How this calculator estimates your targets
Resting energy uses the Mifflin–St Jeor equation, then applies an activity estimate based on the workday setting and weekly training sessions. The chosen goal adjusts estimated maintenance calories; protein and fat are set from body weight and the goal, with remaining calories assigned to carbohydrates. Fiber and micronutrient references come from Speed Macros's versioned nutrition rules.
This calculator does not show weight-loss targets below a minimum daily level (the low end of the usual ranges in the 2013 AHA/ACC/TOS guideline), or below estimated maintenance when that is lower. When a weight-loss estimate is held there, the result says so.
A formula cannot measure your metabolism or predict your exact needs. Activity multipliers and food records introduce uncertainty, and calorie needs can change with health, medication, sleep, and daily movement. Track your own trend over time and adjust cautiously instead of treating one estimate as exact.
What does “optimal macros” mean?
There is no single optimal macro split for everyone. Protein needs depend on body size, training, energy balance, and health context. Carbohydrate and fat can vary within a balanced diet. This calculator shows one transparent starting point from its inputs and rules; it does not prescribe a diet or prove that a target is ideal for you. Read the guide to choosing macro targets for more context.
This general adult tool is not designed for people under 18, pregnancy or breastfeeding, eating-disorder care, or treatment of a medical condition. Ask a registered dietitian or clinician for individualized guidance.
- Jensen et al. (2014): 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults
- Mifflin et al. (1990): a predictive equation for resting energy expenditure
- Morton et al. (2018): protein supplementation and resistance-training outcomes
- International Society of Sports Nutrition position stand: protein and exercise
Calculation rules: Speed Macros nutrition rules version 2026.10.14. Last editorial review: October 11, 2026. No registered dietitian review is claimed.