How Many Calories a Day? Calculate Your Needs (TDEE)

In short

Yes. Weight, age, activity level and other factors shift, so your estimated need moves too. Reassess every now and then.

Radish · 7 min

"How many calories a day?" is probably the first question people ask when they start paying attention to what they eat. The truth is there's no universal number: your needs depend on your body, your activity level, your age and your current goal.

Good news: with two simple ideas, BMR and TDEE, you can get a useful estimate in a few minutes. It's not an exact science, but a reference point that helps you decide calmly. Let's see how it works, step by step, without dense formulas or unrealistic promises.

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BMR and TDEE: the basics

Two terms to remember:

BMR (basal metabolic rate): the energy your body spends at complete rest, just to stay alive (breathing, keeping warm, the heart beating).
TDEE (total daily energy expenditure): your BMR multiplied by your activity level. It's the estimate of your real daily needs.

In other words: BMR is the foundation, TDEE is the total once daily life is added.

Estimate your BMR, then your TDEE

BMR is often calculated with the Mifflin-St Jeor equation, which uses weight, height, age and sex. You don't need to memorise it: most tools do it for you.

Then you apply an activity factor to your BMR to get your TDEE:

Sedentary (little or no exercise): about x1.2
Lightly active (1-3 sessions/week): about x1.375
Moderately active (3-5 sessions): about x1.55
Very active (6-7 sessions): about x1.725

These multipliers are still approximations: your real TDEE can vary, and that's normal.

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Deficit or surplus: stay reasonable

Once you've estimated your TDEE, you can adjust toward your goal, carefully:

Eat around your TDEE to stay steady.
A moderate deficit (often in the range of 10 to 20 percent below TDEE) to gently lower intake.
A slight surplus above TDEE if the goal is to increase intake.

Avoid extremes: eating far too little is rarely sustainable and can backfire. The idea is to find a pace you can keep, not a sprint. Depending on which way you go, two guides cover it in detail: weight loss and bulking up.

General information, not medical advice. If in doubt or with specific needs, talk to a healthcare professional.

Common mistakes to avoid

A few classic pitfalls often skew both the estimate and the tracking:

Overestimating your activity. Many people rate themselves "very active" when most of the day is sedentary. When in doubt, pick the lower factor.
Forgetting liquid extras. Sugary drinks, juices, fancy coffees: they add up fast without you noticing.
Aiming for too aggressive a deficit. Slashing intake is rarely sustainable and can hurt your energy and mood.
Judging over a few days. The body fluctuates (water, digestion). Think in terms of two to four weeks.

Avoiding these traps makes your target number far more useful.

Track your intake without the hassle

Working out how many calories per day you need takes five minutes; holding the count for a month is the hard part. A target number is only useful if you can track it easily. That's where a simple counter helps: log your meals, see where you stand during the day, adjust. Radish does it all counting without a connection, with no account and no ads: your diary stays on your phone — never sent to our servers (except AI or barcode scanning, if you use them), never sold — exceptions: barcode scanning and the optional AI, which you trigger yourself, and anonymised usage statistics sent to Google (in the EU, only if you agree). And with the Nutri-Score shown when the data allows, you track both quantity and quality. Depending on your goal, our seven ways to track what you eat page points to the matching guide.

FAQ

Does my TDEE change over time?

Yes. Weight, age, activity level and other factors shift, so your estimated need moves too. Reassess every now and then.

Do I need to hit the exact number every day?

No. It's an indicative average. Intake naturally varies day to day; what matters is the trend over time.

Is TDEE accurate to the calorie?

No, it's an estimate. The formulas give a useful ballpark, not an exact measurement.

Knowing your calorie needs isn't about obeying a number, it's about giving yourself a reference point to make informed choices. Calculate your TDEE, adjust reasonably, and watch over several weeks. To track it all simply and privately, try Radish, free: counting without a connection, no account, with the Nutri-Score at hand.

General information, not medical advice.

🔎 Methodology & sources. Every nutrition figure in this article is cross-checked against official sources (ANSES, EFSA, WHO, CIQUAL/USDA, French Public Health agency), and health topics are reviewed before publication against our internal reference framework. See our full methodology →