How to find your real maintenance calories
Calorie calculators give a starting estimate, often within about 10%. A few weeks of food logs and weigh-ins reveal your real maintenance. Here is how.
How accurate are calorie calculators?
Of the common equations, Mifflin–St Jeor predicts measured resting metabolic rate within 10% for the largest share of adults. That makes it the right place to start. It still leaves real error for any one person, and it’s less accurate for very muscular people, older adults and some ethnic groups.
To get from resting energy to maintenance, calculators multiply by an activity factor. Those multipliers, and the calorie numbers on watches, carry big individual errors of their own.
| Formula says | ±8% | ±15% |
|---|---|---|
| 2,000 | 1,840–2,160 | 1,700–2,300 |
| 2,500 | 2,300–2,700 | 2,120–2,880 |
| 3,000 | 2,760–3,240 | 2,550–3,450 |
Use your own logs and weigh-ins
Your weight trend against what you ate shows what you actually burn. That’s energy balance. If you logged about 2,500 kcal a day for three weeks and your smoothed weight held steady, your maintenance is close to 2,500 kcal, whatever the calculator said.
Now say that on the same 2,500 kcal, your trend fell by about 0.3 kg a week instead. At roughly 7,700 kcal per kg, that’s about 330 kcal a day of deficit (0.3 × 7,700 ÷ 7). So your maintenance is nearer 2,830 kcal.
| Smoothed trend | Implied gap | Your maintenance |
|---|---|---|
| −0.5 kg a week | 550 kcal deficit | 3,050 kcal |
| −0.3 kg a week | 330 kcal deficit | 2,830 kcal |
| Flat | None | 2,500 kcal |
| +0.3 kg a week | 330 kcal surplus | 2,170 kcal |
Your food log has to be complete
The number you get is only as good as your food log. Under-log consistently and your maintenance looks lower than it is.
And the scale moves by a kilogram or more day to day with water, glycogen and salt. Use a trend over at least two weeks. Two weigh-ins won’t do it.
Why your maintenance keeps moving
As you lose weight you need less energy, and some adaptation kicks in. That’s why the flat “3,500 kcal per pound” or “7,700 kcal per kg” rule overstates long-term loss.
The fix is a closed loop. Compare the rate you planned with the rate you measured, and correct.
What Laroa does with this
Laroa starts from Mifflin–St Jeor, then blends in the maintenance implied by your own logs and weigh-ins, weighted by how precise each one is. A patchy log or a noisy scale keeps the estimate closer to the formula for longer. Any change to your calorie target arrives as a proposal with this evidence, and you accept or decline it.
Common questions
Are TDEE calculators accurate?
They’re a reasonable start. They aren’t a measurement. The best equation is often within about 10% of measured resting energy, and the activity multiplier adds more error. A few weeks of your own data beats any calculator.
How long until I know my real maintenance?
A few weeks of reasonably complete food logs and regular weigh-ins. The scale is noisy day to day, so judge it on a trend of at least two weeks.
Are the calories on my watch reliable?
Calorie estimates from wearables carry large individual errors. Treat them as rough, and let your weight trend against your intake tell you what you burn.
The evidence behind this guide
Each claim above traces to an entry in Laroa’s evidence base (version 2026-10-17.1), which summarises position stands, guidelines and meta-analyses and grades how strong each one is.
- Estimating resting energy expenditureStrong evidence
- Measured maintenance beats formulasStrong evidence
- Weight change is not linearModerate evidence
- Daily weight noiseModerate evidence
Sources
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. doi:10.1093/ajcn/51.2.241
- 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;105(5):775-789. doi:10.1016/j.jada.2005.02.005
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837. doi:10.1016/S0140-6736(11)60812-X
- Trexler ET, Smith-Ryan AE, Norton LE. Metabolic adaptation to weight loss: implications for the athlete. J Int Soc Sports Nutr. 2014;11:7. doi:10.1186/1550-2783-11-7
- Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. doi:10.1093/ajcn/56.1.292S
General information for healthy adults, not medical advice. If you have a medical condition, are pregnant, or have pain or warning symptoms, ask a clinician.
