You can use this conversion tool to estimate the number of meals distributed based on lbs of food distributed.
Food distribution programs usualy work with a logic model that includes the Reach indicator "meals distributed." If you don't track that metric directly, you can use the following converstion tool to estimate that figure.
According to the USDA, 1.2lbs = 1 meal so this is relevant in the U.S. and is the metric used by Feeding America.
The calculation of 626 grams = 1 meal is based on a global standard from UN-FAO data (FAOSTAT) - an authoritative independent source.
According to “What the World Eats.” The average amount of food consumed around the world is 1878 grams/day, or an average of 626 grams per meal. While it is not a dietary guideline nor a prescriptive measure of what should be eaten--in other words, how much food one needs to have a varied diet and be properly fueled to lead a healthy, active life--it does break down the overall gram total into food groups as well as by country for several countries across the globe.
That said, there is no global standard for measuring meals by weight. There are multiple measures for meal size, typically by calorie (kcals) or nutrient, and regional/national variability for cultural preferences and practices, and socio-economic factors which add to national and regional variability (such as larger meal portion sizes in High-Income Countries), but there is no one global standard for how many grams an average person should eat per meal. Therefore, relying on UN-FAO data is the best option in the face of considerable variability.