The Serving Amount Calculator works backward from a calorie, kilojoule, or macro target to the serving amount that hits it. Instead of nudging a serving up and down to see what fits, you enter the number you are aiming for and let Carbon size the portion for you.
What is the Serving Amount Calculator?
The Serving Amount Calculator is a tool inside the add-food flow that turns a nutrition target into a serving size. Pick calories, kilojoules, protein, carbs, or fat, type the amount you want, and Carbon calculates the serving of that food or recipe that delivers it. Most trackers only run in one direction: you set a serving and read the macros. Carbon lets you run it the other way, which is faster when you are building a meal around a specific protein goal or a set calorie budget.
Hitting a precise protein or calorie number by hand usually means trial and error. The calculator removes that step, so logging planned meals stays quick and your diary reflects what you actually intended to eat. Consistent, accurate logging is what feeds Carbon's weekly check-in and target adjustments.
Where to find the Serving Amount Calculator
The calculator lives on a food or recipe profile inside the add-food flow. Open a food or recipe, tap the serving amount to open the number keyboard, then tap the SERVING AMOUNT CALCULATOR row to expand it.
How to calculate a serving amount
Open a food or recipe profile from the add-food flow.
Tap the serving amount so the number keyboard opens.
Tap the SERVING AMOUNT CALCULATOR row to expand it.
Choose Cal or kJ, Protein, Carbs, or Fat.
Enter the nutrition amount you are aiming for.
Review the serving Carbon calculates, then add the food or recipe when you are ready.
The serving field updates as you type. The selected nutrition field and the serving field share the same color, so it is always clear which value is driving the calculation.
Example: sizing a food to 25 g of protein
Say you want 25 g of protein from a food:
Expand SERVING AMOUNT CALCULATOR.
Tap Protein.
Enter 25.
Carbon updates the serving to the portion that provides 25 g of protein, or the closest available result for that food.
You can run the calculation again with calories or a different macro before you add the food.
How the calculation handles rounding
The calculator uses the same nutrition values shown on the food profile and follows your calorie/kilojoule and Label Calories/Macro Calories preferences. It aims for a clean serving amount, either a whole number or up to two decimal places. Food data and display rounding sometimes make an exact match impossible, and in that case Carbon selects the closest serving to the value shown. Always review the final serving and nutrition numbers before adding the food.
Frequently asked questions
Why is one of the calculator choices dimmed?
Carbon cannot size a serving from a nutrient the food does not contain. Fat is dimmed when the selected food has zero fat per serving, for example. Choose calories or a macro with a value greater than zero.
Why am I not seeing the calculator?
The Serving Amount Calculator may not appear when the serving field and number keyboard are not open, or you are viewing an alcohol or import profile. The calculator is currently available on food and recipe profiles.
Can I target calories and a macro on the same food?
Yes, one at a time. Enter a target for one field, review the serving, then switch to another field and enter a new target before adding the food.
Does the calculator change the food's nutrition data?
No. It only sets the serving amount for the entry you are adding. The food's underlying nutrition values are unchanged.
Additional details
The calculator is a sizing tool, not a substitute for review. Confirm the serving and macros match the portion you actually ate before adding.
Results follow your existing calorie/kilojoule and Label/Macro Calories preferences.
Available on food and recipe profiles in the add-food flow. Alcohol and import profiles are not currently supported.
For the standard way to add and edit foods, see How to add food and Macro tracking basics.