What is a calorie surplus?
A surplus means average intake exceeds expenditure. How added energy affects fat, muscle, and other tissue depends on training, protein intake, genetics, health, and the size and duration of the surplus.
Adding a surplus to maintenance
The tool estimates TDEE from Mifflin–St Jeor and activity, then adds your chosen 100–500 kcal/day surplus, defaulting to 250. The rough weight-change illustration uses a fixed 7,700 kcal/kg equivalent; tissue gain is more complex than this arithmetic.
How to use this calculator
- 1Enter your current measurements, usual activity, and a higher target weight.
- 2Choose a daily surplus to compare.
- 3Calculate and review the intake estimate alongside training and weight trends.
Understanding your result
The surplus is an addition to the estimated maintenance level. Assess the trend over time and consider strength, performance, appetite, and overall nutrition. Unintentional weight loss or difficulty maintaining weight deserves clinical evaluation rather than only a larger calorie target.
Assumptions & limitations
- The fixed conversion cannot predict muscle gain, fat gain, or an exact goal date.
- This tool is not a refeeding plan or guidance for eating-disorder recovery or medically significant underweight.
Frequently asked questions
Will all of the estimated gain be muscle?+
No. Weight gain can include fat, muscle, water, and glycogen. A calorie surplus alone does not determine how much muscle is built.
Does a larger surplus build muscle faster?+
Not necessarily. Muscle growth is limited by training response and other factors; extra energy can add more fat without a proportional muscle benefit.
Why did my weight jump after increasing food?+
More food in the digestive tract, carbohydrate-associated glycogen and water, and sodium changes can increase scale weight before much tissue is gained.
Should I use this after unexplained weight loss?+
A clinician should assess unexplained loss or persistent difficulty maintaining weight. The calculator cannot identify a cause or establish an appropriate treatment plan.
