Calorie calculator
Find out how many calories you burn a day and how much to eat to lose weight, stay the same or build muscle. It uses the same formula and safety limits as your MuscleOG plan.
How this calculator works
1. Your resting burn (BMR). We use the Mifflin–St Jeor equation (Mifflin et al., American Journal of Clinical Nutrition, 1990), the formula most dietitians use for healthy adults:
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
2. Your daily burn (maintenance). We multiply your BMR by an activity factor: 1.35 if you mostly sit, 1.5 if you are on your feet part of the day, 1.65 if you have an active job or walk a lot. This roughly includes your workouts.
3. Your targets.
- Lose weight: about 450 calories a day below maintenance. That is roughly 0.4 kg (1 lb) a week, a pace most people can keep up without losing much muscle.
- Build muscle: about 250 calories above maintenance, enough to support growth without adding much fat.
- Safety limits: we never suggest less than 1,200 calories a day for women or 1,500 for men, no deficit if your BMI is under 20, and a small surplus if it is under 18.5.
4. Protein. 1.6 g per kg of bodyweight a day when losing weight or maintaining, 2 g per kg when building muscle. Above a BMI of 25 we use the weight for a BMI of 25 instead, because extra body fat does not raise how much protein you need.
How accurate is it?
Any formula is an estimate. For most people the real number is within about 10% of the result, either way. The best check is your own scale: eat at your target for 2–3 weeks, look at the trend of your morning weight, and adjust by 100–200 calories if it is not moving the way you want.
Who should not use it
This calculator is for healthy adults. It is not suitable if you are pregnant or breastfeeding, under 18, an elite athlete, or have a medical condition that affects your weight or diet. In those cases, ask your doctor or a registered dietitian.
Common questions
Why is my result different from my fitness watch?
Watches estimate your activity from heart rate and movement and often overestimate exercise calories. Use either number as a starting point and adjust from your real weight trend.
How many calories should I eat to lose 1 kg a week?
Around 1,100 calories a day below maintenance. That is too aggressive for most people and makes muscle loss more likely. A loss of about 0.5–1% of your bodyweight a week is a more sustainable pace.
Do I need to count calories to lose weight?
No, but knowing your target helps you choose portions. Your MuscleOG plan turns it into simple meal ideas.
General fitness information, not medical advice. Check with your doctor before starting if you have a health condition, an injury or are pregnant, and stop if an exercise causes pain.