One of the biggest mistakes beginners make on keto is not calculating their macros properly. Eating "low carb" isn't enough — you need to know your exact targets for fat, protein, and carbohydrates based on your body and your goals.
Here's how to do it correctly.
Step 1: Calculate Your TDEE (Total Daily Energy Expenditure)
Your TDEE is how many calories your body burns in a day. This is your starting point.
Use this formula (Mifflin-St Jeor):
For men:
TDEE = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
For women:
TDEE = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Then multiply by your activity level:
- Sedentary (desk job, no exercise): × 1.2
- Lightly active (1–3 days/week exercise): × 1.375
- Moderately active (3–5 days/week): × 1.55
- Very active (6–7 days/week): × 1.725
Example: 35-year-old woman, 70kg, 165cm, moderately active
TDEE = (10×70) + (6.25×165) − (5×35) − 161 = 1,461 × 1.55 = 2,265 calories
Step 2: Set Your Calorie Goal
Based on your goal:
| Goal | Calorie Adjustment | |---|---| | Lose weight | TDEE − 20% (deficit) | | Maintain weight | TDEE (no change) | | Gain muscle | TDEE + 10% (surplus) |
Example continued: Weight loss goal → 2,265 × 0.80 = 1,812 calories/day
Step 3: Calculate Your Protein Target
Protein is the most important macro to get right on keto.
Formula: 0.7–1.0g of protein per pound of lean body mass
To find lean body mass:
- Estimate your body fat % (use a scale, calipers, or visual guide)
Lean mass = Total weight × (1 − body fat %)
Example: 154 lbs (70kg) with 30% body fat
- Lean mass = 154 × 0.70 = 108 lbs lean mass
- Protein target = 108 × 0.8 = 86g protein/day
- Calories from protein = 86 × 4 = 344 calories
Step 4: Set Your Carb Limit
This is simple: 20g net carbs per day for most people starting keto.
Some people can stay in ketosis at 30–50g net carbs once fat-adapted (usually after 3–6 months), but start at 20g to ensure you achieve ketosis.
- Net carbs = Total carbs − Fiber − Sugar alcohols
- 20g net carbs = 80 calories from carbs
Step 5: Fill the Rest With Fat
Fat fills the remaining calories.
Formula: Fat calories = Total calories − Protein calories − Carb calories
Example continued:
- Total: 1,812 calories
- Protein: 344 calories (86g)
- Carbs: 80 calories (20g)
- Fat: 1,812 − 344 − 80 = 1,388 calories = 154g fat
Your Final Keto Macros (Example)
| Macro | Grams | Calories | % of Total | |---|---|---|---| | Fat | 154g | 1,388 | 77% | | Protein | 86g | 344 | 19% | | Net Carbs | 20g | 80 | 4% | | Total | | 1,812 | 100% |
Common Mistakes in Keto Macro Calculation
1. Using total weight instead of lean mass for protein This can lead to over-eating protein, which may kick you out of ketosis through gluconeogenesis.
2. Not adjusting as you lose weight Your TDEE changes as you lose weight. Recalculate every 10–15 lbs lost.
3. Ignoring fiber Fiber doesn't count toward your 20g limit. A salad with 8g total carbs and 4g fiber = only 4g net carbs.
4. Forgetting calories in fat Fat has 9 calories per gram (vs 4 for protein and carbs). It adds up fast — don't eat unlimited fat thinking it doesn't matter.
5. Not adjusting for exercise If you work out hard, you may need to increase your protein and total calories to avoid muscle loss.
The Easier Way: Let AI Calculate For You
Calculating macros manually is doable but tedious — and it requires re-doing the math as your weight changes.
KetoCoach automatically:
- Calculates your personal TDEE
- Sets your protein based on lean body mass
- Adjusts macros as you progress
- Tracks your daily intake against your targets
- Alerts you when you're off track
Get your free custom keto macros →
Quick Reference Keto Macro Ranges
| Body Weight | Protein | Fat | Net Carbs | |---|---|---|---| | 120–140 lbs | 65–85g | 100–130g | 20g | | 140–170 lbs | 80–110g | 120–160g | 20g | | 170–200 lbs | 95–130g | 140–185g | 20g | | 200–230 lbs | 110–150g | 160–210g | 20g | | 230+ lbs | 125–170g | 180–240g | 20g |
Based on moderate activity level and 20% calorie deficit for weight loss.
The most important thing is to start. Use these numbers as your starting point, track for 2 weeks, and adjust based on your results. Your body will tell you what's working.