On keto, fat is the lever you pull to hit your calories once protein and carbs are set. Put your targets in (the macro calculator gives you all three) and this tells you the fat to fill the rest, in grams and in real portions.
On keto, fat is the adjustable part of your plate. Protein is set by your body weight to protect muscle, net carbs sit at a fixed limit to keep you in ketosis, and fat takes up whatever calories are left. That is why this works backwards from a calorie target rather than a fixed percentage: change your calories, protein or carbs and the fat number moves with them. Eat towards it on days you are hungry, ease off it on days you are not, and let the scale and tape measure over a few weeks tell you whether the total is right. For the full picture of how the three macros fit together, see keto macros explained, and if you are still finding your feet the first 30 days guide covers the rest.
How much fat should I eat on keto?
Fat fills the calories left after protein and net carbs. On a 1800 calorie day with 120g protein and 20g net carbs that is roughly 140g of fat. Enter your own numbers above to get yours.
Is fat a minimum I must eat?
No. It is the fat that fills your calorie target, not a floor. If fat loss is going well and you are not hungry, eating under it is fine; the difference comes from your own body fat.
What share of calories should be fat?
Usually somewhere around 65 to 75 percent, lower on an aggressive deficit and higher at maintenance. The percentage follows the maths, so do not chase a fixed number.
Fat grams = (calories − protein×4 − net carbs×4) ÷ 9, since protein and carbohydrate give about 4 kcal per gram and fat about 9. This is the fat that fills your calorie target, not a minimum you must eat: if you are losing fat well and not hungry, eating under it (drawing the difference from your body's own fat) is fine and expected. Eat towards protein and under your carb limit first, then use fat to manage hunger and energy. General information, not medical advice.