It says it "estimates" the calories. If you look at the examples, it gives ranges that vary by 150 calories. That's quite a lot of wiggle room if you use it for 3 meals a day.
It's a gimmick. I would rather go by my own figuring, since I can tell if there is oil on the food, how much is actually there, etc.
I have tried it twice. Once it was off on calories by about 800. The other time it was spot on. I think I will only use it if I have no other way to help me estimate. Like at non-chain restaurants or when I go on a cruise. For chain restaurants I look it up on the LiveStrong App or Restaurants App.