About the Calorie Calculator
This free calorie calculator helps people in the United States get a quick, private estimate before they talk to a lender, insurer, employer or advisor. There is no signup, nothing is stored on our servers and every result updates instantly in your browser.
How this calculator works
The calculator uses the Mifflin-St Jeor equation to estimate basal metabolic rate, then multiplies by an activity factor to estimate maintenance calories.
Worked example
A 30-year-old, 165 lb, 68 in male with moderate activity needs about 2,600 kcal per day to maintain weight. Change any input above to see how the result moves, which is the fastest way to understand which factor matters most for you.
Tips to get a better result
Estimates vary by up to 10 percent. Track your weight over a few weeks and adjust. Do not use extreme deficits without medical guidance.
Key factors that change your result
This uses the Mifflin-St Jeor equation for basal metabolic rate, multiplied by an activity factor. Real needs vary with muscle mass, genetics and daily movement. Adjust gradually and consult a professional before major diet changes.
Accuracy and limits
Every calculator on 100tools uses standard published formulas combined with average US market assumptions. Real results depend on your personal circumstances, so treat the output as a starting point and confirm with a qualified professional. Read more on our methodology page.
Frequently asked questions
What is BMR?
Calories your body burns at rest.
Is this medical advice?
No. See a doctor or registered dietitian for personal guidance.
Is the calorie calculator free to use?
Yes. Every calculator on 100tools is free with no registration.
Do you store the numbers I enter?
No. Calculations run in your browser and nothing you type is sent to our servers.