Grout Calculator
Tile and joints
Typical porcelain: 3/8 in (0.375)
Pounds per bag
Grout needed
6.4 lbs
- Recommended type
- Sanded grout
- Joint width
- 1/8"
- With 10% extra
- 7 lbs
- 25 lb bags to buy
- 1 bag
- Coverage of one 25 lb bag
- 471 sq ft
- Grout volume per sq ft
- 0.83 cu in (at 110 lb/cu ft)
Mix full bags where possible so color stays consistent across the floor.
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Smart Tile Calculator keeps your tile jobs on your phone, offline. On iPhone? It's inside Roofing Calculator & Estimator.
Grout coverage chart
| Tile size | 1/16" joint | 1/8" joint | 3/16" joint | 1/4" joint |
|---|---|---|---|---|
| 2 x 2 in mosaic | 19 lb | 39 lb | 56 lb | 72 lb |
| 3 x 6 in subway | 10 lb | 21 lb | 30 lb | 39 lb |
| 4 x 4 in | 10 lb | 21 lb | 30 lb | 39 lb |
| 6 x 6 in | 6 lb | 14 lb | 21 lb | 27 lb |
| 12 x 12 in | 3 lb | 7 lb | 11 lb | 14 lb |
| 12 x 24 in | 2 lb | 5 lb | 8 lb | 11 lb |
| 18 x 18 in | 2 lb | 5 lb | 7 lb | 9 lb |
| 24 x 24 in | 2 lb | 4 lb | 5 lb | 7 lb |
Assumes 3/8" thick tile. Thicker tile increases these figures proportionally — a 1/2" tile uses about a third more. Add 10% for waste.
Sanded vs unsanded grout
The only real question is joint width, with one exception for scratch-prone tile. Sanded grout contains silica sand that stops the joint shrinking and cracking as it cures, so it is required for joints 1/8" and wider. Unsanded grout is smoother and clings to a vertical surface better, which makes it the choice for joints under 1/8" — and the mandatory choice for polished marble, glass and metal tile, where the sand in sanded grout will scratch the face permanently. If you are unsure with a delicate tile, test on a spare piece before grouting the wall.
Epoxy grout
Epoxy grout replaces the cement binder with resin and hardener. It is waterproof, stain proof and needs no sealer, which is why it is worth the extra cost on a kitchen backsplash, a shower floor, or any commercial job. The trade-offs are real: it costs roughly three to four times as much per square foot, it sets in about 45 minutes so you mix small batches, and haze has to be cleaned off before it cures or it stays. Buy epoxy by the kit and follow the kit's own coverage chart — the figures above are for cement grout.
Grout line width by tile type
| Tile type | Recommended joint | Grout type | Why |
|---|---|---|---|
| Rectified porcelain | 1/16" – 1/8" | Unsanded or sanded | Machine-cut edges are dead consistent |
| Pressed ceramic | 1/8" – 3/16" | Sanded | Size varies tile to tile; the joint absorbs it |
| Glass tile / mosaic | 1/16" – 1/8" | Unsanded or epoxy | Sand scratches the glass face |
| Polished marble / stone | 1/16" | Unsanded | Sand scratches a polished finish |
| Tumbled or cleft stone | 3/16" – 1/2" | Sanded | Irregular edges need a wide joint |
| Large format 15 in+ | 3/16" | Sanded | Bigger tiles vary more across the face |
| Subway 3x6 | 1/16" – 1/8" | Unsanded | Classic tight joint suits the look |
| Quarry / exterior paver | 3/8" – 1/2" | Sanded | Movement and freeze-thaw need the width |
Wider joints need sanded grout. Tile the manufacturer marks as rectified can go tighter than pressed tile of the same size.
Tools the pros use for this job
Grout Float
QEP 4 in. x 9.5 in. Molded Rubber Grout Float with Non-Stick Gum Rubber, Black
$10.97
Check price on AmazonA stiff rubber float packs joints fully instead of skimming them.
Grout Sponge
QEP 70005Q-6D 7.5 Inch x 5.5 Inch x 1.875 Inch Grouting, Cleaning and Washing Sponge, X-Large, 6-Pack
$8.97
Check price on AmazonRounded-edge sponges clean haze without pulling grout out of joints.
Grout Sealer
Cement grout stains fast — seal it once it cures.
As an Amazon Associate I earn from qualifying purchases.
Prices as of Oct 10, 2026, 6:33 AM UTC. Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Sealing the grout afterwards? See our grout sealer buying guide.
Choosing a float and sponge? See our grout tools buying guide — grout quantities from this calculator.
Do this math on the job site — in the free app
Smart Tile Calculator for Android: offline, in your pocket, free.
How this calculator works
The estimate uses the standard industry formula: grout volume scales with the perimeter of each tile, the joint width, and the tile thickness, divided across the tile face area.
Sanded vs unsanded: use sanded grout for joints 1/8" and wider, unsanded for 1/16" joints and for polished stone or glass that sand would scratch. Epoxy grout goes further per pound but is less forgiving to work.
Buy about 10% extra — mixing a partial second batch to match color mid-job is how you get visible shade lines.
Grout volume is driven far more by tile size than by area. A 100 sq ft floor of 2x2 mosaic at 1/8" joints uses roughly five times the grout of the same floor in 24x24 tile at 1/16" joints, because small tiles pack far more linear feet of joint into the same square footage. Pick your joint width with the spacer size guide before you order, size the mortar with the thinset calculator, and price the whole job with the tile cost calculator. First time grouting? Follow our step-by-step guide to grouting tile.
Frequently asked questions
How much grout do I need for 100 square feet of 12x24 tile?
With 1/8 inch joints and 3/8 inch thick tile, expect roughly 12–18 pounds — one 25 lb bag is usually enough, with margin.
Sanded or unsanded grout?
Sanded for joints 1/8 inch and wider. Unsanded for joints under 1/8 inch and for polished marble, glass, or any tile the sand could scratch.
Does epoxy grout use the same amount?
Roughly the same volume, but epoxy is sold by kit and covers more per pound. Follow the kit's coverage chart and mix only what you can install in about 45 minutes.
How wide should my grout lines be?
Rectified porcelain can go as tight as 1/16 inch. Standard pressed ceramic needs 1/8 inch to absorb size variation, natural stone 1/16 to 1/8 inch, and any tile over 15 inches needs at least 3/16 inch because larger tiles vary more in size.
How long before I can seal or use the grout?
Wait 24 to 72 hours before light use and a full 72 hours before sealing cement grout, so the moisture can leave the joint. Epoxy grout needs no sealer at all and is fully serviceable in about 24 hours.
Related calculators
- Tile Quantity CalculatorHow many tiles you need for any room, wall, or floor — with waste.
- Thinset & Mortar CalculatorBags of thinset by trowel notch size and coverage.
- Shower Tile CalculatorWalls, floor, curb, and niche for a full shower surround.
- Regrout Cost CalculatorRegrouting priced by joint length — pro vs DIY, cement or epoxy.
- Tile Cost EstimatorTotal project cost: tile, grout, mortar, trim, and labor.
Guides worth reading next
- Sanded vs Unsanded vs Epoxy Grout: Which One Do You Need?Grout types explained by joint width and location: when sand scratches tile, why epoxy wins in showers, and how much of each type a bag actually covers.
- How to Grout Tile: Timing, Technique and the Two-Sponge MethodGrout tile in four moves: mix small batches, pack joints diagonally, first wipe 10–20 min after packing, then buff haze. Plus when grout is cured.
- Grout Color: Match the Tile or Contrast It?What matching vs contrasting grout does to a room, why white grout is a maintenance commitment, and how to test color before committing to 200 square feet.