Small tiles create more joint length across the same floor area than large tiles. That is why a grout estimate needs tile dimensions, joint width and depth as well as the overall tiled area.
The Whatson Tile Grout Calculator estimates mass from those dimensions, then rounds it to the product pack size you enter.
Put all the joint geometry in millimetres
Tile length and width, joint width and joint depth are millimetres. Density is kg per litre. The treatment area can be square feet or square metres.
Joint depth should describe the space being filled. The tool does not inspect adhesive left in a joint or determine how much product will be lost during application.
The calculation uses:
kg/m² = (tile length + tile width) × joint width × joint depth × density ÷ (tile length × tile width)
This geometric consumption relationship is also published in Sika’s SikaCeram 530 product information. Using the formula does not mean every grout has that product’s density or application limits.
One pack for the example floor
For a 300 sq ft area, enter 600 × 600 mm tiles, 3 mm joints, 8 mm joint depth, density 1.78 kg/litre, a 5 kg pack and 5% allowance.
The checked theoretical consumption is 0.1424 kg/m². With the area and allowance applied, the total requirement is 4.17 kg. The purchase rounds to one 5 kg pack.
A different tile size or wider joint changes the mass even when the floor remains 300 sq ft. This is a better basis for comparing quantities than assuming a pack always covers a fixed room size.
Product selection still comes first
Use the density and joint limits for the intended grout. A calculator accepting an 8 mm joint width does not tell you a product rated only for narrower joints will work there.
Irregular tile edges, variable depth and application loss may need a different allowance. Movement joints and their sealant are separate from this cement or resin grout estimate.
Keep tile purchasing separate
The Tile Calculator estimates tiles and boxes. It cannot supply the joint dimensions for you, and buying extra tiles does not automatically mean you should grout the spare tile area.
The grout rate is PKR per pack and prices the rounded purchase. Adhesive, sealant, labour and cleaning materials are outside that figure. Save the input dimensions with the result so the estimate can be checked if the tile or grout changes.