ForgeScore™ BMR & TDEE Calculator
Estimate your basal metabolic rate, daily calorie expenditure, goal-based calorie intake, protein targets, and a realistic timeline for weight loss or muscle gain.
Basal Metabolic Rate
1,850
Total Daily Energy Expenditure
2,868
Suggested Calorie Targets
What Is BMR and TDEE?
Every calorie or protein target starts with two numbers: how much energy your body burns at rest, and how much it burns across a full day. Here's what each one actually measures.
Basal Metabolic Rate
The calories your body needs just to stay alive — breathing, circulation, cell repair, brain function — if you did nothing but rest for 24 hours. It's the floor, not a target to eat at.
Total Daily Energy Expenditure
Your BMR plus everything else: workouts, walking, fidgeting, digesting food. This is the number that actually reflects how many calories you burn in a normal day.
What Your Calories, Protein, and Timeline Actually Mean
BMR and TDEE are the inputs. These three numbers are what you actually act on.
Goal-Based Calories
Your TDEE adjusted for your goal — a moderate deficit for fat loss, a small surplus for muscle gain, or TDEE itself to maintain. The adjustment is intentionally conservative; aggressive deficits speed up muscle loss and rebound, not just fat loss.
Protein Target
A daily range scaled to your body weight and goal, not a flat number. It runs higher during a deficit, to protect muscle while calories are down, and more moderate during a surplus or maintenance.
Weekly Pace & Timeline
How fast the goal happens at a sustainable rate, about 1 lb/week for fat loss and 0.4-0.5 lb/week for muscle gain, and how many weeks that puts you at based on the total change you're aiming for.
How to Use These Numbers
- Start with the estimate, not perfection Use it as a starting range for two to three weeks before deciding whether it's working.
- Track weekly averages, not daily swings Water, sodium, and food volume move the scale day to day. The weekly trend is the real signal.
- Adjust from evidence, not willpower If the trend doesn't match the expected pace after a few weeks, change the calorie target, not your discipline.
Questions About This Calculator
How accurate are these numbers?
Mifflin-St Jeor is accurate within about 10% for most people, but it's a population-average formula, not a measurement of you specifically. It doesn't know your muscle mass, hormone levels, or metabolic history. Treat the result as a starting estimate to test against real results over two to three weeks, not a lab reading.
Why does this use the Mifflin-St Jeor equation instead of others?
Mifflin-St Jeor has been validated against measured metabolic rate more consistently than older formulas like Harris-Benedict (from 1919, revised in 1984), and tends to track closer to actual measured BMR in modern populations. It's the default most dietitians and exercise physiologists use today.
Does this calculator account for muscle mass?
Not directly. Mifflin-St Jeor uses total body weight, not lean body mass, and muscle burns more calories at rest than fat does. So a more muscular person's real BMR will likely run a bit higher than the estimate, and a higher body-fat percentage will likely run a bit lower.
What activity level should I pick if I'm not sure?
Most people overestimate it. If you have a desk job and train three to four times a week, "Lightly Active" is usually more accurate than "Moderately Active." When in doubt, pick the lower option, you can always adjust upward if your real-world results move faster than the estimate predicts.
Should I recalculate as my weight changes?
Yes. Both BMR and TDEE drop as you lose weight, since a smaller body needs fewer calories to run. Recalculating every 10 to 15 pounds of change keeps your targets current instead of stalling out on numbers that no longer match your body.
What if my real-world results don't match the estimate?
That's normal, and expected. This is a population-average formula, not a measurement of you. Give it two to three weeks, track the weekly trend, and adjust calories up or down by 100 to 200 based on what's actually happening, using the calculator's number as your starting point rather than a fixed rule.
