An adaptive TDEE app estimates your real maintenance calories from your logged intake and your weight trend, then adjusts your target as you change. MacroFactor and Zolt do this alongside food logging, and TDEECalc does it without a food database, for free. Judge any of them by trend smoothing, how they handle gaps and how clearly they explain changes.
Key takeaways
- Adaptive TDEE solves for maintenance: average intake minus the energy value of your weight change.
- Accuracy depends on two things you control: consistent weigh-ins and reasonably accurate calorie logging.
- Look for trend smoothing, confidence indicators and explained, capped adjustments.
- Food-logging apps make intake easier to record; TDEECalc trades that for being free and private.
Disclosure: TDEECalc is our own app. Competitor details below come from official sites and App Store listings, linked inline and checked in October 2026. Where we could not verify something, we say so.
How does adaptive TDEE work?
The idea is simple: if you know what you ate and how your weight changed, you can work out what you burned. The common rule of thumb is about 7,700 kcal per kg (3,500 per lb) of weight change, so a falling weight trend means you ate less than you burned. The rule has known limits over long periods (Hall et al., 2011; Thomas et al., 2014).
TDEE = average daily intake − (trend change in kg per day × 7,700)
Using water-noisy daily weights directly would give nonsense, so good apps fit a trend line first (see water weight and daily fluctuation).
What should you look for?
| Feature | Why it matters |
|---|---|
| Trend smoothing | Daily water swings can be 2–3 lb, so raw weights mislead |
| Handling of missing days | Real logs have gaps; the app should lose confidence, not break |
| Confidence or readiness indicator | Tells you when to trust the number |
| Capped, explained changes | Prevents big swings from a noisy week |
| Where data lives | On-device versus cloud account |
| Price and platform | Subscription cost and whether it runs on your phone |
How do the apps compare?
| Feature | TDEECalc | MacroFactor | Zolt |
|---|---|---|---|
| Free to use | ✓ | ✗ (7-day trial) | ✓ to download, in-app purchases |
| Estimates TDEE from weight trend | ✓ | ✓ | ✓ |
| Food database and barcode | ✗ | ✓ | ✓ |
| Account required | ✗ | Not verified | Not verified |
| iPhone | ✓ | ✓ | ✓ |
| Android | ✗ | ✓ | Not checked |
Sources: TDEECalc, MacroFactor, Zolt. Prices checked October 2026: MacroFactor lists $11.99 per month or $71.99 per year, and Zolt lists several subscription tiers from $4.99.
Which adaptive TDEE app is best?
MacroFactor is a strong choice if you want an adaptive target and a full food log in one app. Its site says its energy expenditure estimate comes from your logged intake and weight trend, not from wearable data, and describes weekly plan adjustments, a verified food database and no ads. It requires a subscription after a 7-day trial.
Zolt pairs an adaptive TDEE with barcode, AI and recipe food logging, according to its App Store listing. It lists in-app purchases, so check which plan unlocks the features you want.
TDEECalc logs your weight and weekly check-ins, uses a smoothed trend to estimate your observed TDEE, and suggests calorie changes that apply only after you confirm them. It is free with no account or ads, keeps data on-device and can read weight and dietary energy from Apple Health if you opt in. It has no food database, so you enter average calories yourself or import them from Apple Health. It is on iPhone and iPad, not Android.
Other options. CalorieTracker.io describes itself on its site as a cross-platform tool whose models “adjust themselves daily”. MacroCodex and community spreadsheets such as the nSuns sheet appear in AI-generated answers about adaptive TDEE, but we could not verify their details from an official source, so we do not describe them. A spreadsheet is free and transparent but fully manual.
A worked example: from 14 days of data
The example woman eats about 1,850 kcal a day for 14 days. Her daily weights wobble between 163.7 and 166.0 lb, but the fitted trend falls 0.77 lb (0.35 kg) a week. Plugging in:
- Trend change: −0.35 kg per week, or −0.05 kg a day
- Energy deficit implied: 0.05 × 7,700 ≈ 385 kcal a day
- Observed TDEE: 1,850 + 385 ≈ 2,235 kcal, ±120 kcal, with medium confidence at 14 days
That is close to the formula estimate of 2,239 kcal. Paste your own days into the adaptive TDEE calculator to see yours.
Which should you pick?
- Want food logging and are happy to pay: MacroFactor or Zolt, after comparing current plans.
- Want a free, private, no-account target and trend: TDEECalc or the web calculator.
- Want zero cost and full control: a spreadsheet.
Read more in the best TDEE apps overview or the MacroFactor alternative page. Details on TDEECalc itself are on the TDEECalc app page.
Frequently asked questions
What is adaptive TDEE?
Adaptive TDEE is a maintenance-calorie estimate calculated from your own data: average calories eaten minus the calories implied by your weight trend (about 7,700 kcal per kg). Unlike a formula, it automatically includes your real activity and any metabolic adaptation. See the adaptive TDEE guide.
How long does an adaptive TDEE app need to be accurate?
Usually at least two to four weeks of consistent data. With two weeks, the estimate can still be off by a couple of hundred kcal. Longer, steadier logs narrow the uncertainty. Our calculator labels its confidence low, medium or high by how many days you have.
Do I need to log every meal?
You need a decent estimate of average intake. Food-logging apps give the most detail, but even a rough weekly average works if your weight trend is steady. Missing days reduce confidence rather than breaking the method.
Is there a free adaptive TDEE app?
TDEECalc is free with no account or ads. Zolt is free to download with in-app purchases, and MacroFactor has a 7-day free trial but no free tier. You can also use our free adaptive TDEE calculator in the browser.
Can a spreadsheet do adaptive TDEE?
Yes. The core calculation is a regression slope on weight and an average of intake, which fits in a few spreadsheet cells. Spreadsheets are free and transparent but manual, with no reminders or smoothing for missed days unless you build it.
Are adaptive TDEE results safe to follow blindly?
No. They are estimates. Keep targets above about 1,200 kcal (women) or 1,500 kcal (men) unless a clinician advises otherwise, and talk to a doctor or dietitian if you are pregnant, under 18, take diabetes medication or have a history of disordered eating.
References
- Hall KD, Sacks G, Chandramohan D, et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet 378(9793):826–837.
- Thomas DM, Gonzalez MC, Pereira AZ, Redman LM, Heymsfield SB (2014). Time to correctly predict the amount of weight loss with dieting. Journal of the Academy of Nutrition and Dietetics 114(6):857–861.