Fat Intake Calculator

Find how many grams of dietary fat to eat per day, based on your calorie needs and the 20–35% Acceptable Macronutrient Distribution Range.

Sex
Height cm
ft in
Activity level
  • Sedentary — little or no exercise
  • Light — exercise 1–3 days/week
  • Moderate — exercise 3–5 days/week
  • Active — exercise 6–7 days/week
  • Very active — hard exercise or physical job
Goal
  • Maintain weight
  • Lose weight (−0.5 kg/week)
  • Gain weight (+0.5 kg/week)
Calorie formula
  • Mifflin-St Jeor (recommended)
  • Harris-Benedict
  • Katch-McArdle (uses body fat)
Recommended fat —g/day
Enter your details
Daily calorie target—
Recommended range—
Share of total calories—
Saturated fat (max)—

From your calorie target and the IOM Acceptable Macronutrient Distribution Range for fat.

Dietary fat is essential: it provides energy, helps you absorb vitamins A, D, E, and K, and supports hormone production. Because your fat target is a share of your total calories, this calculator estimates your energy needs first and then converts them into a daily fat range in grams.

How your fat target is calculated

  1. Calories. Your daily energy needs come from the Mifflin-St Jeor equation, your activity level, and your goal.

  2. The range. The Institute of Medicine’s Acceptable Macronutrient Distribution Range (AMDR) for fat is 20–35% of total calories. Fat provides 9 kcal per gram, so:

    fat (g) = calories × 0.20…0.35 ÷ 9

Worked example

On a 2,000-calorie day:

  • Low end: 2,000 × 0.20 ÷ 9 ≈ 44 g
  • High end: 2,000 × 0.35 ÷ 9 ≈ 78 g

Alongside your total fat range, the calculator also shows a saturated-fat ceiling — the Dietary Guidelines cap saturated fat at under 10% of daily calories, and the American Heart Association suggests under 7% for heart health.

Quality matters as much as quantity

Hitting your gram target is only part of the goal — the kind of fat matters:

  • Favour unsaturated fats — olive and canola oil, avocado, nuts, seeds, and oily fish.
  • Limit saturated fat to under about 10% of daily calories (fatty meats, butter, full-fat dairy, many baked goods).
  • Avoid trans fats from partially hydrogenated oils wherever possible.

The American Heart Association recommends replacing saturated fat with unsaturated fat rather than with refined carbohydrate.

Frequently asked questions

How many grams of fat should I eat per day?

The Institute of Medicine recommends 20–35% of your calories come from fat. On a 2,000-calorie day that's about 44–78 g. This calculator estimates your calorie needs first, then applies that range to give your grams.

Isn't dietary fat bad for you?

No — fat is essential. It supplies energy, carries fat-soluble vitamins (A, D, E, K), and supports hormones. What matters most is the type: favour unsaturated fats from olive oil, nuts, seeds, and fish, and limit saturated fat to under about 10% of calories.

Why does the calculator ask for my height, age, and activity?

Your fat target is a share of your total calories, and calories depend on your body size, age, sex, and activity. The tool works out your daily energy needs with the Mifflin-St Jeor equation, then takes 20–35% of that as fat.

What's the least fat I should eat?

Going much below about 20% of calories makes it hard to absorb fat-soluble vitamins and get enough essential fatty acids. Very-low-fat diets are rarely necessary; the 20–35% range suits most people.

References