Tile Grout Calculator
Estimate exactly how much grout you need for a tiling job — by weight, volume, and bags — based on your tile size, joint width, joint depth, and grout type.
Inputs
For walls and floors alike — just enter the rectangle being tiled.
Density varies — sanded is denser than unsanded; epoxy is the densest.
15% covers mixing loss, joint-depth variation, and re-grout touch-ups.
Tick "Include" to add bag size and price — the calculator will work out bags and cost.
Grout needed
About Tile Grout Calculator
The Tile Grout Calculator works out how much grout a tiling job actually needs — by weight, volume, and bags — so you don't over-buy or, worse, run out half-way through a Saturday. It uses the standard grout-coverage formula that factors in tile length, tile width, tile thickness (which sets joint depth), and grout joint width, then applies a density appropriate to unsanded, sanded, or epoxy grout.
It works for floor tile, wall tile, backsplash, shower walls, and outdoor patios in any standard rectangular area. Use it before you head to the store, before you hire a tiler for a quote, or after the tile is down and you're about to mix.
How to Use Tile Grout Calculator
- 1 Pick your unit. Imperial (feet for area, inches for tile, inches for grout, pounds for bags) or Metric (m / cm / mm / kg).
- 2 Enter the tiled area. Length × width of the rectangle you're tiling. For L-shapes, calculate each rectangle separately and add the results.
- 3 Enter tile size. Length, width, and thickness. Thickness sets joint depth and matters far more than you'd guess — a 3/8" tile uses ~3× the grout of a 1/8" mosaic at the same joint width.
- 4 Set the grout joint width. Type a value or tap a preset chip (1/16", 1/8", 3/16", 1/4", 3/8"). The grout type auto-switches to unsanded for < 1/8" joints and sanded for ≥ 1/8".
- 5 Pick a grout type. Unsanded, sanded, or epoxy. Density rises with type — epoxy weighs more per unit volume than sanded, which weighs more than unsanded.
- 6 (Optional) Add bag size and cost. Tick "Include," then enter bag weight (typical: 25 lb / 10 kg) and price per bag. The estimate panel shows bags to buy, coverage per bag, and total cost.
- 7 Order the "with waste" amount. The output already includes your waste percentage — buy the bag count shown, don't shave it back.
Frequently Asked Questions
What formula does this calculator use? ▾
Grout volume per tile = joint width × tile thickness × (tile length + tile width). That volume is divided by the tile's footprint with joints — (length + joint) × (width + joint) — to give grout volume per unit area, then multiplied by your room area. Weight is volume × grout density (1500–1750 kg/m³ depending on type), and bags = weight ÷ bag weight, rounded up.
Why does tile thickness matter so much? ▾
Tile thickness sets how deep the grout joint is. A 3/8"-thick floor tile creates a joint three times deeper than a 1/8"-thick mosaic, so it takes roughly three times the grout for the same joint width and area. Most calculators that ignore thickness undercount by 50% or more on thicker tile.
Sanded vs unsanded vs epoxy — which do I need? ▾
Unsanded grout is for joints under 1/8" and for polished or honed natural stone that sand would scratch. Sanded grout is for joints 1/8" and wider and for most floor and wall tile. Epoxy grout is the most stain- and water-resistant — typical for showers, pool surrounds, and commercial kitchens — but it costs 3–5× more and sets fast. The calculator auto-switches unsanded → sanded at the 1/8" threshold when you tap a preset.
What waste percentage should I use? ▾
15% is a good default — it covers mixing loss, joints filling deeper than the tile thickness in places, and a small reserve for repairs. Bump to 20–25% if you're using epoxy (it sets fast and any unused mixed batch is dead), or for irregular natural stone where joint widths vary. For huge jobs over 500 sq ft, 10% is usually fine.
How is "coverage per bag" calculated? ▾
Coverage per bag is your tiled area divided by the exact (un-rounded) number of bags the calculator needs. It's a useful sanity check against the coverage table printed on the grout sack — manufacturer tables typically assume a specific tile size and joint, so if their number is wildly different from ours, double-check that the assumptions on the bag match your job.
Should I round bags up or buy exact? ▾
Always round up — the calculator already does this. Running out of grout half-way through a wall is painful: the colour from a new bag, even the same product code, can shade slightly, and the seam will be visible. A spare half-bag stored airtight is cheap insurance.
Does this work for mosaic or hexagonal tile? ▾
For square or rectangular mosaic, yes — just use the individual chip's size, not the mesh sheet's size. For hexagonal tile, use the hex's flat-to-flat width for both length and width and add 5% extra waste; the result will be slightly under-counted because hexes have more joints per unit area, but it's in the right ballpark.
Is my data saved or sent anywhere? ▾
No. Everything runs in your browser. Your room size, tile dimensions, prices, and any other input never leave your device and nothing is stored on a server.