You do the other way around, you see the total weight of the thing, you guesstimate how much you are gonna eat and you do the math. Half of 500g is 250, so x2.5 whatever is on the 100g nutritional panel.
It’s not about when you would use the per 100g it’s about 100g being easy to be transformed into other units so you get an easy multiplier you can apply to the values.
I always used the 100g as percentage since the rest of the nutrients is also listed as g. So if there is 9g of protein per 100g, then i can just make an easy approximation for whatever the serving is.
You do the other way around, you see the total weight of the thing, you guesstimate how much you are gonna eat and you do the math. Half of 500g is 250, so x2.5 whatever is on the 100g nutritional panel.
It’s not about when you would use the per 100g it’s about 100g being easy to be transformed into other units so you get an easy multiplier you can apply to the values.
I always used the 100g as percentage since the rest of the nutrients is also listed as g. So if there is 9g of protein per 100g, then i can just make an easy approximation for whatever the serving is.