If you go to Tesco's website and look up a food, it will show the specific energy content.
You have to be a bit careful with dried stuff, so look for the 'as consumed'.
I know I have said this before, but going to state it again, we should really be using kJ for energy, not kCal.
kJ is a derived unit from the SI system, the the J, for joule, being a unit of energy.
It is made up of the base units of kilogram, metre and second.
kg x m^2 x s^-2