Hi I normally best guess my grout needs for a job, have this job the tiles are 25mm thick on average, average 320mm long x 220mm. 35 sq meter. They want a 10mm joint as they tge tiles are bowed and and miss shapen. Used an app to work out the grout needs and it comes up with 105kg. Anyone got a sum i can use or know if this is right. Cheer.