How Many Calories Should I Eat a Day?

Cal360 Guides · Updated July 2026

There is no universal answer, and that's the point. A 5'4" woman who squeezes in two workouts a week and a 6'2" man training six days need wildly different numbers. Here's what actually determines your daily calories, and how to get a target built for your body instead of a number borrowed from a magazine headline.

Everything you burn in a day (your TDEE, or total daily energy expenditure) has four parts: your resting energy (the same number Apple Health shows, what your body uses just staying alive), movement (walking, chores, errands, the school run), digestion (the cost of processing what you eat), and workouts. Here's how a typical day splits up:

What determines your calorie needs

• Body size: height and current weight set your baseline burn (larger bodies burn more).
• Age: metabolism slows gradually over the decades.
• Sex: body composition differences shift the baseline.
• Activity: how often you work out, whether 0 to 2, 3 to 5, or 6+ times a week, plus daily steps.
• Your goal and pace: lose, maintain, or gain, and how fast you want to get there.

Combine those and you get your maintenance calories, which is what you burn per day. To lose weight, you eat below it (a 500/day deficit is about 1 lb/week). To gain muscle, you eat modestly above it with plenty of protein.

Why generic numbers backfire

"Eat 1,200 calories" is too aggressive for most people. Hunger wins, the diet breaks, and the rebound erases progress. "Eat 2,000" may be a surplus for a smaller, less active person. Both fail the same way: they weren't calculated for you. A sustainable target is one your actual body can run on while still losing at your chosen pace.

How Cal360 calculates your number

Cal360's 2-minute onboarding asks for your gender, height, weight, birthday, workout frequency, goal (lose, maintain, or gain), goal weight, and pace: nice and easy, steady progress, or faster results. It then produces your complete Daily Personalized Plan:

• Calories per day: e.g. 1,920 cals
• Protein: e.g. 120g (the macro that protects muscle while you lose fat)
• Carbs: e.g. 216g
• Fat: e.g. 64g

Every value is editable, and your dashboard tracks all four live as you log. Want the exact math? We publish the full methodology, formulas, and peer-reviewed sources behind every plan.

Your number isn't static

Two things should move your daily target, and Cal360 handles both:

• Exercise: with Apple Health sync, calories burned can be added back to today's goal, so a run earns you +100 cals and hard training days don't leave you under-fueled.
• Yesterday's leftovers: calorie rollover lets unused calories count toward the next day, which makes weekends and social dinners survivable.

Then make the number easy to hit

Knowing your target is step one; staying inside it daily is what moves the scale. Cal360 makes that part fast: photo scanning, voice logging, barcode scanning, and database search all log full calories and macros in seconds, and meal plans tell you what to cook to land on target.