How many grams of fat should I eat per day?

The IOM AMDR is 20–35% of calories. The exact gram count depends on your daily calorie target — at 2,000 kcal/day that's roughly 44–78 g.

Why divide kcal by 9 to get grams?

Dietary fat provides about 9 kilocalories per gram (Atwater factor). So 600 kcal from fat is ≈ 67 g.

What counts as saturated fat?

Saturated fats are mostly solid at room temperature: butter, lard, full-fat dairy, fatty cuts of red meat, coconut and palm oil. The AHA suggests keeping these under about 10% of total calories.

Are low-fat diets healthier?

Below 20% of calories from fat for extended periods can impair absorption of fat-soluble vitamins (A, D, E, K) and may reduce satiety. Most experts recommend staying within the 20–35% AMDR unless under medical supervision.

Does this tool store my data?

No. Inputs stay in your browser and are cleared when you close the tab.

Is the fat calculator free?

Yes — completely free, no signup or limits.

Fat Calculator

Calculate daily fat grams and saturated vs unsaturated split from your calorie target.

Written by Golam Rabbani, Founder & Lead Engineer — Last updated 2026-05-01

This interactive tool requires JavaScript. Read the formula and worked example below; you can compute the result by hand.

How to use this fat calculator

Enter your total daily calorie target.
Drag the slider to set your target fat percentage (15–40%).
Watch the AMDR note update so you know whether the chosen % is inside the IOM guideline range.
Press Calculate to see daily fat in grams plus the saturated/unsaturated split.

About this fat calculator

The fat calculator converts a daily calorie target into grams of dietary fat at the percentage you choose, then breaks the total into a saturated cap and an unsaturated target. It uses the Atwater factor of 9 kcal per gram of fat. The slider spans 15% to 40%, comfortably covering low-fat plans through to higher-fat low-carb or keto-adjacent eating.

The recommended bands come from the Institute of Medicine's Acceptable Macronutrient Distribution Range (AMDR) for total fat, which is 20–35% of daily calories for adults, while the American Heart Association advises keeping saturated fat under about 10% of total calories. This is an estimate for informational purposes and is not a substitute for advice from a registered dietitian or qualified clinician.

For example, on 2,200 kcal/day at 30% fat: total fat = 2,200 × 0.30 / 9 ≈ 73 g; saturated cap = 2,200 × 0.10 / 9 ≈ 24 g; the remaining ≈ 49 g should come from mono- and polyunsaturated sources like olive oil, nuts, seeds, avocado, and oily fish. The tool is useful for setting daily fat targets in a tracking app and seeing how moving the slider from 20% to 35% changes both total fat and the saturated ceiling.

FAQ

How many grams of fat should I eat per day?: The IOM AMDR is 20–35% of calories. The exact gram count depends on your daily calorie target — at 2,000 kcal/day that's roughly 44–78 g.
Why divide kcal by 9 to get grams?: Dietary fat provides about 9 kilocalories per gram (Atwater factor). So 600 kcal from fat is ≈ 67 g.
What counts as saturated fat?: Saturated fats are mostly solid at room temperature: butter, lard, full-fat dairy, fatty cuts of red meat, coconut and palm oil. The AHA suggests keeping these under about 10% of total calories.
Are low-fat diets healthier?: Below 20% of calories from fat for extended periods can impair absorption of fat-soluble vitamins (A, D, E, K) and may reduce satiety. Most experts recommend staying within the 20–35% AMDR unless under medical supervision.
Does this tool store my data?: No. Inputs stay in your browser and are cleared when you close the tab.
Is the fat calculator free?: Yes — completely free, no signup or limits.