Mixed Thai meal

When I go out to eat, I try to find the nutritional information for the restaurant online to input into my food log. If I can't find the nutritional information, I try to find the closest correct item in the database for it. Even if it makes me go over my daily limit for the day since being off by one day won't affect you all that much.
To play it safe so I'm not underestimating, if I'm sharing the food with friends, I prefer to split the dishes evenly between everyone. So, if it's two people sharing, I ate half (0.5) of each whole container serving. Even better if the portion sizes are under the metric system since the imperial system is totally inaccurate if you live in a country using the imperial system.
Of course, if you know you ate a dish less than the other, you can put a third (0.33333) of the container serving or a quarter (0.25) of the container serving. Etc., etc., etc. It's just one way to get you started. Personally, I think it's better to overestimate than underestimate what you ate.