Buy too little grout and you’re back at the shop mid-job with half a wall done. Buy too much and you’ve paid for bags that harden in the store cupboard. This grout calculator gets you close before you ever open a bag.
Areas to Tile
Tile & joint
Grout & packs
You need to buy
0 packs
Enter your area, tile size, joint width and depth, pick cement or epoxy, add a wastage allowance, and it tells you roughly how much grout you need — and how many packs to buy in kg or lb.
The thing most people get wrong is guessing grout from floor area alone. Area is only part of the story. Two rooms of exactly the same size can need very different amounts of grout depending on the tile and the joints. That’s the whole reason a proper calculator beats a rule of thumb.
How to Use the Grout Calculator
It’s quick:
- Enter the length and width of the area you’re tiling.
- Pick your unit — feet, metres, inches or centimetres.
- Choose your tile size from the list, or select Custom Size and type your own.
- Enter the joint width in millimetres.
- Enter the joint depth in millimetres.
- Choose your grout type: cement or epoxy.
- Set a wastage allowance.
- Pick the pack size you plan to buy.
- Hit Calculate Grout.
Got more than one room or several walls? Don’t do them one at a time. Use Add Another Area and let the calculator total everything up for you.
What You Need Before You Start
Five things drive the number. Have these ready:
| Information | Example |
|---|---|
| Tiled area | 200 sq ft |
| Tile size | 600 × 600 mm |
| Joint width | 3 mm |
| Joint depth | 8 mm |
| Grout type | Cement |
| Wastage | 10% |
If you already know how many tiles the job takes, our tile calculator and how many tiles in a box guide will help you cross-check your area first.
What Actually Changes How Much Grout You Use
Grout fills the gaps between tiles — so anything that changes the total length, width or depth of those gaps changes the amount you need. Three things matter most.
Tile Size
Picture two floors of identical area. One is laid in 300 × 300 mm tiles, the other in 600 × 600 mm. The smaller tiles create far more joints across the same space, so they eat noticeably more grout.
Rule of thumb: smaller tiles = more joints = more grout. Mosaics and subway tiles are the hungriest. Big-format 600 × 1200 mm and 800 × 1600 mm tiles are the leanest.
Joint Width
This is the biggest lever after area. A 2 mm joint holds a fraction of what a 5 mm joint holds. Widen the gap and grout use climbs fast.
But don’t shrink a joint just to save a bag or two. Go by the tile — rectified large-format tiles want tight joints; handmade or Athangudi-style tiles need wider ones to sit right. Follow the tile maker’s guidance, not your grout budget.
Joint Depth
Deeper joints hold more grout. A 3 mm joint at 8 mm deep uses more than the same width at 5 mm deep. That’s why the calculator asks for both width and depth — skip one and the estimate drifts.
Cement Grout vs Epoxy Grout
The calculator treats these two separately, and for good reason.
Cement grout is the everyday workhorse — powder mixed with water, used on most home floors and walls, kitchens and bathrooms. Affordable, easy to apply, easy to source.
Epoxy grout is a resin system. It resists stains, water and chemicals far better, which is why it shows up on backsplashes, wet areas and anywhere that gets scrubbed hard. It’s denser and behaves differently, so its coverage per kg isn’t the same as cement.
Because the density differs, always sanity-check an epoxy result against the coverage printed on that specific product. Epoxy formulations vary more than cement ones.
How Much Wastage Should You Add?
No calculation survives a real job untouched. You lose grout to mixing, spreading, filling, cleaning off the haze, and fussing around corners and edges.
The calculator gives you 0%, 5%, 10% and 15%.
- Simple, square room, measurements you trust? 5% is usually plenty.
- Multiple rooms, odd shapes, or you eyeballed the area? Go 10–15%.
For most jobs, 10% is a safe default. Better a little left over than a half-grouted floor and a trip back to the shop.
The Grout Formula (Simplified)
You don’t need to do the maths — the tool does — but here’s what’s under the hood.
Grout volume comes from the geometry of the tile and its joints:
Grout needed ≈ tile size × joint width × joint depth × area × grout density, then adjusted for wastage.
The calculator converts everything to consistent units, works out the joint volume across your whole area, applies the density for cement or epoxy, and adds your wastage. Because no two installs are identical, treat the answer as a solid estimate — not a guarantee.
A Worked Example
Say you’ve got:
- Area: 200 sq ft
- Tile: 600 × 600 mm
- Joint width: 3 mm
- Joint depth: 8 mm
- Grout: Cement
- Wastage: 10%
Type those in and the calculator returns a grout weight plus the number of packs for your chosen pack size.
Change the tile to 300 × 600 mm on that same 200 sq ft, and the number goes up — more joints. Widen the joint to 5 mm and it climbs again. Same floor, different job.
Tile Sizes You Can Calculate
The tool covers all the common sizes:
| Small & medium | Large-format |
|---|---|
| 200 × 300 mm | 600 × 600 mm |
| 250 × 375 mm | 600 × 1200 mm |
| 300 × 300 mm | 800 × 1200 mm |
| 300 × 450 mm | 800 × 1600 mm |
| 300 × 600 mm | 1000 × 1000 mm |
| 395 × 395 mm | 1200 × 1200 mm |
| 450 × 450 mm | 1200 × 2400 mm |
Tile not on the list? Choose Custom Size and enter the length and width in mm, cm or inches.
Floors, Walls, Bathrooms and Kitchens
Floors — living rooms, bedrooms, kitchens, balconies, hallways, commercial spaces. Measure length × width. If the room is L-shaped or irregular, split it into rectangles and add each as a separate area.
Walls — backsplashes, shower walls, feature walls. Measure length × height, and leave out big windows and doorways so you’re only counting tiled surface.
Bathrooms — rarely one number. You’ve usually got a floor, shower walls and other walls, often in different tile sizes. Add each surface separately:
- Floor: 6 ft × 8 ft
- Shower wall: 5 ft × 7 ft
- Other wall: 4 ft × 7 ft
Kitchens — floor and backsplash frequently use different tiles. If the floor is 600 × 600 mm and the backsplash is 300 × 600 mm, calculate them as two areas, because the tile size changes the grout draw.
kg or lb — Which Should You Pick?
Grout sells by weight, and the unit depends on your market.
- Kilograms — standard in India and much of the world. Common packs: 1, 2, 5, 10, 20 kg.
- Pounds — standard in the US. Common packs: 1, 5, 10, 25, 50 lb.
Toggle whichever suits where you’re buying and the calculator does the rest.
How Many Grout Packs Do I Need?
Once you’ve got the weight, the real question is bags to buy — and you can’t buy a fraction of a bag.
Say you need 7.4 kg and you’re buying 5 kg packs:
7.4 ÷ 5 = 1.48 → round up → 2 packs
The calculator always rounds up to the next whole pack, so you’re never left short.
Why Your Real Consumption Might Differ
A calculator gives you a planning number. On the floor, the actual figure shifts with:
- The tile’s true dimensions and edge profile
- Joint width and depth as actually laid
- An uneven or rough substrate
- The installer’s technique and how much gets wasted in cleaning
- The specific grout’s density and formulation
So use the estimate to plan and buy — then always compare it against the coverage figure on the bag. If you’re also sizing up adhesive for the same job, the tile adhesive calculator and how much tile adhesive do i need guide work the same way.
Buying Tips From the Trade
- Check the tile maker’s joint spec first. Some tiles are fussy about joint width — that decides your grout before anything else.
- Trust the grout bag’s coverage figure. Product formulations vary; the manufacturer’s number is the last word.
- Buy from one batch where you can. Cement grout colour can shift slightly between batches, and mismatched joints are hard to unsee.
- Keep a little back for repairs. Colours get discontinued. A leftover half-bag saves you later.
- Don’t shop on price alone. The right grout depends on the location, joint size, water exposure and how hard it’ll get cleaned — not just the cheapest bag on the shelf.
The Bottom Line
Grout isn’t a “buy two bags and hope” material. The four numbers that decide it are tiled area, tile size, joint width and joint depth — and grout type and wastage nudge the total.
Punch those into the grout calculator above, switch between kg and lb as needed, and it’ll tell you roughly how much to buy and how many packs. Then cross-check against your grout bag’s coverage before you head to the counter. Do that and you’ll finish the job on the grout you bought — no half-done floors, no wasted bags.
Frequently Asked Questions
How do I calculate how much grout I need? Enter your tiled area, tile size, joint width, joint depth and grout type into the grout calculator. It estimates the quantity and adjusts it for the wastage percentage you choose.
Does tile size affect how much grout I use? Yes. Smaller tiles create more joints over the same area, so they generally need more grout than larger tiles at the same joint width and depth.
How much grout do I need for 100 sq ft? There’s no single answer, because it depends on your tile size, joint width, joint depth and grout density. A 100 sq ft floor in 300 × 300 mm tiles needs far more grout than the same floor in 600 × 600 mm. Enter your details in the calculator for a real number.
How much grout do I need for 600 × 600 mm tiles? It depends on the total area plus your joint width, depth and grout type. Select 600 × 600 mm in the calculator and add the rest of your project details.
Can I calculate grout for 300 × 600 mm tiles? Yes. Pick 300 × 600 mm from the tile-size list and enter your area and joint measurements.
Can I use the calculator for wall tiles? Yes. It works for both floors and walls. For walls, measure length × height and leave out untiled sections like windows and doors.
Can I calculate epoxy grout? Yes — select Epoxy as the grout type. Because epoxy density and coverage vary by product, always compare the result with the manufacturer’s figure on the bag.
Should I add wastage to my grout estimate? It’s worth it. A little allowance covers what’s lost in mixing, application and cleaning. The calculator offers 0%, 5%, 10% and 15%; 10% is a safe default for most jobs.
Is the grout calculator 100% accurate? No calculator can promise the exact amount used on a real install — technique, substrate and formulation all play a part. Treat the result as a close estimate and check it against the grout maker’s coverage before buying.