Fat Intake Calculator
Calculate your daily fat requirements based on body composition, activity level, and health goals using the Mifflin-St Jeor equation.
Enter your age, weight, height, gender, activity level, and health goal to get personalized daily fat intake recommendations.
Fat Intake Calculator
Calculate your daily fat requirements based on body composition, activity level, and health goals using the Mifflin-St Jeor equation.
Fat intake calculation examples
These examples show how BMR, TDEE, and fat targets change with different inputs.
| Profile | Daily fat target | Notes |
|---|---|---|
| Male, 30 yrs, 70 kg, 175 cm, moderately active, maintenance | 71 g fat/day (~2,556 kcal TDEE) | About 25% of calories from fat; standard maintenance recommendation. |
| Female, 28 yrs, 60 kg, 165 cm, lightly active, weight loss | 41 g fat/day (~1,829 kcal TDEE) | 20% of calories from fat to support a caloric deficit while preserving hormonal health. |
| Male, 25 yrs, 80 kg, 180 cm, very active, performance | 87 g fat/day (~3,114 kcal TDEE) | 25% of a high TDEE; supports recovery and hormone production for intense training. |
| Female, 35 yrs, 65 kg, 160 cm, moderately active, ketogenic | 158 g fat/day (~2,028 kcal TDEE) | Ketogenic setting assigns 70% of calories to fat; not suitable without medical supervision for most people. |
About the Fat Intake Calculator
Dietary fat is one of the three macronutrients alongside carbohydrates and protein, and despite decades of misrepresentation in popular culture, it is essential for human health. Fat provides 9 kilocalories per gram — more than double the caloric density of carbohydrates or protein — making it the body's most energy-dense fuel. It is the primary component of cell membranes, serves as a carrier for the fat-soluble vitamins A, D, E, and K, and provides the raw material for steroid hormones including testosterone, estrogen, and cortisol. Adequate dietary fat is also required for the absorption of carotenoids and other antioxidants found in vegetables.
This calculator uses the Mifflin-St Jeor equation, developed in 1990 and considered the most accurate formula for estimating basal metabolic rate (BMR) in healthy adults. For men the formula is BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5; for women it is the same except the final constant is −161 instead of +5. BMR is then multiplied by an activity factor to yield Total Daily Energy Expenditure (TDEE): sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), or extremely active (×1.9).
The Dietary Guidelines for Americans and the World Health Organization recommend that 20–35% of total calories come from fat for most healthy adults. Saturated fat should account for less than 10% of calories for cardiovascular health. This calculator distributes fat targets by health goal: weight loss uses approximately 20% of calories from fat; maintenance and performance use 25%; weight gain uses 30%; a ketogenic approach uses 70%. These percentages are divided by 9 (calories per gram of fat) to arrive at gram-based targets.
Not all fats carry equal health implications. Monounsaturated fatty acids — found in olive oil, avocados, and most nuts — improve LDL-to-HDL cholesterol ratios and are consistently associated with reduced cardiovascular risk. Polyunsaturated fatty acids, including the essential omega-3 (alpha-linolenic acid, EPA, DHA) and omega-6 (linoleic acid) families, support brain function, reduce inflammation, and are required for structural integrity of every cell membrane. Omega-3 fatty acids in particular have robust evidence for reducing triglycerides, supporting cognitive health, and attenuating the inflammatory responses associated with chronic diseases.
Saturated fat, found primarily in animal products and tropical oils, raises LDL cholesterol when consumed in excess, increasing cardiovascular risk. Trans fats — mostly artificial fats produced through partial hydrogenation — raise LDL while lowering HDL and have been largely removed from food supplies due to their unequivocal harm. The recommendations generated by this calculator are evidence-based starting points. Individual responses to dietary fat vary with genetics, gut microbiome, and overall dietary pattern, so periodic reassessment in consultation with a dietitian or physician is advisable, especially for those with metabolic conditions.
How to use the Fat Intake Calculator
- Enter your age in years, body weight in kilograms, and height in centimeters.
- Select your biological sex (used by the Mifflin-St Jeor formula for BMR accuracy).
- Choose your typical activity level from the five options ranging from sedentary to extremely active.
- Select the health goal that best matches your current objective — weight loss, maintenance, gain, performance, or ketogenic.
- Click Calculate Fat Intake to see your BMR, TDEE, total daily fat in grams, and your saturated fat limit.
Fat Intake Calculator FAQ
How much fat should I eat per day?
For most adults the Dietary Guidelines recommend that 20–35% of total daily calories come from fat. At a typical maintenance intake of 2,000 kcal that equals roughly 44–78 grams of fat per day. Your personal target depends on your calorie needs, health status, and dietary goals, which is why this calculator personalizes the recommendation to your profile.
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation estimates your basal metabolic rate — the calories your body needs at complete rest. It uses weight, height, age, and sex as inputs and is widely considered the most accurate BMR formula for healthy adults. Multiplying BMR by an activity factor gives your total daily energy expenditure (TDEE), from which macronutrient targets are derived.
Is dietary fat bad for heart health?
The relationship between dietary fat and heart health depends heavily on fat type. Unsaturated fats from plant and marine sources are heart-protective. Saturated fat in excess raises LDL cholesterol and increases cardiovascular risk, which is why guidelines cap it at under 10% of calories. Trans fats are harmful at any level and should be avoided entirely.
What are the best sources of healthy fat?
Excellent sources of healthy fats include extra-virgin olive oil (monounsaturated), fatty fish such as salmon and sardines (omega-3 polyunsaturated), avocados (monounsaturated), walnuts and flaxseeds (plant omega-3), and almonds and cashews (mixed unsaturated). Limiting butter, full-fat dairy, and processed meats helps keep saturated fat within guidelines.
What is a ketogenic fat intake?
A ketogenic diet derives roughly 65–75% of calories from fat, 20–30% from protein, and only 5–10% from carbohydrates. This induces ketosis — a metabolic state in which the liver produces ketone bodies as an alternative fuel. The ketogenic setting in this calculator assigns 70% of TDEE to fat, but this approach should be undertaken with medical guidance, especially for those with diabetes or liver conditions.
How often should I recalculate my fat intake?
Recalculate whenever your weight changes by more than 3–5 kg, your activity level changes, or your health goals shift. Pregnancy, aging, and significant muscle gain also alter caloric needs and fat targets. Many people find it helpful to review their macronutrient targets every 8–12 weeks as part of a broader nutritional check-in.