Calorie Surplus Calculator
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How to Use the Calorie Surplus Calculator
Enter your age and gender
Type an age between 1 and 120 and pick a gender. The gender changes the formula constant used to find your resting burn.
Set the weight unit and enter your current and target weight
Tap kg or lb on the switch, then type your current weight and the target you want to reach. The target must be higher than your current weight.
Set the height unit and enter your height
Switch between cm and ft + in. For feet and inches, fill in both boxes, keeping inches below 12.
Choose your activity level
Pick the level that matches your typical week, because it decides the multiplier applied to your resting burn.
Pick a timeframe and click Calculate
Choose how quickly you want to reach your target. The tool works back from that deadline and keeps the plan sensible.
Read your full result
See your daily intake and surplus, an estimated muscle versus fat split, a weekly weight projection, lean bulk macros, and a reality check.
A Lean, Sensible Surplus Plan - With the Muscle the Numbers Imply
A calorie surplus means eating more energy than your body burns, the energy your body needs to grow. Most surplus tools stop at one daily number and imply all of it becomes muscle, which it simply does not. This one builds a more honest plan: it sets your daily surplus target, estimates how much of the weight you gain is likely to be lean muscle versus stored fat, projects your weight week by week, lays out a lean bulk macro split that protects that muscle, and refuses to hand you a reckless figure. Enter your details and get a plan built for steady, real results.
The Mifflin-St Jeor Equation Behind the Number
This calculator finds your Basal Metabolic Rate with the Mifflin-St Jeor equation, developed in 1990 and considered the most accurate formula for the general population. For men it is 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age, plus 5. For women it is the same but minus 161. When no gender is chosen, the tool uses the midpoint. Your resting burn is multiplied by an activity factor to reach the maintenance number your surplus adds onto.
Your Daily Surplus and Intake
The headline number is your daily intake, shown with the surplus it creates above your maintenance. Since about 7,700 calories of stored energy equal one kilogram gained, the tool divides your total calorie gap by your deadline in days to find the daily surplus. The hero card keeps the intake and the surplus together so you always know the extra you are adding on top of your maintenance.
An Honest Muscle vs Fat Split
Your body can only build muscle at a limited pace, no matter how much extra you eat. This is the tool's most distinct feature: it estimates how much of your planned gain is likely to be lean muscle and how much is likely fat, based on your weekly rate of gain. At a steady pace of about 0.35 to 0.5 kilograms a week, roughly half the gain can be muscle when training and protein are on point. Push the pace higher and the share of fat climbs, which the split shows and the note explains. Seeing this number keeps expectations realistic and steers you toward a leaner outcome.
A Steady Weight Projection
Instead of only a finish line, the result shows your estimated weight at a series of checkpoints across the journey, labelled by week. From your current weight it applies your steady weekly gain and draws a simple path to your target. You can glance at any checkpoint and see roughly where you should be, which makes the plan easier to follow and adjust along the way.
Progress at a Glance
A compact grid sums up the essentials: your maintenance calories, the total weight left to gain, the exact daily surplus, and the estimated time it will take. Each card pairs with a short note so the line between your current weight, your daily surplus, and your finish line stays visible in one quick scan.
A Lean Bulk Macro Split
Where the surplus calories come from decides how much becomes muscle. The result splits your intake into grams of protein, carbs, and fat tuned for a lean bulk. Protein sits around 1.8 grams per kilogram of body weight to fuel muscle repair, carbs power your training sessions, and healthy fats support your hormones. Each macro shows its grams and calories so you can plan real food around the numbers.
A Simple Meal Day
A large surplus can be hard to eat if you try to do it in one sitting, so the result divides your intake into three meals at a target per meal. Spreading protein across the day also keeps muscle repair running constantly, which supports the lean outcome the macro split aims for.
Your Energy Picture and a Formula Check
The result shows your BMR and your maintenance TDEE, alongside a Harris-Benedict estimate and your goal intake. Seeing all four together makes it obvious why a heavier, more active person needs more food to gain. A caption states how far the two formulas sit apart, a reminder to treat your numbers as a range and adjust with real progress.
A Reality Check on Your Target
Using your height, the tool computes your healthy weight range from body mass index cut-offs of 18.5 and 24.9 and tells you whether your target sits inside it. A person 1.75 m tall sees a healthy band of roughly 56.7 to 76.3 kg. If your target climbs well above the band, the note flags that a large surplus mostly adds fat, so staying closer to the healthy range is usually wisest.
A Cap That Keeps It Sensible
Extreme surpluses do not build muscle any faster, so the tool caps your intake at 5,000 calories. If your plan would exceed that, it holds your intake at the cap and recalculates the real time needed, then explains in an orange guide why the slower path protects your lean outcome. Your safety and your waistline come before an aggressive deadline.
This calculator is for informational purposes only and is not medical advice. Always consult a qualified healthcare professional about your nutrition and health.