Type into Google and it is easy - no calculations.
180 gms apple into google - straight away it comes back with 94 cals.
Have a laminated sheet with all my portions on it with weight and cal amount.
My usual portion of - say broccoli - I have 150gms. Sheet says 150gms Broccoli = 52 cals.
Always have a pad next to scales and write EVERYTHING down.
Start with daily calories allowed at top of page and deduct as I go along so I know how many left for the rest of the day.