CALCULATOR
Fat Intake Calculator
Daily fat in grams, with the minimum your body needs for hormone production and vitamin absorption.
Your fat target
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Estimate based on the Mifflin-St Jeor equation. Adjust over 2-3 weeks based on real-world results. General guidance, not medical advice.
Setting fat intake, and the floor you should not go below
Dietary fat is essential in a way carbohydrate is not. It supplies fatty acids the body cannot make, it is required to absorb vitamins A, D, E and K, and it plays a direct role in hormone production. This is why the calculator applies a floor of roughly 0.6 grams per kilogram of bodyweight regardless of your chosen split.
At 9 calories per gram, fat is also the most energy-dense macronutrient, more than double protein or carbohydrate. That makes it easy to overshoot calories with small amounts, and equally makes it an efficient way to add calories when trying to gain weight.
Above the health floor, how much fat you eat is largely preference. Some people feel better with higher fat and fewer carbohydrates; others prefer the reverse. Both work when protein and total calories are matched, so choose the split you can actually sustain.
How fat intake is calculated
minimum = bodyweight (kg) x 0.6
The calculator uses whichever is higher.
Fat targets by style, 80 kg at 2,650 kcal
| Style | Percent of calories | Fat grams | Above the floor? |
|---|---|---|---|
| Higher carb | 22% | 65 g | Yes, floor is 48 g |
| Balanced | 28% | 82 g | Yes |
| Lower carb | 35% | 103 g | Yes |
Types of fat and where they come from
| Type | Main sources | Guidance |
|---|---|---|
| Monounsaturated | Olive oil, avocado, almonds | Emphasise |
| Polyunsaturated omega-3 | Oily fish, walnuts, flax | Emphasise, often under-eaten |
| Polyunsaturated omega-6 | Seed oils, nuts | Adequate in most diets |
| Saturated | Butter, fatty meat, coconut | Include, moderate |
| Trans fat | Industrially processed foods | Avoid |
Fat content of common foods
| Food | Serving | Fat | Calories |
|---|---|---|---|
| Olive oil | 1 tbsp | 14 g | 119 kcal |
| Almonds | 30 g | 15 g | 173 kcal |
| Avocado | half, 100 g | 15 g | 160 kcal |
| Peanut butter | 2 tbsp | 16 g | 188 kcal |
| Salmon | 100 g | 13 g | 208 kcal |
| Whole egg | 1 large | 5 g | 78 kcal |
| Cheddar cheese | 30 g | 9 g | 120 kcal |
Why the floor exists
- Hormone production. Sex hormone synthesis depends on adequate dietary fat, and very low intakes are associated with disruption in both sexes.
- Vitamin absorption. Vitamins A, D, E and K require fat to be absorbed. A very low fat meal reduces uptake from the same food.
- Essential fatty acids. Linoleic and alpha-linolenic acid cannot be produced by the body and must come from food.
- Satiety and palatability. Extremely low fat diets are difficult to sustain, which is a practical failure mode even when the theory is sound.
Frequently asked questions
How much fat should I eat per day?
Is low fat dieting healthy?
Does eating fat make you fat?
Which fats should I prioritise?
Sources
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids. 2005.
- Mensink RP et al. Effects of dietary fatty acids on serum lipids. American Journal of Clinical Nutrition, 2003.
- NIH Office of Dietary Supplements. Omega-3 Fatty Acids fact sheet. ods.od.nih.gov
- National Institutes of Health, Office of Dietary Supplements. Nutrient fact sheets. ods.od.nih.gov
- NHS. Nutrition and health guidance. nhs.uk
- US Departments of Agriculture and Health and Human Services. Dietary Guidelines for Americans, 2025-2030. dietaryguidelines.gov
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General information, not medical advice. Consult a qualified professional before changing your diet, especially with a medical condition.