TDEE Macro Calculator

Calorie and macro targets on most fitness apps are black boxes: a number appears with no explanation of how it was derived or which assumption has the most leverage on the final value. The Mifflin-St Jeor formula with activity multipliers is the most empirically validated baseline for estimating maintenance calories, but the activity multiplier alone can shift the total by 800 or more calories per day. This calculator makes the formula explicit, shows how each input contributes to the result, and lets you apply a deficit or surplus so the output is a meaningful starting point for nutrition planning rather than a number to accept on faith.

Best practices

• TDEE estimates are starting points, not prescriptions. Track intake and body weight for 2–3 weeks and adjust by 100–150 kcal based on whether you are gaining, losing, or maintaining at the target.
• The activity multiplier has the largest single effect on the result: an error here shifts total calories by 400–800 kcal/day. When in doubt, choose a lower multiplier and add calories back if recovery or performance suffers.
• Avoid deficits larger than 20% below maintenance for extended periods. Aggressive cuts increase muscle loss, reduce training performance, and are harder to sustain.