To gain weight, you need to eat more calories than your body uses. This calculator works out your maintenance calories, then adds a small amount based on how fast you want to gain.
How many calories should I eat to gain weight?
At our paces, about 100 to 300 calories a day more than your maintenance. That works out at roughly 0.1 to 0.25 kg a week. The NHS suggests adults could add around 300 to 500 extra calories a day, and gain weight gradually.
The Ori app starts at the lower end and adjusts from there. A smaller surplus is easier to fine-tune. If your weekly average hasn't moved after a few weeks, add a little more.
How do you calculate calories to gain weight?
It takes three steps.
- Work out your maintenance calories: what you burn in a day. Our maintenance calorie calculator shows how.
- Pick a pace. A rough rule says a kilo of body weight holds about 7,700 calories. So gaining 0.15 kg a week needs about 165 extra calories a day (0.15 × 7,700 ÷ 7).
- Add that to your maintenance.
Here's an example. A 25-year-old man who is 178 cm tall, weighs 60 kg and exercises 1 to 3 days a week has a maintenance of about 2,200 calories a day. At the steady pace, he'd eat about 2,350.
The 7,700 rule is only a guide, and it was worked out for weight loss. Treat your first target as a starting point and let your weekly average guide the next change.
How fast should you gain weight?
Gradually. The NHS advises gaining weight gradually, and the Ori app keeps to 0.25 kg a week or less, as does this calculator.
Your weight goes up and down every day with water, salt and food, so a single heavy day doesn't mean much. Compare weekly averages instead. Our guide on why your weight fluctuates so much explains why.
Why am I not gaining weight?
Usually because your surplus is smaller than you think. You may burn more than you estimated, eat less at other meals without noticing, or move more when you eat more. Our guide on why you're not gaining weight in a calorie surplus goes through what to check, and our comparison of apps for gaining weight may help with tracking.
Who shouldn't use this calculator?
It's for adults. If you're under 18, pregnant or breastfeeding, or have or have had an eating disorder, please speak to your GP or a dietitian instead.
The NHS says to speak to a GP if you've lost weight suddenly, or without changing your diet or exercise routine, as it could be a sign of an underlying health condition.
A gentle safety note
This calculator gives a general estimate for healthy adults. It is not medical advice. Ori supports general wellness and is not medical care.
Read Ori's Health Disclaimer