Construction Material Estimate

Can’t change any of the values so it calculates blocks at 200mm x200xx400 when UK blocks are 225 x 100x 450 mm so utterly useless , it’s all in cm when the trade works in mm , it is quicker to do concrete calculations in head than use this , I have used other apps and you input what size bags of cement you use and it will tell you how many bags you will need , totally useless and a waste of money