Free Online Calculators
Tiles, adhesive & grout quantity calculator
This tile calculator tells you exactly how many tiles you need for your project, including a waste allowance, plus how much adhesive and grout to buy. Just enter the room area and tile size and the calculator does the rest. No more guessing at the DIY store.
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Whether you're tiling a bathroom floor, a kitchen backsplash, or an entire living room, knowing exactly how many tiles you need before you buy saves time, money, and frustration. The basic formula is simple: divide the total area of the room by the area of one tile. But real projects are rarely that clean. Doorways, odd corners, and cutting waste all add up fast, which is why a dedicated tile calculator makes a real difference.
A good rule of thumb is to add at least 10% waste for straight lay patterns, 15% for offset (brick bond) patterns, and up to 20% for diagonal patterns. Diagonal layouts generate more offcuts because tiles need to be cut at 45-degree angles along every wall edge. For example, if your room measures 4m × 5m (20 m²) and you're using a diagonal pattern, you'd want to purchase enough tiles to cover roughly 24 m² to account for cutting loss and breakage.
Most DIYers focus only on tile count and forget about adhesive and grout until they're standing in the hardware store. Tile adhesive coverage typically runs between 4–6 kg per square metre depending on the tile size and substrate. Larger format tiles (600×600mm or bigger) often need a thicker bed of adhesive, so consumption edges toward the higher end. For our 20 m² example at 5 kg/m², you'd need approximately 100 kg of adhesive — that's about five 20 kg bags. The calculator uses a flat 4 kg/m² on the area including waste, which gives 88 kg for 20 m² with 10% waste; use the rate on your bag if it differs.
Grout quantity depends on tile size, grout joint width, and tile thickness. Small tiles need more grout per square metre than large ones, because every square metre holds more metres of joint, and wide joints need more than narrow ones. The calculator uses the standard manufacturer formula: grout (kg/m²) = (tile length + tile width) ÷ (tile length × tile width) × joint width × joint depth × 1.6, all in mm, with the joint depth equal to the tile thickness. A 300×300 mm tile with a 3 mm joint and 8 mm thickness needs 0.26 kg/m², so a 20 m² floor takes about 5.1 kg, or 5.6 kg on the area including 10% waste, which is what the calculator shows. Getting this number right means fewer emergency trips back to the store mid-project, especially if you're using a colour-matched grout that may not be easy to find in a hurry.
At simple-calculator.online, the tile calculator handles all of these variables automatically — just enter the floor area in m², tile size, joint width, tile thickness, waste percentage and laying pattern, and it instantly shows you tile count, adhesive weight, and grout quantity in one place. For a diagonal layout it adds 5 percentage points to your waste figure, for a one-third offset 3 points.
Straight lay is the most material-efficient pattern and the easiest to install — tiles align in a simple grid. Offset (or brick bond) shifts each row by half a tile, creating a classic staggered look popular in kitchens and hallways. Diagonal patterns rotate the grid 45 degrees, adding visual interest but also adding complexity and waste. For awkward rooms with multiple recesses or obstacles, straight lay is the safest choice to minimise offcuts and keep costs predictable. The calculator offers straight, diagonal and a one-third offset.
Add 10% for straight patterns, 15% for offset, and 20% for diagonal. If your tiles are from a single batch, buying a few extra is always smart since dye lots can vary between production runs.
Multiply your floor area in m² by the adhesive coverage rate shown on the product bag (typically 4–6 kg/m²). Always check the manufacturer's spec sheet for the exact product you're using.
Yes. Simply measure the wall area (width × height) and subtract any openings like windows or doors. The same waste percentages and material calculations apply for wall installations.