You can fill it with about 3 litres of liquid. But you don't need the appliance for liquid food. Up to 600 g of vegetables, 1 kg of chips, 2 large pork fillets etc. can be processed without any problems.
I measured a tub, it's 15x21.5 cm and about 10cm deep (with the grid at the bottom or 12.5 without). That's about 3 litres of capacity (with the grid).