Questions

How many bags of thinset do I need for 100 square feet of tile?
For standard thinset and medium-sized tile (6"–12"), plan on about 1 bag of 50 lb thinset per 40–45 square feet. For 100 square feet you typically need 3 bags including a 10% waste buffer. Large-format tile (18"+) and mosaic tile may require more mortar per square foot.
What is the difference between thinset and medium-bed mortar?
Thinset mortar is applied in a thin layer (3/16" to 3/8") and works for most standard tile installations. Medium-bed mortar is a thicker product used for large-format tile (12" and bigger) where you need to float out subfloor imperfections. Medium-bed covers less area per bag because more mortar is applied.
Do I need sanded or unsanded grout?
Use unsanded grout for joints 1/16" to 1/8" wide. Use sanded grout for joints 1/8" and wider. For natural stone or polished tile, use unsanded grout even at wider joints to prevent scratching. Epoxy grout works for both widths and provides superior stain resistance.
How much waste should I add to my mortar and grout order?
Add 10% for simple square rooms and straight tile layouts. Add 15% for diagonal patterns, rooms with many cuts, or if this is your first tile project. It is better to have leftover material — dye lots and batch numbers can vary between purchases making matching difficult later.
Can I use the same mortar for floor and wall tile?
Most standard thinset works for both floors and walls, but check the bag for specific approvals. For wall tile, use a non-sag thinset rated for vertical surfaces. Heavy or large-format wall tile may need a polymer-modified thinset for better adhesion and resistance to slippage during installation.
How long does thinset mortar take to cure before grouting?
Standard thinset needs at least 24 hours before grouting, and 48–72 hours in high-humidity environments. Check the mortar bag for specific cure times. Rapid-set products may specify shorter wait periods. Walking on newly set floor tile should wait at least 24 hours even with rapid-set mortars.
Why does mortar coverage vary by tile size?
Smaller mosaic tiles often have mesh backing requiring full mortar coverage underneath, increasing mortar use per square foot. Large-format tiles require back-buttering in addition to troweling the floor, effectively increasing mortar use. The trowel notch size also affects coverage — larger notches use more mortar and reduce how many square feet one bag covers.
Disclaimer: This calculator provides planning estimates only. Actual mortar and grout quantities depend on tile size, substrate flatness, trowel notch size, and installer method. Always verify final quantities with your tile supplier before purchasing. See all interior renovation calculators.