Adaptive TDEE tracker
Formulas estimate from a population average. Your scale and your food log are about you. Log two weeks of weight and calories and get a number built from your own data.
Observed TDEE
This tracker runs in your browser and needs JavaScript. Log at least 14 days of morning weights and daily calories; the page then fits a line through your weights and estimates the calories you burn from your own data.
| Date | Weight | Calories | Actions |
|---|---|---|---|
| No days logged yet. | |||
Every TDEE calculator, this one included, is an educated guess with an error band of at least ±10%. For a TDEE of 2,300 that is a range of 2,070 to 2,530 kcal, which is the difference between losing a pound a week and losing nothing. The closest you can get to your own number at home is to compare what you eat with what your weight does, and that estimate has its own limits: it depends on honest logging and on the 3,500 kcal per pound rule.
That is what this page does. Enter your morning weight and the calories you ate, one row per day. After 14 days the tracker fits a straight line through your weights (which smooths out water swings), converts the slope to calories with the 3,500 kcal per pound rule, and adds it to your average intake. The result is your observed TDEE. If you saved a baseline on the calculator, the page shows how far the formula was off.
How to log so the number is right
- Weigh in the same conditions every day: morning, after the bathroom, before eating, same scale. Daily weigh-ins are better than weekly because the line uses all of them.
- Count everything you eat and drink, including oil, sauces, alcohol and weekends. Under-counting is the usual failure: in a classic study, people who believed they could not lose weight under-reported their intake by an average of 47%. You do not need to be perfect, you need to be consistent.
- Keep your activity steady for the two weeks. A new training program or a vacation changes the thing you are trying to measure.
- Expect noise in the first week. Starting a deficit drops a few pounds of water and glycogen that are not fat; the line fitted across 14 or more days dilutes that, and 21 to 28 days is better still.
The math, in one line
observed TDEE = average daily intake − (weekly weight change in lb ÷ 7 × 3,500)
Lose 0.5 lb a week on 2,000 kcal and your TDEE is 2,000 + 250 = 2,250. Gain 0.5 lb a week on the same intake and it is 1,750. The 3,500 figure assumes the change is mostly fat; early water loss and muscle gain break the assumption, which is another reason to log longer rather than shorter.
What to do with the observed number
- If it is within the ±10% band of the formula, the formula was fine; keep the plan and keep logging.
- If it is lower than the formula, your activity level was probably one step too high, or intake was under-counted. Set your targets from the observed number from now on.
- If it is higher, you move more than the level implies. Enjoy the extra food and set targets from the observed number.
- Re-run every 10 lb. The tracker keeps every entry, so you can export the log to CSV and keep going.
Where the data lives
In your browser only. There is no account and nothing is uploaded; the log is stored with your other site data on this device and disappears if you clear it, so export a copy now and then. The export is a plain CSV with three columns (date, weight in lb, calories) that opens in any spreadsheet and can be imported back here or on another device.
Questions
How often should you recalculate your TDEE?
With a tracker, you do not recalculate: the number updates with every day you log, and it reflects the body you have now rather than a formula. Without one, re-run the calculator after every 10 lb or whenever your routine changes.
Is the observed TDEE more accurate than the calculator?
After three or more weeks of honest logging, yes, because it measures the result instead of predicting it. Its error comes from your logging, not from a population average. The two weaknesses are under-reported intake and short logs dominated by water changes.
Can I use kg instead of lb?
Yes, switch the unit above the form. Entries are stored in pounds and converted exactly for display, so you can change the unit at any time without losing anything.
By Alton Vieira · Updated . Estimates for healthy adults; not medical advice. How every number is calculated.
- Hall KD et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011.
- Lichtman SW et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med. 1992.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005.