.png "Gram to Calorie Calculator 1"){kind=logo}
Gram to Calorie Calculator
Scale a food's calories, and optionally its protein, carbs and fat, from a known amount to your own real portion size
Type at least 2 characters to search from our UK foods database
Your favourites ♥
Trending Now 🔥
Request to be added
FSA Traffic Lights
Based on FSA traffic-light thresholds per 100g
| Nutrient | Per | Per 100g | % RI* |
|---|
*Reference Intake of an average adult (8400kJ / 2000kcal)
Buy online:
Your meal is empty
Go to "Food Lookup", select a food and click "+ Add to Meal" to start building.
Saved Templates
| Nutrient | A | B |
|---|
Mifflin-St Jeor formula · TDEE
Remaining today: 0 kcal
No real foods in our database fit that budget yet.
Scale a known amount to your own real portion
Enter the amount and calories shown on a label, a recipe, or another calculator, then your own real portion size. Works for any food, any unit, as long as the amount and the portion use the same unit.
What Is Gram to Calorie Scaling?
Almost every source of calorie information, whether it is a packet’s nutrition label, a recipe, a restaurant menu, or this site’s own food database, gives you figures for one specific reference amount. That reference amount is often 100g, but it can just as easily be a whole pack, a single item such as one egg, or whatever serving size the manufacturer happened to choose. The amount you are actually about to eat is very often a different number.
This calculator does the proportional maths for you. Enter a known amount and its real calories (and, if you have them, its protein, carbs and fat), then enter your own real portion, and it scales every figure to match, so you always know what you are actually eating, not just what the label says for a different amount.
How This Calculator Works
The maths behind this tool is simple proportional scaling, the same principle every “per 100g” nutrition label conversion already relies on. Your real portion’s calories are found by multiplying the known calories by the ratio of your amount to the known amount:
- Your calories = known calories × (your amount ÷ known amount)
The identical ratio is applied independently to protein, carbs and fat whenever you enter them, so a food with an unusually high protein content per gram still scales correctly even if its calorie density is average.
For example, if a label states 250 kcal per 100g and you are actually eating 160g, your real total is 250 × (160 ÷ 100) = 400 kcal. The calculator does this division and multiplication instantly, for calories and for every macro you provide.
When You’d Use This
This is a genuinely common, everyday problem, not a niche one. A few real situations where gram-to-calorie scaling matters:
- A packet lists calories “per 100g”, but you weighed out 145g on a kitchen scale.
- A recipe or restaurant menu states calories for one whole dish or serving, and you are eating half of it, or a larger helping.
- You want to check the calories in a homemade dish scaled up or down from its original recipe amount.
- You already know a food’s calories per serving from another source (a label, a website, this site’s own food database) but need the figure for a genuinely different portion size.
Once you know your real, scaled totals, you can look up any of the 5,200+ UK foods in our Food Calorie Calculator to log exactly what you eat, or check how it fits your daily target with the TDEE Calculator.
Frequently Asked Questions
Does this work for any food?
Yes. This tool scales the calories and macros you already know for a food, it does not look them up itself. As long as you have a real known amount and its real calories (from a nutrition label, a recipe, or any other source), the scaling works for any food.
Can I scale protein, carbs and fat too, not just calories?
Yes. Enter any of protein, carbs or fat you know for the known amount, and each one scales using the exact same ratio as calories. All three are optional, so you can scale calories on their own if that is all the information you have.
What if I only know calories per serving, not per gram?
That’s fine. The known amount does not have to be in grams. It can be any consistent unit, a serving, a slice, 100g, or a whole pack, as long as you enter your own real portion measured the same way.
Is this the same as just multiplying by a percentage?
Conceptually, yes. Scaling to 150% of a known amount gives the same result as multiplying by 1.5. This calculator works out that ratio and applies it automatically, so you don’t have to do the division by hand.
Why doesn’t this calculator search a food database like the main calculator?
By design. This tool is built specifically for scaling a known figure you already have, from any source, to a different amount. If you would rather search our own 5,200+ UK foods directly, use the Food Calorie Calculator instead, which shows calories and macros without needing a known figure to scale from.