question on pizza slice size

If you look through the different options fo pizza it has the whole pizza cut into slices..usually 5 or 6...and then you can chose how many slices. That's how I figure out my calories.

I look for an entry in the database for that particular pizza - for the WHOLE pizza, then put in my portion as 0.5 of a serving if I ate half, or 0.25 if I had a quarter of it. 0.1 = one tenth of the whole thing, 0.8 = one twelfth (imagine a clock face when you work that one out). If you had a slice that would be like a clock showing 4 o'clock you had 4x0.8 = 0.32 more or less. It works.

The larger the pizza, the more calories per slice because the diameter is bigger.

With fast food entries, go with the size of pizza as they generally cut all pizzas of that size into the same number of slices (although some slices may be bigger than others, so having all the pieces on one half of a pizza should be exactly half of a whole pizza, and having slices directly opposite each other should average out the slice size).

With other pizzas, if you select (on the app, not sure about on the site) the serving size drop down, it should give you the option of the whole pizza (in which case you can use fractions or decimals depending on app/site) and if one serving is "1 slice" it should say how many slices make a whole pizza - if cut differently you can use fractions of slices or fractions of pizza.

You could also go by weight, but that's too much hassle for me.

Still depends how wide the whole pizza is and how many slices it's cut into. Plus deep dish or thin crust, what toppings. Look for one that's similar on the database and calculate from there.

If the pizza is from a local pizza place, ask them if they have the calorie information. They may be surprised you asked, but I bet they can provide it. (they may have to go to the manager, but oh well.)