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About this tool
Net carb allowance, protein and fat targets for each Atkins phase — Induction, Balancing, Fine-Tuning and Lifetime Maintenance.
This calculator turns the four published Atkins phases into a daily macro target: the net carb allowance fixed by your phase, a moderate protein amount set per kilogram of body weight, and dietary fat filling the remaining calories. Energy needs come from the Mifflin-St Jeor equation multiplied by an activity factor, so the numbers move with your size and training load rather than a one-size-fits-all template. It is built for anyone running Atkins 20 or Atkins 40 who wants to know exactly how many net carbs today allows and what the rest of the plate should look like.
Open Atkins Phase Macro Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Applies the real 20 g / +5 g / +10 g weekly steps instead of a single fixed number.
Fat grams are whatever is left after carbs and protein hit your calorie target.
Warns when fat drops under 20% of calories, which usually means protein is set too high.
20 g of net carbs a day, held for a minimum of two weeks. Atkins asks that 12–15 g of that 20 come from foundation vegetables such as spinach, broccoli, cauliflower and salad leaves, leaving only about 5–8 g for everything else.
Net carbs are total carbohydrate minus fibre minus sugar alcohols. Fibre and most polyols are not absorbed as glucose, so they have little effect on blood sugar — that is why a 100 g serving of broccoli with 7 g total carbs and 3 g fibre counts as 4 g net carbs.
Phase 2 starts at 25 g and adds 5 g a day each week while weight loss continues, up to about 50 g. Phase 3 starts at 50 g and adds 10 g a week up to roughly 80 g. If the scale stalls, you drop back to the previous week's number rather than pushing higher.
Atkins is moderate-protein, not high-protein — commonly 1.2–1.6 g per kilogram of body weight, which for a 90 kg person is roughly 110–145 g a day. Going much higher squeezes fat out of the plan and makes the calorie target very hard to eat. Anyone with reduced kidney function should agree a protein level with their doctor first.
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