Compare assumptions
Try the activity level on either side of your choice. The comparison shows the effect of that assumption, not a personalised confidence range.
Switch calculator
ENERGY
TDEE calculator
Estimate your daily maintenance calories.
Your daily energy estimate
Resting energy and activity assumptions, explained.
Ready when you are.General information and estimates, not medical advice.
Use your result.
Keep the model in perspective
A calculator estimates resting energy and activity. Individual needs can differ, and a model that works for one population may fit another less well.
Use the right tool for the job
For a longer-term weight-management scenario, explore NIDDK’s Body Weight Planner. It uses a different, dynamic model; we do not send it your inputs.
BEHIND THE NUMBERSMethod & trusted reading
A starting point,
not a prescription.
TDEE estimates the energy you use across a day. We start with resting energy and apply the activity factor you choose.
The equation
The simplified Mifflin–St Jeor equation is 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for the male equation or minus 161 for the female equation. It estimates resting energy expenditure (REE), often called BMR in online calculators.
The activity assumption
We multiply resting energy by your selected factor: 1.2, 1.375, 1.55, 1.725, or 1.9. These broad planning assumptions are separate from the original resting-energy study. Compare levels to see how much this assumption changes the result.
Reading your result
This rounded estimate is not a measured requirement or a weight-loss target. Input limits are safeguards, not validation for every adult. This tool is not designed for pregnancy, breastfeeding, children, or medical nutrition planning.
Formula references
Documented 9 November 2026. No clinical review is claimed.
Read further.
Original research and official guidance. References do not imply endorsement of HandyShelf.
ORIGINAL STUDY
Where the resting equation comes from ↗
Mifflin and colleagues developed a resting-energy prediction equation. This is the source of the resting estimate, not of every activity assumption.
Mifflin et al. · 1990SYSTEMATIC REVIEWHow reliable are prediction equations? ↗
A review compares common resting-metabolic-rate equations and explains why individual errors still matter.
Frankenfield et al. · 2005NIH / NIDDKExplore a dynamic body-weight model ↗
An official interactive planner for adult weight-management scenarios, with its own scope and assumptions.
National Institutes of HealthATHLETE-SPECIFIC REVIEWWhen population matters ↗
A systematic review of athletes shows why a general-population equation should not be presented as universally accurate.
Systematic review · 2023Quick questions.
Is TDEE the same as BMR?
No. Resting energy is the starting estimate. TDEE includes daily activity through a separately chosen multiplier.
Why do calculators disagree?
Equations, activity factors, and assumptions differ. None measures your individual energy expenditure.
Which activity level should I choose?
Consider your whole day, not just a hard workout. The broad descriptions are assumptions; changing the factor illustrates its effect.