Weight Gain Calculator
Enter your sex, age, height, weight, activity level and the weight you want to reach. You get your daily surplus, your bulking calorie target, the weeks it takes, a projected date, and a protein range to eat alongside it.
Your daily bulking calories
3,056calories a day+500
2,556 maintenance calories plus a 500 calorie surplus.
- Maintenance 2,556
- Surplus +500
Your timeline
Protein while bulking
112 - 154g protein a day
1.6 to 2.2 g per kg of body weight. Muscle gain flattens out near 1.6 g per kg in the 2018 Morton meta-analysis, so the top of the band is a cushion rather than a requirement.
Lean vs standard pace
| Pace | Surplus | Weeks | Goal date |
|---|---|---|---|
| Lean 0.25 kg | +250 | 20 | Jan 22, 2027 |
| Standard 0.5 kg | +500 | 10 | Nov 13, 2026 |
Lean adds about a quarter kilo a week and keeps fat gain low. Standard is twice as fast and brings more fat with it. Switch the pace above to change the plan.
An estimate from the Mifflin-St Jeor equation. Weigh yourself weekly, and if the scale has not moved in two weeks, add 150 to 200 calories a day.
How the number is worked out
The calculator starts with your maintenance calories: the Mifflin-St Jeor equation for your resting burn, multiplied by an activity factor from 1.2 for a desk job to 1.9 for physical work or twice-daily training. A moderately active 30 year old man at 70 kg and 175 cm lands at about 2,556 calories a day.
Then it adds a surplus. A kilogram of body tissue carries roughly 7,700 calories, adjusted down a little because part of a healthy gain is muscle and glycogen rather than fat. A lean bulk adds 250 calories a day for close to 0.25 kg a week. A standard bulk adds 500 for close to 0.5 kg a week. The gap between your weight and your target, divided by the weekly rate, gives the number of weeks and the date. The man above aiming for 78 kg needs 32 weeks on lean or 16 on standard.
Protein comes out at 1.6 to 2.2 g per kilogram of current body weight. The 2018 Morton meta-analysis in the British Journal of Sports Medicine pooled 49 studies and found extra protein stopped adding muscle past about 1.6 g per kg. The top of the band is headroom for hard training days, not a target.
Bulking calories
Maintenance plus surplus is the number you eat today. Weigh in three or four mornings a week and judge the weekly average, because a single morning swings by a kilogram on water alone. Recalculate every 4 to 5 kg. The surplus that worked at 70 kg is close to maintenance at 76 kg, and that is the usual reason a bulk stalls in month three.
Calorie surplus for a lean bulk
A trained adult adds something like 0.2 to 0.5 kg of muscle in a good month, which is why the lean option sits at 250 calories. Eating 1,000 over maintenance does not build muscle four times faster. The extra lands as fat and has to come off again later. If you are new to lifting or coming back after a long break, the standard pace suits you better for the first few months. The muscle gain guide covers what those meals look like.
Weight gain for hard gainers
People who say they cannot gain weight usually eat 400 to 700 calories a day less than they think, and the gap only shows up in a full week of logs. Big appetite days get remembered, low days do not. Drink some of your calories, add a tablespoon of olive oil to a meal for 120 calories, and set a floor for the low days rather than trying to make up for them later.
Track it in NutriScan
The calculator gives you one number. Whether the plan works is decided at dinner on a Tuesday. NutriScan logs a meal from a photo, your voice, a barcode or a typed line, and adds calories and protein against the bulking target you set here, so you can see how much is left before the last meal rather than after it.
The free plan gives you 5 photo scans a week plus unlimited manual logging, water tracking and the fasting timer. Premium removes the scan cap and costs about $59 a year.
Frequently asked questions
How many calories do I need to eat to gain weight?
Take your maintenance calories and add a surplus. A 250 calorie surplus adds roughly 0.25 kg a week, a 500 calorie surplus roughly 0.5 kg. For a 70 kg moderately active man whose maintenance is about 2,550 calories, that is 2,800 calories a day on a lean bulk or 3,050 on a standard one.
What is a good calorie surplus for a lean bulk?
Around 250 calories a day, or about 10 percent over maintenance. That pace adds close to 0.25 kg a week, which is near the ceiling for how fast an adult who already trains can build muscle. A bigger surplus does not speed muscle growth much, it mostly adds fat.
How fast should I gain weight?
0.25 to 0.5 percent of your body weight a week suits most people. Beginners and anyone coming back after a long break can sit at the top of that range. If you have trained hard for years, stay near the bottom, because the muscle you can add in a month is limited and the rest lands as fat.
How much protein do I need while bulking?
1.6 to 2.2 g per kg of body weight a day. The 2018 Morton meta-analysis in the British Journal of Sports Medicine found gains in muscle and strength stop improving past roughly 1.6 g per kg, so the top of the range is a cushion for days when you eat less.
Why am I not gaining weight even though I eat a lot?
Almost always because the weekly average is lower than it feels. Big appetite days get remembered and low days do not. Log everything for one honest week, including drinks and cooking oil, then compare that average with the target here. If the scale has not moved in two weeks, add 150 to 200 calories a day and check again.
Related calculators
Your inputs are saved between these pages, so each one opens with your numbers filled in.
- TDEE calculator for maintenance calories at every activity level
- Weight loss calculator for a daily target and a projected date for a goal weight
- Protein intake calculator for daily grams and a per-meal split
- Calories burned calculator for one workout or a day of steps
- Weight gain diet plan app for what a week of surplus tracking looks like