Example Data Table
These examples show common surplus choices and projected outcomes.
| Person Type |
Maintenance Calories |
Daily Surplus |
Target Intake |
Expected Weekly Gain |
| Light beginner |
2,100 kcal |
250 kcal |
2,350 kcal |
0.23 kg / 0.50 lb |
| Moderate trainer |
2,650 kcal |
400 kcal |
3,050 kcal |
0.36 kg / 0.80 lb |
| Hard gainer |
3,000 kcal |
600 kcal |
3,600 kcal |
0.55 kg / 1.20 lb |
Formula Used
The calculator first estimates basal metabolic rate. Mifflin-St Jeor uses weight, height, age, and sex.
Revised Harris-Benedict uses a similar structure with different coefficients.
Katch-McArdle uses lean body mass, so body fat percentage is required.
TDEE = BMR × Activity Factor + Extra Training Calories
Daily Surplus = Weekly Gain in kg × 7,700 ÷ 7
Target Calories = TDEE + Daily Surplus
The physics view converts food energy into kilojoules. One food calorie equals about 4.184 kilojoules.
The calculator uses 7,700 kcal as a practical estimate for one kilogram of body mass change.
How to Use This Calculator
- Enter your age, sex, height, and current weight.
- Select a BMR formula. Use Katch-McArdle only when body fat is known.
- Choose the activity level that best describes your average week.
- Add extra training calories when your selected activity does not include them.
- Enter your desired weekly gain, or enter a manual daily surplus.
- Set the plan length and optional target weight.
- Adjust protein, fat, and meal settings.
- Press calculate, then export the result as CSV or PDF.
Understanding Calorie Weight Gain Planning
Energy Balance Matters
Weight gain starts with energy balance. Your body uses energy every day.
It uses energy for breathing, movement, digestion, training, and recovery.
When intake stays above total daily expenditure, stored mass can increase.
This calculator estimates that gap and turns it into a practical target.
Why Physics Is Useful
Food energy can be viewed like any other energy input.
Calories enter the body through meals and drinks.
Activity, heat production, and tissue repair use that energy.
A surplus means more energy enters than leaves.
The calculator also shows kilojoules and megajoules.
That makes the result easier to compare with physical energy units.
Choosing a Surplus
A small surplus usually gives slower gain.
It may help reduce unwanted fat gain.
A large surplus may raise body weight faster.
It can also feel harder to digest.
Many users start with a moderate surplus.
Then they adjust after two or three weeks.
Scale trends are more useful than one daily weigh-in.
Macros and Practical Meals
Calories are only one part of the plan.
Protein supports muscle repair and growth.
Fat supports hormones and calorie density.
Carbohydrates fill the remaining energy target.
The meal estimate divides calories across the day.
This helps with planning breakfast, lunch, dinner, and snacks.
Tracking Progress
Use the result as a starting model.
Real life can differ from equations.
Appetite, sleep, training quality, and daily movement can change results.
Review body weight averages each week.
If weight does not rise, increase intake slightly.
If weight rises too quickly, reduce the surplus.
Consistent tracking makes the calculator more accurate over time.
FAQs
1. What does this calculator estimate?
It estimates maintenance calories, daily surplus, target intake, projected gain, energy units, and macro targets for weight gain planning.
2. Which BMR formula should I choose?
Mifflin-St Jeor is a strong default. Harris-Benedict is another common estimate. Use Katch-McArdle when you know body fat percentage.
3. What is a calorie surplus?
A calorie surplus means you eat more energy than your body uses. The extra energy supports weight gain over time.
4. Why use 7,700 kcal per kilogram?
It is a practical planning estimate for body mass change. Actual results vary with water, glycogen, digestion, and training response.
5. Can I use pounds instead of kilograms?
Yes. The form accepts weight and weekly gain in pounds or kilograms. Results show both units for easier comparison.
6. Why does the calculator show macros?
Macros help convert calories into daily food targets. Protein, fat, and carbohydrates make the calorie plan easier to follow.
7. What if my weight does not increase?
Track weekly averages first. If weight stays flat for two weeks, add a small calorie increase and review activity changes.
8. Is this calculator medical advice?
No. It is an educational planning tool. People with medical conditions should consult a qualified health professional before major diet changes.