help how do i work it out?

hiya everyone excuse me if i'm writting in wrong place!! but how do you work out some cals and fat content of hm food? i keep using some one else input which is on the data base, but find it hard to believe that there is that many cals/fat in the chilli i make lol i use lean mince, i halve it which is 250g and have enough for like a wk of chillies!! i use tinned toms, mushrooms, onion, garlic, peppers, chillies, powders, celery 2 oxo cubes salt, pepper. so what do you think per meal/portion, each time iv'e eaten it, its usually about 150g per portion or 200g but obv the 250g i used to start is not in the one meal lol so how do i work it out!!

please help x