Fat Intake Calculator

How to use this calculator

1. Choose US Units or Metric Units. Switching converts figures you have already typed rather than clearing them.
2. Enter your age and select your gender.
3. Enter your height and weight.
4. Pick the activity level that best matches a typical week.
5. Press Calculate to see your total-fat range and the two limits on saturated fat.

+ Settings holds two choices most people never change: which of the three published BMR equations to use for the calorie figure, and a body fat percentage for the one that needs it. Other Units opens a converter above the calculator for anyone whose scales read in stones; it is not a third unit system, and the calculator stays on whichever system you chose.

You no longer need to bring a calorie figure with you — the calculator works it out from your own details, using the same engine as the calorie calculator, so the two always agree.

Why it asks for your body, not your calories

Every number this calculator reports is a share of the energy you actually use, so it has to know what that is. It estimates your basal metabolic rate from your age, gender, height and weight, multiplies by your activity level to get your daily Calories, and takes the recommended shares of that. Enter the same details here and in the calorie calculator and you will get the same calorie figure, because it is the same calculation.

How much fat you need

National nutrition guidelines set the Acceptable Macronutrient Distribution Range (AMDR) for fat at 20–35% of daily calories. Fat is not optional: it carries the fat-soluble vitamins A, D, E and K, supplies essential fatty acids, and supports hormone production. The range leaves room to shift fat up or down depending on how you allocate carbohydrate and protein.

The formula

Because each gram of fat supplies 9 calories, converting a percentage of calories into grams is straightforward:

Fat (g) = calories × percentage ÷ 9

• calories — your daily calorie target
• percentage — the share of calories from fat (20% to 35%)
• 9 — calories per gram of fat

The calculator reports the low end (20%) and the high end (35%) as a band, then applies the same arithmetic to the two published caps on saturated fat: under 10% of Calories in the Dietary Guidelines, and the tighter under 6% the American Heart Association recommends for people working to lower their cholesterol. Trans fat gets no row at all, because there is no recommended level of it — the guidance is simply to keep it as low as you can.

A worked example

On a 2,000-calorie day, the low end is 2,000 × 20% ÷ 9 ≈ 44 g, the midpoint is 2,000 × 27.5% ÷ 9 ≈ 61 g, and the high end is 2,000 × 35% ÷ 9 ≈ 78 g. So a fat intake anywhere from about 44 to 78 grams a day fits the guideline at this calorie level.

Where to sit in the range

• Lower end (~20%) — leaves more calories for carbohydrate, which suits higher-volume or endurance eating.
• Middle (~27.5%) — a balanced default for most people.
• Higher end (~35%) — pairs with lower-carbohydrate patterns and can aid satiety.

Quality matters as much as quantity

Within your range, favour unsaturated fats — olive and avocado oil, nuts, seeds and oily fish — which support heart health. Keep saturated fat (fatty meat, butter, full-fat dairy) moderate, and avoid artificial trans fats. The gram target is the same whatever the source, but the source is what shapes the health outcome.

Pair this with your protein target to round out a macronutrient plan. This is educational information, not medical or dietary advice.