The Weight Gain Calculator is a free tool that helps you calculate weight gain using the formula TDEE +/- calorie adjustment for the goal. Enter your values above and press Calculate to get daily calorie target instantly, with a full step-by-step breakdown.
What is the Weight Gain Calculator?
The weight gain calculator is a free online tool that helps you calculate weight gain quickly and accurately. It applies the standard formula TDEE +/- calorie adjustment for the goal to the values you enter and, when you press Calculate, displays the result together with a clear, step-by-step explanation of how the answer was reached.
How to use the Weight Gain Calculator
- Enter your details and activity.
- Pick a goal.
- See your daily calorie target.
Formula used
The weight gain calculator is based on this formula:
TDEE +/- calorie adjustment for the goalEach term in the formula corresponds to one of the inputs explained below. The calculator performs the arithmetic for you and shows every step so you can check the working by hand if you wish.
Worked example
Suppose you enter Male, 30y, 70kg, 170cm, moderate, lose. The calculator works as follows:
| Inputs | Male, 30y, 70kg, 170cm, moderate, lose |
|---|---|
| Working | TDEE - 500 |
| Result | about 2006 kcal/day |
Step-by-step calculation
- Apply the formula:
TDEE +/- calorie adjustment for the goal - Substitute your values: TDEE - 500
- Read the result: about 2006 kcal/day
Calorie adjustment for weight goals
| Goal | Daily adjustment |
|---|---|
| Maintain weight | ± 0 kcal |
| Lose ~0.5 kg/week | −500 kcal |
| Gain ~0.5 kg/week | +500 kcal |
Inputs explained
- Gender — the gender used in the calculation.
- Age (years) — the age used in the calculation.
- Weight (kg) — the weight used in the calculation.
- Height (cm) — the height used in the calculation.
- Activity — the activity used in the calculation.
- Goal — the goal used in the calculation.
Understanding your result
- Daily calorie target — the calculated daily calorie target in kcal/day.
Benefits and practical uses
The weight gain calculator saves time and removes the risk of manual errors when you need to calculate weight gain. It is useful for students, professionals and anyone who wants a fast, dependable answer. Results update the moment you press Calculate, work on any device, and can be copied or shared in a single click — and because the maths runs in your browser, your figures stay completely private.
Tips for an accurate result
- Keep all related inputs in the same units.
- Use the worked example above to confirm you are entering values in the right places.
- Review the assumptions below so the result fits your situation.
- Press Reset to clear everything and try a different scenario.
Common mistakes to avoid
- Entering values in the wrong unit (mismatched units give wrong answers).
- Leaving a required field empty — the calculator will ask you to fill it in.
- Treating the result as a diagnosis instead of a general guide.
Assumptions and limitations
- Mifflin-St Jeor; 7700 kcal is about 1 kg.
Frequently asked questions
How big a deficit is safe?
A 500 kcal/day deficit (about 0.5 kg/week) is widely considered sustainable for most adults.
How do I use the Weight Gain Calculator?
Enter your values in the fields, then press the Calculate button to see the result. Use Reset to clear the form and start again. Nothing is calculated until you click Calculate.
What formula does the Weight Gain Calculator use?
It uses the standard formula: TDEE +/- calorie adjustment for the goal. The full step-by-step working is shown with every result so you can verify it.
What information do I need to use the weight gain calculator?
You need: gender, age, weight, height, activity, goal. Sensible example values are pre-filled so you can see how it works.
Is the Weight Gain Calculator free to use?
Yes. Every DigiToolkit calculator is completely free, with no sign-up, no login and no usage limits.
Does the Weight Gain Calculator work on mobile phones?
Yes. The calculator is mobile-first and works on phones, tablets and computers in any modern browser.
Do I need to install an app?
No. The weight gain calculator runs directly in your web browser — there is nothing to download or install.
Is my data private when I use this calculator?
Yes. All calculations run inside your browser. The numbers you enter are never uploaded to a server or shared with anyone.
How accurate is the Weight Gain Calculator?
It uses the generally accepted formula for weight gain and computes to several decimal places. Results are accurate for the assumptions listed on this page.
Can I copy or share my result?
Yes. After calculating, use the Copy button to copy the result, or Share to copy the page link.
Why is nothing showing until I press Calculate?
By design, the calculator only computes when you press Calculate, so you can finish entering all your values first. Press Reset any time to clear everything.
What units does the Weight Gain Calculator use?
It works with cm, kg, years. Keep your inputs in consistent units for an accurate result.