Calorie Calculator
Calculate your daily calorie needs: BMR and TDEE from the Mifflin-St Jeor equation, plus weight loss and gain targets - free and 100% private.
Enter your details to see your daily calorie needs.
Features
100% Browser-Based
Your age, weight, and body data never leave your device. All math happens locally in your browser.
Free & No Sign Up
No registration, no email, no limits. Open the tool and get your numbers.
Instant Results
BMR, TDEE, and calorie targets update in real time as you adjust any input.
Mifflin-St Jeor Equation
Uses the formula dietitians consider the most accurate for estimating resting metabolic rate in healthy adults.
Goal Targets Included
See daily calories for mild loss, weight loss, maintenance, mild gain, and weight gain - with expected weekly change for each.
How to Calculate Your Daily Calories?
- Pick Metric (cm, kg) or US (ft, in, lb) units and your biological sex.
- Enter your age, height, and weight - results update live.
- Choose the activity level that matches your typical week.
- Read your BMR, maintenance calories (TDEE), and the target table for weight loss or gain.
Common Use Cases
Weight Loss Planning
Find the daily intake for a sustainable 0.25-0.5 kg per week deficit instead of guessing.
Muscle Gain
Get a lean-bulk calorie target with a modest surplus instead of an all-out bulk.
Maintenance Mode
After reaching your goal weight, use your TDEE to hold steady without rebounding.
Meal Planning
Translate a daily calorie budget into meals, snacks, and portion decisions.
Tips for Using Your Calorie Targets
- ✓ Weigh and measure yourself in the morning for consistent inputs - daily water shifts can mask real changes.
- ✓ Re-calculate after every 2-3 kg (5 lb) of weight change: your TDEE moves as you do.
- ✓ Track actual results for 2-3 weeks before adjusting; equation estimates carry about a ±10% margin of error.
- ✓ Protein and resistance training protect muscle in a deficit - a calorie target alone says nothing about what to eat.
Frequently Asked Questions
Is my data sent to any server?
No. The calorie calculator runs completely in your browser - your age, sex, height, weight, and results are never transmitted or stored anywhere outside your device. Body data combined with age is exactly the kind of information advertisers and data brokers pay for, which is why ToolsMio never sends it off your device in the first place. You can confirm this by opening the DevTools Network tab while using the tool: no requests carry your inputs. Even your entered values persist only in your own browser's local storage, purely so the form is still filled the next time you return.
How does the calorie calculator work?
It uses the Mifflin-St Jeor equation, introduced in 1990 and now considered more accurate than the older Harris-Benedict formula for healthy adults. First it computes your basal metabolic rate (BMR) - the energy your body burns at complete rest - from your sex, weight, height, and age. Then it multiplies BMR by an activity factor (from 1.2 for a desk-bound day to 1.9 for intense physical work or twice-daily training) to estimate your total daily energy expenditure, or TDEE. That TDEE is your maintenance intake: eat roughly that much and your weight stays put. The tool also shows ±250 and ±500 kcal targets, the conventional gentle and standard paces for weight change.
How many calories should I eat to lose weight?
A deficit of about 500 kcal per day below your TDEE produces roughly 0.45 kg (1 lb) of loss per week, which is the pace most health bodies recommend; the milder 250 kcal deficit halves that rate and is easier to sustain. The key word is 'roughly': metabolism adapts, water shifts, and no equation captures your exact burn - treat the output as a starting estimate, follow it for two to three weeks, and adjust based on what your scale and measurements actually do. Women should generally not go below about 1,200 kcal per day and men below about 1,500 without medical supervision, because very low intakes make it hard to get enough protein, vitamins, and minerals.
Why does my BMR drop as I get older?
Muscle is metabolically expensive tissue, and muscle mass naturally declines with age - roughly 3-8% per decade after 30 in inactive people. The Mifflin-St Jeor equation captures this with its age term: for a man, BMR decreases by 5 kcal for every year of age; for a woman, by 5 kcal plus the baseline difference. This is also why resistance training is the standard advice for protecting metabolism as you age: keeping muscle keeps your resting burn higher. Note that the equation estimates a typical person's BMR with a margin of error around ±10%, so two people with identical inputs can genuinely differ.
Which activity level should I choose?
Be honest and count only deliberate exercise, not your job title, unless your work is physically demanding. Sedentary (×1.2) means little or no exercise; Light (×1.375) means 1-3 workouts a week; Moderate (×1.55) means 3-5; Very active (×1.725) means 6-7; and Extra active (×1.9) covers hard physical labor plus training or twice-daily athletes. When in doubt, pick the lower level: people systematically overestimate activity and calorie burn, and an inflated TDEE quietly sabotages a weight-loss plan. You can also compute both levels and treat the pair as your uncertainty band.