Calorie Calculator: How Many Calories Should You Eat Per Day?
A calorie calculator tells you the number. The hard part is what comes after: what does a day at 1,800 or 2,400 calories actually look like — and how do you know your real meals hit it? This page does all three. Plug in your numbers below for a Mifflin-St Jeor estimate of your maintenance and goal calories, get a sample day built around your target, then use the scanner to check your own meals against it.
⚠️ Why This Matters for Your Health
- • Eating too few calories = slow metabolism, muscle loss, fatigue
- • Eating too many calories = weight gain, insulin resistance, health risks
- • Wrong calorie target = stalled progress, wasted effort, frustration
Calculate your exact needs now to avoid these problems.
👥 Who Should Use This Calorie Calculator?
- ✓ People trying to lose weight
- ✓ Athletes and gym-goers
- ✓ Keto, vegan, or paleo dieters
- ✓ Seniors managing health
- ✓ Busy professionals confused by nutrition
- ✓ Parents planning family meals
How many calories should I eat per day?
Direct answer: Most adults can estimate daily calorie needs with the Mifflin-St Jeor equation: for weight loss, eat roughly 500 calories below maintenance; for muscle gain, roughly 250 above. Sedentary maintenance often lands near 1,800–2,500 calories/day depending on age, weight, height, and activity. Calculate yours above, then scan your meals free at foodidentifier.com to compare.
Expansion: Mifflin-St Jeor estimates your basal metabolic rate (BMR) — what your body burns at rest — then multiplies by an activity factor: sedentary, light, moderate, very active. The result is your maintenance calories, the level where your weight stays roughly stable. Weight loss targets are typically maintenance minus 500/day (about a pound a week); weight gain is plus 250–500. These are estimates, not prescriptions — metabolism varies, and the equation runs on averages. Recalculate every 4–6 weeks as your weight changes, and treat the result as a starting target you adjust based on real results, not a number carved in stone.
Why the scanner completes the picture: knowing your target is step one; eating to it is step two. FoodIdentifier turns your phone camera into a calorie counter — photograph any meal and get its calories in seconds, then add them up against your daily target. No typed logging, no database hunting.
Scan it free at foodidentifier.com — no app, no sign-up.
Your number → a sample day → your meals
Your calculator result includes a sample day of scan-ready meals built to your calorie target — breakfast, lunch, dinner, and a snack, each with estimated calories and protein. Think of it as a template, not a meal plan prescription: swap foods freely, then scan your own versions to check they still fit.
What the scanner adds that a calculator can't
A calculator assumes you know what's in your food. Most people don't — restaurant portions, cooking oils, and "healthy" snacks are where estimates quietly break. The scan closes that gap: photo the plate, get the calories, compare to your target in seconds.
Frequently Asked Questions
Is this calorie calculator free?
Yes — and so is the scanner behind it. FoodIdentifier is free at foodidentifier.com: no app, no account, no card.
How accurate is the Mifflin-St Jeor equation?
It's the most widely validated resting-metabolic-rate formula in clinical practice, accurate within about 10% for most people — but it's still an estimate. Use real weigh-ins over 2–3 weeks to fine-tune.
Should I eat back exercise calories?
For weight loss, generally no — most people overestimate burn. If you train hard, use the calculator's activity setting instead of adding back workout calories.
How often should I recalculate?
Every 4–6 weeks, or after gaining/losing more than ~5 lbs. Your maintenance number moves with your weight.
What's the minimum safe calorie level?
Very low intakes can cause nutrient gaps and muscle loss. If your result looks low, talk to a clinician before dieting aggressively — this is not medical advice.
How do I track calories without typing everything in?
Photograph your meals with FoodIdentifier's free scanner — calories and macros in seconds, right against your calculator target.
Do I need an app to use the scanner?
No. FoodIdentifier runs in your browser on iPhone, Android, desktop, or tablet.
Why This Is More Than a Calculator
Most calorie calculators stop at a number.
Food Identifier explains why your number works, how to hit it with real foods, and what to change if progress slows.
How This Calorie Calculator Works
This calculator uses three well-established BMR equations and multiplies by an activity factor to estimate your total daily calorie needs. Of the three, the Mifflin-St Jeor Equation is considered the most accurate for most people. The Katch-McArdle Formula can be more accurate if you know your body fat percentage.
Mifflin-St Jeor Equation
Men: BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161
Revised Harris-Benedict Equation
Men: BMR = 13.397W + 4.799H − 5.677A + 88.362
Women: BMR = 9.247W + 3.098H − 4.330A + 447.593
Katch-McArdle Formula (best if you know body fat %)
BMR = 370 + 21.6 × (1 − F) × W
W = body weight in kg, H = height in cm, A = age, F = body fat fraction
Your BMR is then multiplied by an activity factor (1.2–1.95) to estimate total daily energy expenditure (TDEE). To lose 1 lb/week, subtract ~500 calories/day from your TDEE. 1 pound ≈ 3,500 calories.
Calorie Counting for Weight Loss: Step-by-Step
- 1
Determine Your BMR
Use the calculator above. If you know your body fat %, the Katch-McArdle Formula gives the most accurate estimate.
- 2
Set Your Weight Loss Goal
1 lb ≈ 3,500 calories. A 500 cal/day deficit = ~1 lb/week loss. Do not exceed a 1,000 cal/day deficit (2 lbs/week max).
- 3
Track Your Calories
Use an app, a food scanner, or a journal. Scan food photos for instant calorie counts.
- 4
Monitor Progress Weekly
Weigh yourself at the same time each day. Track trends over weeks, not days — weight fluctuates daily from water.
- 5
Adjust as Needed
Recalculate every 4–6 weeks or after 5+ lbs of change. Your calorie needs shift as your weight changes.
Zigzag Calorie Cycling
Zigzag calorie cycling alternates high and low calorie days to prevent the body from adapting to a lower calorie intake — which can stall weight loss. Both approaches meet the same weekly calorie target.
Schedule 1 (2 High + 5 Low)
High days: ~2,300 cal (×2)
Low days: ~1,775 cal (×5)
Total: ~14,000 cal/week
Schedule 2 (Gradual)
Calories increase and decrease gradually across the week
Total: ~14,000 cal/week
High and low days should differ by ~200–300 calories. High-calorie days are often set at your maintenance TDEE.
Sample Meal Plans: 1200, 1500 & 2000 Calories
| Meal | 1,200 Cal Plan | 1,500 Cal Plan | 2,000 Cal Plan |
|---|---|---|---|
| Breakfast | All-bran cereal (125) Milk (50) Banana (90) | Granola (120) Greek yogurt (120) Blueberries (40) | Buttered toast (150) Egg (80) Banana (90) Almonds (170) |
| Snack | Cucumber (30) Avocado dip (50) | Orange (70) Greek yogurt (120) Blueberries (40) | |
| ⟶ Total | 345 cal | 390 cal | 490 cal |
| Lunch | Grilled cheese + tomato (300) Salad (50) | Chicken & veg soup (300) Bread (100) | Grilled chicken (225) Grilled vegetables (125) Pasta (185) |
| Snack | Walnuts (100) Apple (75) | Peanut butter (75) Hummus (50) Baby carrots (35) | Crackers (65) |
| ⟶ Total | 525 cal | 560 cal | 600 cal |
| Dinner | Grilled Chicken (200) Brussels sprouts (100) Quinoa (105) | Steak (375) Mashed potatoes (150) Asparagus (75) | Grilled salmon (225) Brown rice (175) Green beans (100) Walnuts (165) |
| ⟶ Total | 405 cal | 600 cal | 665 cal |
Values are approximate. Use our AI food scanner for precise tracking.
Calories in Common Foods
| Food | Serving | Calories | kJ |
|---|---|---|---|
| Apple (Fruit) | 1 (4 oz.) | 59 | 247 |
| Banana (Fruit) | 1 (6 oz.) | 151 | 632 |
| Grapes (Fruit) | 1 cup | 100 | 419 |
| Orange (Fruit) | 1 (4 oz.) | 53 | 222 |
| Pear (Fruit) | 1 (5 oz.) | 82 | 343 |
| Peach (Fruit) | 1 (6 oz.) | 67 | 281 |
| Strawberry (Fruit) | 1 cup | 53 | 222 |
| Watermelon (Fruit) | 1 cup | 50 | 209 |
| Asparagus (Vegetables) | 1 cup | 27 | 113 |
| Broccoli (Vegetables) | 1 cup | 45 | 188 |
| Carrots (Vegetables) | 1 cup | 50 | 209 |
| Cucumber (Vegetables) | 4 oz. | 17 | 71 |
| Lettuce (Vegetables) | 1 cup | 5 | 21 |
| Tomato (Vegetables) | 1 cup | 22 | 92 |
1 cup ≈ 250 ml. For precise values, scan your food with AI.
Calories Burned from Common Exercises (per hour)
| Activity | 125 lb | 155 lb | 185 lb |
|---|---|---|---|
| Golf (using cart) | 198 | 246 | 294 |
| Walking (3.5 mph) | 215 | 267 | 319 |
| Kayaking | 283 | 352 | 420 |
| Softball / Baseball | 289 | 359 | 428 |
| Swimming (moderate) | 397 | 492 | 587 |
| Tennis (general) | 397 | 492 | 587 |
| Basketball (general) | 340 | 422 | 503 |
| Soccer (general) | 397 | 492 | 587 |
| Bicycling (12–14 mph) | 454 | 562 | 671 |
| Football (general) | 399 | 494 | 588 |
| Running (9 min mile) | 624 | 773 | 923 |
Source: Harvard Health Publications. Values are estimates for 1 hour of activity.
Energy from Common Food Components
| Component | kJ/g | kcal/g | kJ/oz | kcal/oz |
|---|---|---|---|---|
| Fat | 37 | 8.8 | 1049 | 249 |
| Protein | 17 | 4.1 | 482 | 116 |
| Carbohydrates | 17 | 4.1 | 482 | 116 |
| Fiber | 8 | 1.9 | 227 | 54 |
| Alcohol (ethanol) | 29 | 6.9 | 822 | 196 |
| Organic acids | 13 | 3.1 | 369 | 88 |
| Sugar alcohols (polyols) | 10 | 2.4 | 283 | 68 |
Frequently Asked Questions
Track Calories Without Guessing
Scan any food photo and get instant, accurate calorie counts. No manual logging. No guessing.
How This Calorie Calculator Works
The calculator takes four inputs and runs them through a two-step formula:
- Age, sex, weight, height feed the Mifflin-St Jeor equation to estimate BMR.
- Activity level applies a multiplier (1.2 to 1.9) to BMR, producing TDEE.
- Goal adjusts TDEE up or down by a fixed amount (−500 for loss, +500 for gain).
We use Mifflin-St Jeor as the default because a 2005 American Dietetic Association review found it to be the most accurate BMR prediction equation for the general population. If you know your body fat percentage, the Katch-McArdle formula can be more accurate because it uses lean mass instead of total body weight.
The 3 Calorie Formulas Compared
All three estimate BMR. The difference between them is usually 50 to 150 calories, which matters more at extreme body sizes than for most people.
| Formula | Equation | Best For | Notes |
|---|---|---|---|
| Mifflin-St Jeor | 10W + 6.25H − 5A + S | Most people; default choice | S = +5 (men), −161 (women) |
| Harris-Benedict (revised) | 13.397W + 4.799H − 5.677A + 88.362 | Legacy reference; slightly higher | Men formula shown; different for women |
| Katch-McArdle | 370 + 21.6 × LBM | If you know body fat % | LBM = lean body mass in kg |
W = weight in kg, H = height in cm, A = age in years, S = sex constant, LBM = lean body mass.
Worked Example: 30-Year-Old Female, 65 kg, 165 cm, Lightly Active, Weight Loss
Here is the full manual calculation from body stats to daily calorie target.
Step 1 — BMR (Mifflin-St Jeor, women):
BMR = 10 × 65 + 6.25 × 165 − 5 × 30 − 161
BMR = 650 + 1031.25 − 150 − 161 = 1370 kcal
Step 2 — TDEE (lightly active × 1.375):
TDEE = 1370 × 1.375 = 1884 kcal
Step 3 — Goal calories (weight loss −500):
Target = 1884 − 500 = 1384 kcal/day
Source: Mifflin-St Jeor (1990); activity multipliers from Harris-Benedict convention.
Calories for Your Goal: Maintain, Lose, and Gain Targets
Once you know your TDEE, the adjustment is simple arithmetic. One pound of body weight is approximately 3500 calories.
| Goal | Adjustment | Expected Rate | Notes |
|---|---|---|---|
| Lose weight | −500 kcal from TDEE | ~1 lb/week | Do not exceed −1000 kcal/day |
| Maintain | 0 kcal (eat TDEE) | Stable weight | Recalculate every 4–6 weeks |
| Gain muscle | +300 to +500 kcal above TDEE | ~0.5–1 lb/week | Pair with strength training |
Activity multipliers: 1.2 (sedentary), 1.375 (lightly active), 1.55 (moderately active), 1.725 (very active), 1.9 (extra active).
What Affects Your Calorie Needs
Your TDEE is not a fixed number. It shifts with several factors:
- Age: BMR drops about 1 to 2 percent per decade after 20, largely from muscle loss.
- Sex: Men typically have higher BMR than women of the same size due to more lean mass.
- Muscle mass: Each kilogram of muscle burns more calories at rest than fat. Building muscle raises BMR.
- Activity level: The biggest variable. Going from sedentary to moderately active can add 400 to 600 calories to TDEE.
- NEAT: Non-exercise activity thermogenesis (fidgeting, walking, standing) can vary by 200 to 900 calories per day between people.
This is why two people of the same weight can have very different calorie needs, and why your own needs change over time even if the scale does not move.
How to Track Calories Accurately
A calorie target only works if you can track what you actually eat. Here is an honest, practical approach:
- Use a food scale for the first two weeks. Most people underestimate portions by 20 to 40 percent.
- Log everything, including cooking oil, sauces, and drinks. These add up fast.
- Scan meals with FoodIdentifier's photo scanner to estimate calories without manual lookup, especially for home-cooked food.
- Check your daily total at dinner and adjust the last meal to close any gap.
- Review weekly trends, not daily numbers. Weight fluctuates 1 to 3 pounds daily from water alone.
- Recalculate your target every 4 to 6 weeks or after a 5 pound change.
The photo-scan approach removes the biggest barrier to tracking: the friction of weighing and searching every food. Scan your plate, see the calories, and let the daily total build itself.
Safe Minimum Calorie Intakes
Dropping calories too low is not faster, it is counterproductive. Chronic undereating slows metabolism, causes muscle loss, and leads to nutrient deficiencies.
Women: Do not eat below 1,200 calories per day without medical supervision.
Men: Do not eat below 1,500 calories per day without medical supervision.
Source: Harvard Health Publishing. These are floor levels for short-term diets. Most adults need more than the minimum to train, recover, and function well.
Calorie Calculator FAQs
Disclaimer: This calorie calculator provides estimates for educational purposes only and is not medical advice. Individual needs vary based on health status, activity, and goals. Consult a registered dietitian or physician before starting any significant dietary change.
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