Net Calories (TEF) Estimator

First, it estimates TEF by applying a TEF “burn rate” that depends on your chosen macro profile (higher for protein, moderate for carbs, lower for fat), then multiplies that rate by the gross calories. Next, it applies an activity multiplier (and a meal-size assumption) to estimate additional energy cost associated with the food event. Net calories are calculated as: Net = Gross − TEF calories − Activity calories, with a floor at zero.

TEF differs widely by person, food processing, digestion speed, and how soon after eating you’re active, so this tool uses simplified averages from macro and meal type. The activity multiplier is not your measured daily expenditure—it’s a rough event-level offset—so it works best for comparing foods you’re deciding between rather than predicting total daily burn. Use the uncertainty setting to widen or narrow the likely range of outcomes.

If you enter very low gross calories, TEF can become a large fraction of the total; the calculator still prevents net calories from going below zero. For snacks, the activity adjustment is capped so you don’t end up overstating post-meal expenditure from a small eating event. If your custom macro profile is used, it must total 100% so the TEF blend is internally consistent.

This is an estimate, not a physiological measurement, and it does not replace tracking your full daily energy expenditure (NEAT, workouts, basal metabolism, and beyond). Treat label calories as the starting point even though real-world absorption and labeling accuracy can differ. The “highly efficient adjustment” or “minimal adjustment” label is directional—use it to compare options, not to make strict medical or performance decisions.