Have this ready
A visible meal, any preparation details you know, and a willingness to correct or replace the estimate.
Add what the photograph cannot tell you
A photograph shows the visible plate. It does not tell the app exactly how much oil was used, what is inside a sauce, or how heavy the food is. Add preparation and portion information you actually know. If you do not know, leave it uncertain rather than inventing an ingredient amount.
For a packaged food with a label, the label and actual serving can give you a more direct basis for the entry. For a dish you cooked from weighed ingredients, use the saved recipe if it still represents that batch. A camera need not be the entry method for every meal.
Check the food and serving separately
First inspect whether the app identified the right foods. Chicken with skin, breaded chicken and plain chicken are different entries. Then inspect the serving size. A correct food name does not prove that the app chose the amount you ate.
If the app shows ingredients, check for missing sides, drinks, dressing or toppings. Remove anything that was not on your plate. Do not add a second full-meal entry to compensate for an error in the first; edit or replace the original so both do not count.
Correct before confirming
123 Cal’s official listing describes adding notes before analysis and correcting the result by voice or text before confirmation. We make 123 Cal, and have not run a comparative accuracy test. Other photo-entry apps have their own review controls, which are worth trying with a familiar meal before paying.
A useful personal check is whether you can make a correction you understand: change the portion, add a missing ingredient, then inspect the updated entry. If the result remains implausible, use a manual record or a known recipe instead of repeatedly guessing until the number looks appealing.
Keep the uncertainty with the entry
For a restaurant dish with unknown ingredients, an edited photo result still contains uncertainty. It is not the same as nutrition calculated from measured ingredients. Avoid treating small differences between two app estimates as proof that one is accurate.
A photo-based food diary is not an allergen detector, a diagnostic tool or a source of medical dosing information. For those decisions, use verified ingredient information and advice from the relevant qualified professional.