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Grout calculator

Tile piece count is done. Now the aisle question is bags of grout. Joint width and tile thickness change the volume more than people expect — a 1/8 in joint on 12×12 is a different shopping list than pencil joints on mosaics. Enter floor or wall area (or tile size × count), joint width, tile thickness, and waste. Read approximate volume and bags from the coverage on the bag you actually buy. This page does not choose sanded vs unsanded for you.

ft
ft
sq ft
Optional
in
in
in
in
≈ tile thickness
sq ft
Optional — from carton chart
cu ft
If no coverage
12%
0510152025

+12% so you don't come up short

ORDER ESTIMATEGROUT
Bags to buy1
Area80 sq ft
Order volume0.04 cu ft
Waste12%
How it calculates
tiles from unit (tile+joint); joint cu ft ≈ tiles × ((W+j)(H+j)−W×H)×depth ÷ 1728; bags = ceil(order cu ft ÷ bag yield).

Estimate only — not a contractor bid. Confirm bag yields and local codes before you pour or order.

When to use

Bathroom or kitchen tile shopping list after you know the tile; checking a contractor’s bag count against your joint width; leftover tile jobs where the old grout brand is gone.

When not to

Epoxy grout with weird kit yields — use the kit label. Large-format thin-set coverage is a different product. Structural masonry grout for CMU cells → that is wall fill, not tile joints (see block work separately).

Assumptions

Approximate joint volume ≈ area × (joint_fraction) using tile face + joint width geometry, or simplified “coverage sq ft per lb/bag” from the carton. Waste default 10–15% (narrow joints and cleanup eat more). Bag coverage on the package wins over any website table. Sanded vs unsanded is a product choice, not a different area formula.

Worked examples

Example 1

80 sq ft floor, 12×12 tile, 1/8 in joints, waste 15%, bag covers ~50–70 sq ft at that joint (enter carton)
→ roughly 2 bags after waste for a typical sanded bag — confirm carton

Wider joints or thicker tile jump a bag fast.

Example 2

40 sq ft shower walls, mosaic sheet, 1/16 in joints, waste 20%
→ often 1 bag still covers if the carton lists high sq ft

Mosaics waste more on cleanup than on math. Buy the color you can match later.

How it calculates

Net tiled area, then joint volume or carton coverage, then waste and bags.

  1. Enter area (or L×W), tile size, joint width, and grout depth.
  2. Or enter bag coverage sq ft from the carton chart.
  3. Dial waste; read bags on the ticket.
net tiled area (sq ft)
joint volume from tile L×W, joint width, and thickness — or bags = ceil(area × (1+waste%) ÷ bag_coverage_sq_ft)
order = volume × (1 + waste%); bags = ceil(order ÷ bag_yield)

Common traps

  1. Carton coverage beats theory — humidity, joint depth, and how hard you pack change yield.
  2. Sanded vs unsanded — wrong type is a failure mode, not a calculator bug.
  3. Haze and cleanup burn product; skinny waste % on mosaics is optimism.
  4. Mixed tile sizes on one floor — calculate the largest joint case or split zones.

Next tool

Tile piece count first → tile calculator.

After cure, paint trim → paint calculator.

FAQ

Use tiled area, joint width, and the bag’s coverage chart; add waste; round up bags.

Related

Estimate only — not a contractor bid or engineered takeoff. Confirm bag yields and local codes before you pour or order.