The cornerstone of any good fitness plan is getting your diet right, and to do that, the first thing you need to do is to determine what your daily calorie needs are.
There are a lot of different online calculators you can use to find out how many calories you should eat per day. Some of them are ok, but most calorie calculators oversimplify by only using your age, weight, and gender (and perhaps BMI).
If you are a fitness nerd like me, you will probably want to know the correct scientific way of calculating what your daily calorie needs are.
It’s a very easy 5-step process. I have used my own data in the example below to show you how I work out what my daily calorie needs are.
How to calculate your daily calorie needs
You can calculate your daily “maintenance calories” by following these easy steps:
Step 1: Find your current body weight in kilograms (if you live in the US, just divide your current weight in pounds by 2.2 to get your weight in kilograms).
Step 2: Multiply your weight in kilograms by 0.9 if you are a woman or 1.0 if you are a man.
Step 3: Multiply by 24
Step 4: Multiply by your “Lean Factor” from the table below (read on to learn how to find your body fat percentage if you don’t know it)
Example using my stats: 61 kg (134.5 lbs.) x 0.9 (female) x 24 x 0.95 (20% body fat) = 1252
This number is called your Basal Metabolic Rate (BMR). It’s how many calories you would burn in a day if you just lay on the couch all day and did nothing.
To find out how many calories you actually burn in a day, you need to multiply with your “Activity Modifier” from the table below.
Step 5: Multiply by Activity Modifier
My daily calorie need would be: 1252 (my BMR) x 1.55 (Light Activity) = 1940 calories/day
Important: No matter what this formula says, never eat less than 1,200 calories per day on average without consulting your medical team first. A very low daily calorie intake can lead to a slower metabolism, hormonal problems, and a number of other medical issues.
How to find your body fat percentage
As you can see, calculating your daily calorie needs is actually pretty simple, as long as you know your body fat percentage. Most gyms should be able to measure that for you, or a trainer can give you a very good estimate just by looking.
You can also use a tape measure and this online calculator to estimate your body fat percentage. It’s not as accurate, but you really only need an approximate number, so it should be good enough.
If you want a more accurate number (and to track any changes), you can invest in a scale that measures body fat percentage (you can buy the one I use HERE). It’s only $27.99 so it’s a worthwhile investment if you want to track your weight and body fat percentage.
How to decide your activity factor
The main mistake people make when using this calculation is to overestimate their physical activity level.
Even though I live a very active lifestyle and work out almost every day, I still only use the “Light Activity” multiplier. And that may even be on the high side because I also spend a lot (too much) time in front of a computer.
The higher multipliers are for people who use their bodies almost constantly throughout the day and therefore need a lot of energy, like construction workers, pro athletes, etc.
If you are pretty fit and active, you should probably use the “Light” or “Very Light” multiplier. If you are just starting a fitness program, use the “Very Light” multiplier.
Now that you know how many calories you burn in a day, the next step is to decide if you want to lose or gain weight.
How many calories should you eat to lose weight?
If you are trying to lose weight, I recommend eating around 400-500 calories less than you burn daily. That calorie deficit should lead to a weight loss of about 1 pound per week, which is a very healthy and sustainable weight loss.
I know it can be tempting to lower your daily calorie intake more if you are trying to lose weight, but it’s not a good idea. When you lose weight quickly by restricting your calories, you also lose muscle mass, and the weight you lose is much more likely to come right back (as fat) as soon as you stop dieting.
Instead, add more physical activity to your daily routine. Even just 15-30 minutes of light to moderate exercise such as walking can burn calories, increase your metabolism, and help you reach your goal weight.
To learn more about healthy calorie deficits, read our guide Can Eating Too Little Make You Gain Weight?
How many calories should you eat to gain weight (muscle)?
If you want to gain muscle, start out at 500 calories/day more than your maintenance calories and see what happens. If you find that you are also putting on a little too much fat, decrease your calories slightly.
Just like weight loss, healthy weight gain should happen slowly. If you want to gain weight and add muscle mass without adding (much) fat, focus on eating a healthy diet, incorporate exercise (and especially resistance training) into your daily routine, and aim for a caloric intake that’s only slightly higher than your maintenance calories.
How accurate is this formula?
While this calorie calculator is quite accurate for most people, it is based on an “average” person and therefore isn’t perfect for everyone.
It doesn’t take differences in natural metabolism into account, so if you have a particularly high or low metabolism (for example because of thyroid disease), the result from this formula won’t be accurate.
Because your natural metabolism declines as you age, the formula also tends to underestimate how many calories teenagers need and overestimate the daily calorie requirements for people older than 60.
It’s also the most accurate for people who are close to the “average weight”. If the result of your calculation is that you need less than 1,400 daily calories or more than 2,500 daily calories to maintain your current weight, then it’s recommended that you talk to your doctor or dietitian before making any changes to your diet.
Frequently asked questions
There are roughly 3,500 calories in 1 pound of body fat. This means that, in principle, you will lose 1 pound per week with a calorie deficit of 500 calories/day (3,500 calories/week).
In reality, weight reduction is often a little slower than this as your body adjusts dynamically to any calorie reductions by lowering your metabolism.
It can be very hard to know how much you are actually eating without counting calories. Research shows that people eating in fast-food restaurants underestimate how many calories are in their meal by up to 500 calories.
You can use apps such as MyFitnessPal or Lifesum to track your daily calorie intake (and daily activity).
To ensure you reach your daily calorie targets, it’s also a good idea to follow a meal plan. You can either create your own or simply pick one from my meal plan library.
Munpreet Randhawa
Hello!
I am a type one diabetic and am browsing the site and this is great information and is helping me build a great food plan. However, I did have a question. I noticed that on this plan, there are carbs at every meal. I am trying to lose weight in a healthy way (which is why I am loving the information) and I was just curious as to why? I know for no/very low carb I can do Keto, but I want to ensure I am doing a life style change that will work for me. 🙂 Thank you!
Christel Oerum
I like to spread out the carbs throughout the day to balance out blood sugars. I’ve found that smaller meals with a reasonable (what’s reasonable depends on the individual) amounts of carbs are easier to manage and can help keep you full and fueled throughout the day
Dee
Decreasing your calories By 400-500 would put me at 1500 to lose that pound per week I eat more than this already and I am losing that pound.
Also to lose the 2lbs I would be at 1,000 calories per day which for women is dangerous.
Of to see what’s on the menu in the diet plan as I’m always looking for new things as I’m type 2 diabetic.
Christel Oerum
Hi Dee,
That’s a great observation. You should always include your starting point. This is just math but if you’re in tune with your current habits they should definitely be included in the equation. As a rule of thumb, I never recommend going below 1200 calories per day, I’d rather increase activity
Or
Hi!
I’m exploring the website and love all the info! I have a question about this daily calorie need. I am quite overweight and I want to lose weight, but according to this sum I should eat about 3400 cal a day! That can’t be right, can it? Do you recommend another way to find out how much I need?
Christel Oerum
You might need to track your food for a few days to figure out what your baseline is. It can be quite an eye-opening exercise. My favourite tool for tracking is MyFitnesPal. If you find that you’re consuming 3000 calories, I’d not suggest you go up in calories but rather “clean’ up the ones you’re eating and start with a 200-500 calorie reduction.
The calculators don’t know you, so you’re smart to not just go by what they say
Val
Love this! First time reader. I am a type 1 diabetic for almost 27 years. I have been doing a exercise boot camp for 9 months now and my sugar keeps dropping about 1/2 hour in to the boot camp. I haven’t really exercised that much in past years until recently(13+ years of not really exercising). The boot camp is 60 minutes long. 3 days a week. I also do indoor cycling 3 days for 45-60 minutes. And I do personal training 2 days a week for 60 minutes. And I take care of my special needs 12 year old son.
My sugar only drops only during boot camp. I don’t know what else to try. I have tried everything my doctor has suggested to try to keep my sugar up during boot camps. I have lost 34lbs since January and still have roughly 50more pounds to lose to get to healthy weight. And my insulin sensitivity has changed drastically. Food intake seems to be part of my struggle. I weigh roughly 206.
Dayna
Hi, It is me again. I did figure out how to change it in MFP. But in rechecking, my number was 2700 before deducting for weight loss. And if I go with the 30-40-30 percentages that leaves me with 168 grams of carbs. My endo wanted to to be under 100 g. I am just trying to understand this and maybe I am doing something wrong. Thanks again,
Christel Oerum
If your doctor has given you a recommendation I would suggest that’s what you go with. You can always ask your doctor how she/he has decided on your goals if in doubt
Dayna
Hello, I am a new reader and love your blog! I am a T1 diabetic on a pump trying to lose weight, for the first time I think it is actually possible. My endo wants me to log my diet in My Fitness Pal. It says my calories should be 1200 a day. I calculated using your method and it was 2200 before subtracting 500 for weight loss. I am confused. I dont think I can change the calories in My Fitness Pal, plus that is a big calorie difference. Thanks in advance.
Christel Oerum
Hi Dayna – You can change the calories and macro goals in MFP. It’s easier if you do it from your computer though.
Since I don’t know you or your activity level it’s impossible for me to tell you the right calorie level. I can tell you that as a rule of thumb 1200 is the ABSOLUTE minimum that I would ever recommend. Unless your doctor gave you that direction I would start a little higher. You can always reduce calorie later if needed. Please remember that the calorie calculators are based on averages, you’re not average, so it can give you a starting point but should not be considered final truth
Tricia
Quick question regarding calorie count. Fitness apps such MyFitnessPal increase your overall caloric and macro nutrient needs/goals through the day when exercise is entered into their equation. Considering this post and contrary to these apps, should a calculated 1450 kcal/day value remain the same [and not increase] regardless of bouts of physical activity?
Christel Oerum
Calories burned (including exercise) is included in the formula already.
In general, I recommend that you don’t rely too much on your fitness trackers calories burned. I like my fitness tracker but also know that it’s highly inaccurate. It’s a great reminder to get your steps in, and very useful if you do HR training but I would count on it for more than that.
Melissa
How do I get my body fat percentage?
Christel Oerum
Your local gym should be able to help you. You can also buy some fairly accurate measuring equipment on Amazon.
Will
Hi, what if I’m already at a pretty good body fat percentage and I just want to try and lose a little body fat, not lose weight. I also don’t want to lose muscle so would I still drop the calories 4-500?
Tobias Oerum
Hi Will,
I would recommend that you aim for a 200 calorie deficit and add more cardio to your workout routine (if you aren’t doing a lot already). Then re-evaluate after 2 weeks when you see what results you have been getting. If you just want to lose a little weight and aren’t in a hurry, starting with a small calorie deficit is generally a good idea. You can always increase it later if you have to.
Kelley Chaffee
I’m a new reader and loving your blog!!
How do work outs factor in to this equation? The “activity” level doesn’t count for actual work outs right? For example I run approx 50 miles a week and do 3 weight tough lifting sessions a week. Without workouts I burn about 1,500 a day. How would I figure out what my real needs may be after workouts are figured in if I want to lose 5-7 lbs? Thanks!
Tobias Oerum
Hi Kellye,
Thank you so much! Love new readers 🙂
The activity level does account for workouts. I recommend using the “light” or even “very light” activity multiplier, even though you work out a lot. The higher multipliers are mostly for people who are constantly active throughout the day.
If your BMR is 1,500, your daily maintenance calories are approx. 2,325 (1,500 x 1.55). Since you are trying to lose weight, I would suggest you eat 500 calories/day less than that, so about 1,800 calories/day. That should give you a moderate and sustainable weight loss.
If you are in a hurry, you can go down to 1,600 calories/day but I wouldn’t go lower than that.
-Tobias