This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Results include calorie targets for weight loss, maintenance, and muscle gain. All calculations are performed locally in your browser for complete privacy.
Figuring out how many calories you need to eat just to stay the same weight—without gaining or losing—can feel like guesswork. You might have tried tracking everything for a week, only to end up confused. Or maybe you’ve searched for “how to calculate my daily calorie needs” and landed on confusing formulas that make your eyes glaze over. The good news? You don’t need to be a nutritionist or a math whiz. A maintenance calorie calculator does the heavy lifting in seconds, and the one we built at heycalc.org gives you a clear, personalized number—plus actionable targets for losing or gaining weight.
Unlike many online tools that ask you to upload sensitive health data to a server, this calculator works entirely in your browser. Everything you enter—your age, weight, height, and activity level—stays on your device. That means no privacy worries and no waiting for a page to reload. In this guide, I’ll show you exactly how to use it, why the Mifflin-St Jeor equation is your best bet for accuracy, and how to turn your results into a real eating plan.
Here’s a common mistake: assuming your “metabolism” is either fast or slow and leaving it at that. In reality, your body burns a baseline number of calories just to keep your heart beating, your lungs breathing, and your cells regenerating. That’s your Basal Metabolic Rate (BMR). On top of that, everything you do—walking to the kitchen, typing an email, going for a run—adds more burned calories. Your Total Daily Energy Expenditure (TDEE) is the sum of both. And that’s your true maintenance number.
The problem? Most people either:
A solid TDEE calculator removes the guesswork by using a scientifically validated formula. The Mifflin-St Jeor equation, which this tool uses, has been shown to be more accurate than older formulas like Harris-Benedict, especially for people with average body compositions. It takes your gender, age, height, and weight, then adjusts for your specific activity level.
You don’t need to download an app or sign up for a newsletter. Here’s exactly how it works, whether you’re on a phone during a quick break or at your desk planning a new fitness routine.
When you click that button, everything is processed right there on your laptop or phone. There’s no data upload, no server queue, and absolutely no chance of your information being stored somewhere. For anyone who has ever worried “is it safe to use an online calorie calculator with my real stats?”—this is your answer.
After you hit calculate, you’ll see two big numbers: your BMR and your TDEE. The BMR number is what your body burns if you stayed in bed all day. You don’t eat below that—it’s your energy floor. The TDEE number is your true maintenance calorie level. Eat this many calories each day, and your weight should stay stable.
Below those numbers, a table shows five different calorie targets:
Let’s say your TDEE comes out to 2,450 calories. To lose weight at a steady pace, you’d aim for about 1,950 calories per day. To build muscle, you’d bump up to 2,700. The calculator gives you both numbers so you don’t have to do any extra math.
This is a fair question. You’ve probably seen a dozen online calorie calculators that all give slightly different numbers. Here’s why this one stands out.
First, the Mifflin-St Jeor equation is widely cited in sports medicine and nutrition research. It was developed specifically to be more accurate for modern populations. Second, the tool lets you adjust your activity level in fine detail—not just “active” or “not active.” Third, all calculations are local, so there’s no variation caused by server lag or data compression.
That said, no calculator is perfect. Your actual maintenance calories can vary based on factors like muscle mass, sleep quality, and even outside temperature. Use this number as your starting point. Eat at that level for two weeks and track your weight. If you’re slowly gaining, reduce by 100 calories. If you’re losing, add 100 back. The calculator gives you a scientifically sound anchor—then you fine-tune based on real life.
I want to touch on this one more time because it’s that important. Many free maintenance calorie calculator tools online look simple, but they send your height, weight, age, and gender to a remote server. That might not seem like a big deal until you realize that health data is uniquely personal. Some sites even sell that information to advertisers or use it to build profiles on you.
The calculator on heycalc.org works differently. Open it, enter your stats, and hit calculate. Open your browser’s developer tools (if you’re technical) and watch the network tab—you’ll see zero data being transmitted. Every calculation happens using JavaScript right inside your local browser. When you close the tab, everything disappears. There’s no account to delete, no settings to clear, and no hidden tracking.
This makes it ideal for anyone who’s ever asked “do I have to sign up for a calorie calculator?” or “is there a private way to calculate my TDEE without creating an account?” The answer is yes, and this is it.
You have your maintenance number, your deficit targets, and your surplus goals. The hardest part—the math—is done. Now it’s about action. If you want to lose weight, start tracking your food for three days just to see where you’re at. If you want to build muscle, add 250 calories of mostly protein and complex carbs to your daily meals.
And remember: the best tool is the one you actually use. Bookmark this maintenance calorie calculator or save the link. Come back anytime your weight, activity level, or goals change. Because it works entirely in your browser, you can use it daily, weekly, or monthly—with complete privacy, zero signups, and no surprises.
Go ahead. Calculate your numbers. Then take one small step tonight. You’ve got this.
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Results include calorie targets for weight loss, maintenance, and muscle gain. All calculations are performed locally in your browser for complete privacy.
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Results include calorie targets for weight loss, maintenance, and muscle gain. All calculations are performed locally in your browser for complete privacy.
Review the result before downloading or using it in another application, especially when the input contains important data.
Your maintenance calorie level is exactly your TDEE (Total Daily Energy Expenditure). To find it, use the calculator above with your accurate age, weight, height, gender, and activity level. For example, a moderately active 30-year-old woman who is 165 cm tall and weighs 65 kg typically needs around 2,100–2,300 calories per day to maintain her weight. But your personal number may be different—that’s why running your own numbers is essential.
Yes, for most people. Multiple studies have found that Mifflin-St Jeor estimates BMR within 10% of measured values for over 95% of individuals. Harris-Benedict was developed in 1919 and tends to overestimate calories by about 5-10%, especially in younger and more active people. That’s why this calculator uses Mifflin-St Jeor exclusively.
Absolutely. The tool works in any modern mobile browser—Chrome, Safari, Firefox, or Edge. There’s no app to download, no storage space taken up, and no permissions to accept. Just open the page, and it looks and works like a native mobile tool. All buttons are sized for thumbs, and the results table scrolls smoothly on small screens.
The calculator provides a 500-calorie deficit because that’s what most experts consider safe and sustainable for long-term fat loss. Larger deficits (like 750 or 1,000 calories) can lead to muscle loss, fatigue, and nutritional deficiencies. If you’re under medical supervision, you can certainly go lower, but for most people, sticking to a 500-calorie deficit from their maintenance calorie needs is the healthiest approach.