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Your calorie estimate is a starting point: how to check and adjust it

Last updated: October 8, 2026. Written by JAE's AI Consulting Solutions.

What the Mifflin-St Jeor equation was built on, why two calculators disagree, and how to move the offset on the TDEE page without turning it into a promised rate of weight change.

Estimate only, not medical advice. This does not diagnose or treat any condition or replace a doctor or registered dietitian. If you are pregnant, under 19, managing a medical condition or an eating disorder, or on a prescribed diet, get individual guidance.

A calculator answer is a hypothesis

A maintenance estimate answers a narrow question: given this equation, these body inputs, and this activity factor, what daily calorie figure does the arithmetic produce? It does not weigh your food, read a step counter, or watch what happens on the scale next month. The useful habit is to write down which inputs you used, eat in the neighborhood of that figure long enough to see a pattern, and then change one input on purpose if the pattern is not the one you are watching for.

The TDEE calculator is built for that loop. It shows resting energy (BMR in the label on the page), maintenance after the activity factor (TDEE), and an adjusted target if you type an offset. A negative offset lowers the target. A positive offset raises it. The page keeps the unrounded figures in the breakdown and rounds the big headline to the nearest 10 kcal. When you compare two weeks, compare the same kind of number each time, either the unrounded product or the headline, and say which one you are following.

The Dietary Guidelines for Americans, 2025–2030, say the calories you need depend on your age, sex, height, weight, and level of physical activity. Those are the kinds of inputs on the form. The activity multipliers themselves are a separate choice. The five factors on the page, 1.2, 1.375, 1.55, 1.725, and 1.9, are a common convention. They are not a figure from the 1990 paper and they are not a figure from the Dietary Guidelines. Picking "moderate" is you describing your week. It is not a measurement the form can check.

What the 1990 abstract actually reports

Mifflin, St Jeor, and colleagues published the equation this page runs in the American Journal of Clinical Nutrition in 1990. The abstract, read from the NCBI record for PubMed 2305711 on October 8, 2026, says a predictive equation for resting energy expenditure was derived from 498 healthy subjects. That sample included 247 females and 251 males, ages 19 to 78 years, with a mean age of 45 years and a standard deviation of 14 years. It included 264 normal-weight and 234 obese participants. Resting energy was measured by indirect calorimetry.

The abstract reports one multiple-regression equation for men and women together, with an R² of 0.71:

REE = 9.99 × weight + 6.25 × height − 4.92 × age + 166 × sex (males, 1; females, 0) − 161

R² = 0.71 is a statement about how that regression fit that sample. It is not a promise that the next person's result will land within a named percent of a lab measurement. The abstract then says simplification of the formula, and separation by sex, did not affect its predictive value, and it prints the pair the calculator actually runs:

• Men: REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) + 5
• Women: REE = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (y) − 161

The same abstract says the Harris-Benedict equations derived in 1919 overestimated measured resting energy by 5 percent in that sample (p less than 0.01). That sentence is about the 1919 equations inside the 1990 sample. It does not rank every equation published since, and it does not say a home calculator that adds an activity factor inherits a 5 percent error bar. The calculator page repeats those limits. This guide does too.

The abstract also says fat-free mass was the best single predictor in the sample (R² = 0.64) and that adding relative body weight and body-weight distribution did not significantly improve the sex-specific equations. The TDEE form has no body-fat input. A tape-measure body-fat estimate, including the Navy method already on this site, stays on its own page. It does not revise the Mifflin result.

The arithmetic the TDEE page runs

Pounds become kilograms by dividing by 2.20462. Inches become centimeters by multiplying by 2.54. Feet and inches become total inches as feet × 12 + inches, then centimeters. The sex menu selects the +5 or the −161. Age is in years. Maintenance is that resting figure times the activity factor you select. The adjusted target is maintenance plus the offset you type, which is zero until you type one. Headlines round to the nearest 10 kcal. The breakdown keeps more decimals so you can see what the rounding did.

Two warnings use that same math. If the adjusted target is below the resting figure, the page says so. If the adjusted target is still at or above the resting figure, but nearest-10 rounding leaves the headline no higher than the resting headline, the page says the target is near the resting estimate. Neither warning invents a minimum calorie number. Both tell you the arithmetic has reached the resting estimate, and that the result is not a target to follow on your own.

Worked example: one man, five activity factors

Man, 30 years, 80 kg, 180 cm. The male equation is 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal. That resting figure is already a multiple of 10, so the headline stays 1,780. Every maintenance number below is 1,780 times the factor, which is the only line that changes.

The moderate row is the one the calculator's own worked example uses: 1,780 × 1.55 = 2,759, and the headline is 2,760. The sedentary and extra-active headlines are 2,140 and 3,380. That is a spread of 1,240 kcal on the headlines, from the factor alone, with height, weight, age, and equation held still. If another site prints a different maintenance for this same man, ask which factor it used and whether it rounded to 10 kcal, to 50 kcal, or not at all. Those three choices explain a lot of "the calculators don't match" before anyone argues about the equation.

Nothing in the table says the moderate row is the true burn for a person who calls their week moderate. The factor is a label you apply. If your week changes, you change the factor and you get a new starting estimate. You still check it.

Worked example: a smaller offset, and the offset that trips the warning

Woman, 35 years, 65 kg, 165 cm, light factor 1.375. Resting energy is 10 × 65 + 6.25 × 165 − 5 × 35 − 161 = 650 + 1,031.25 − 175 − 161 = 1,345.25 kcal. The resting headline rounds to 1,350. Maintenance is 1,345.25 × 1.375 = 1,849.72 kcal, and the headline rounds to 1,850.

Type an offset of −250 kcal. The unrounded target is 1,849.72 − 250 = 1,599.72. The headline rounds to 1,600. That target is still above the resting figure, and 1,600 is above the resting headline of 1,350, so the near-BMR warning stays off. This is a change you can see on the page. It is not a forecast of weight change.

Type −500 instead. The unrounded target is 1,849.72 − 500 = 1,349.72. The headline rounds to 1,350. The unrounded target is still a few tenths above 1,345.25, so the "below BMR" branch does not fire. The headlines match: both are 1,350. The page's second branch does fire. It tells you the adjusted target is near the resting estimate and is not a target to follow. That is the teaching case. A round −500 looked like a modest step next to an 1,850 headline, and the rounding plus the resting estimate said otherwise.

If you continue into the macro calculator with the 1,600 headline, 65 kg, 1.2 grams of protein per kilogram, and 30 percent of calories from fat, the macro page's own example applies: protein 78 g (312 kcal, 19.5 percent of 1,600), fat 53.3 g, carbohydrate 202 g. Feeding the unrounded 1,599.72 into the same gram rules still displays 78 g protein, 53.3 g fat, and 202 g carbohydrate at the one-decimal fat and carb display that page uses. The protein grams do not move because they come from 1.2 × 65, not from the calorie total. Fat and carbohydrate absorb the calorie difference, and at one decimal it is too small to show. Say whether you handed the macro page 1,600 or 1,599.72. The headline path is the one that matches the macro page's published example.

The 1.2 grams per kilogram used there is the low end of a sentence in the Dietary Guidelines for Americans, 2025–2030: protein serving goals of 1.2 to 1.6 grams of protein per kilogram of body weight per day, adjusting as needed based on individual caloric requirements. The protein intake calculator prints both ends. For 65 kg that is 78 g and 104 g. The macro example picked the low end and a fat share of 30 percent. Those are inputs, not a finding that this woman should eat that way.

Worked example: US units, and a headline that hides a small gap

Man, 30 years, 180 lb, 5 feet 10 inches. Total height is 70 inches. The page converts before the equation: 180 / 2.20462 displays as 81.647 kg, and 70 × 2.54 = 177.8 cm. The equation uses the unrounded kilogram quotient. Resting energy displays as 1,782.72 kcal, and the headline rounds to 1,780. Times the moderate factor 1.55, maintenance displays as 2,763.21 kcal, and the headline rounds to 2,760.

Set that next to the metric man above, who was 80 kg and 180 cm, not 180 lb and 70 inches. His unrounded moderate maintenance was 2,759 and his headline was also 2,760. Two different bodies, two unrounded products 4.21 kcal apart at the two-decimal display (2,763.21 and 2,759), one shared headline. If you are logging "2,760" you are logging the rounded line. If you are comparing calculators, compare the unrounded line too, or you will call a match what is only an agreement after rounding.

The same rounding is why the woman's −500 case deserves a second look. 1,349.72 and 1,345.25 are not the same unrounded number. Their headlines are the same 1,350. The warning is about that headline collision. Read the breakdown, not only the big type.

Why a second calculator prints a different number

Hold the person still and list the switches that move the result on this site alone. The equation switch is male versus female: +5 versus −161, a 166 kcal gap in the resting figure before any activity factor. The unit switch is the 180 lb man versus an 80 kg man: different kilograms, different centimeters, resting figures 1,782.72 and 1,780. The factor switch is the table above, from 2,136 to 3,382 before rounding. The offset switch is whatever you type. The display switch is nearest 10.

A calculator that uses a different resting equation, or that folds activity in some other way, will disagree even when every body measurement matches. The honest comparison is to recompute both with the formulas written on the page, not to average the two headlines and call the average more accurate. This site runs the simplified sex-specific Mifflin equations and the five conventional factors. If you want a different equation, this is the wrong page to average it with.

Age belongs in the same list. The sample stopped at 78 and started at 19. The form still calculates outside that span and shows a warning. A different number from a pediatric tool, or from a clinician who measured resting energy, is not a glitch in the arithmetic. It is a different question.

The 3,500-calorie rule, and the planner NIDDK built instead

A fixed 3,500 calories per pound has been used for a long time to turn a daily deficit into a weekly weight change. NIDDK's Kevin Hall, in a July 11, 2018 explanation of the NIH Body Weight Planner, says that rule has been used for decades to relate diet calories to how body weight will respond, and that the body is not that simple. As the calories you consume change, the body responds in a way that offsets the calorie deficit over time, so weight loss slows and you lose much less weight than the 3,500-calorie rule promises. Hall describes the planner as a mathematical model, built from controlled studies of how calorie burning changes as people lose weight, that people can use for a more accurate prediction. He also describes it as the first tool that tells people what they have to do to keep weight off, not only what they have to do to lose it.

The public "About the Body Weight Planner" page says the planner lets users make personalized calorie and physical activity plans to reach a goal weight in a specific time period and to maintain it afterwards. The page's disclaimer, last reviewed May 2017, says the information is for adults 18 and older and not for younger people or for pregnant or breastfeeding women, and that it is not medical advice. A clinician who has examined you is the person who diagnoses and treats a health problem.

CalcHive does not run that model. The TDEE page stops at resting energy, maintenance, and the adjusted target. It will not tell you that an offset of 250 kcal produces a named change on the scale. If you want the model Hall is describing, use the NIDDK planner, and read its own limits. If you want the Mifflin arithmetic checked by hand, use the worked examples on this page and on the calculator.

A way to check the estimate, then move it

Pick one headline and live with it long enough to learn something. For the metric man at factor 1.55, that might be the 2,760 headline, with 2,759 written in your notes so you remember the unrounded product. For the woman, it might be 1,850, with 1,849.72 in the notes. Weigh at the same time of day, in similar clothing, under similar conditions, and keep the week's readings together. One morning after a salty meal, a hard workout, or a poor night of sleep is a single point. The pattern across the week is the check.

The site's average calculator will average a list of weigh-ins you type. This guide does not supply a sample weight series, because a made-up series would look like a rate of change. Bring your own readings. Average the week. Compare that average with the next week's average while the calorie target stays put.

If you decide to change intake, change the offset and leave the equation, the body inputs, and the activity factor alone, unless one of those was wrong. The woman's −250 case shows what "a smaller step" looks like inside this calculator: unrounded target 1,599.72, headline 1,600, warning off. The −500 case shows the step that collides with the resting headline. You can type any other offset. The page will do the same subtraction. It will not grade the offset as safe, fast, or appropriate.

Hold the new offset steady while you collect another set of same-time weigh-ins. Hall's point is that expenditure changes as intake and weight change, so a few days are a weak test of a fixed-calorie rule. This guide will not name a number of weeks that "should" be enough, and it will not name a pound change that "should" appear. If the weekly averages are moving in a way you did not expect, or if the warning near the resting estimate is on, stop treating the figure as a plan and get individual guidance. The red box at the top is the boundary: pregnancy, age under 19, a medical condition, an eating disorder, or a prescribed diet are reasons to leave the form and talk to a clinician or a registered dietitian.

Two more switches are easy to confuse with a real change in intake. Updating your body weight in the form changes the equation's output even when you eat the same food. Switching from factor 1.375 to 1.55 changes the starting estimate even when the week did not change. Write the factor and the weight next to the calorie number. Otherwise the next comparison mixes a new hypothesis with a new outcome.

What this guide will not do

It will not promise a rate of weight loss or weight gain. It will not turn 3,500 into a weekly pound target. It will not call Mifflin the most accurate equation in current use. It will not treat the activity factors as an official standard. It will not store your weigh-ins: the TDEE page calculates in the browser and does not use local storage. A link onward puts figures in the address bar so the macro page can fill its fields. That is a handoff on your device, described on the calculator page.

If the next question is grams rather than the calorie total, open the macro calculator with the calorie figure you actually intend to use. If the next question is grams of protein per kilogram, open the protein calculator and read both the 0.8 adult basis on its National Academies source and the 1.2 to 1.6 Dietary Guidelines range. If the next question is a week of meals you type yourself, the weekly meal planner sums those meals against a target. It does not generate recipes. The budget side of the same section, cost per gram and a family food bill, is the companion guide: budget high-protein meal prep.

FAQ

How accurate is a TDEE calculator?

The 1990 Mifflin-St Jeor abstract reports a regression fit of R2 = 0.71 on 498 healthy adults whose resting energy was measured by indirect calorimetry. That describes that sample. The CalcHive TDEE page then multiplies the simplified equation by an activity factor from a common convention, 1.2, 1.375, 1.55, 1.725, or 1.9, and rounds the headline to the nearest 10 kcal. Treat the result as a starting estimate and check it against weigh-ins you record yourself.

Why do two calorie calculators disagree?

They can use a different equation, a different activity factor, or a different rounding rule. On this site's TDEE calculator, the same 30-year-old man at 80 kg and 180 cm has an unrounded maintenance of 2,136 kcal at factor 1.2 and 2,759 kcal at factor 1.55. The headlines round those to 2,140 and 2,760. The gap is the factor you picked, not a second measurement of that person.

What did the Mifflin-St Jeor paper measure?

The abstract says the equation was derived from 498 healthy subjects, 247 female and 251 male, ages 19 to 78 years, including 264 normal-weight and 234 obese participants, with resting energy expenditure measured by indirect calorimetry. In that sample the Harris-Benedict equations from 1919 overestimated measured resting energy by 5 percent. The abstract does not call the new equation the most accurate equation in use today.

Why is a 3,500-calorie rule a weak plan for weight change?

NIDDK researcher Kevin Hall has explained that the body offsets a calorie deficit over time, so weight loss slows and the loss is smaller than a fixed 3,500 calories per pound promises. NIDDK's Body Weight Planner is the tool built to model that. The CalcHive TDEE page does not run that model and does not convert an offset into pounds.

How do I adjust the estimate?

Keep the equation, the body inputs, and the activity factor fixed. Change only the offset you type, then compare another run of same-time weigh-ins. In the woman's worked example, an offset of -250 kcal leaves an unrounded target of 1,599.72, which the page headlines as 1,600, and the near-BMR warning stays off. An offset of -500 kcal leaves 1,349.72, headlined as 1,350, and the warning turns on because that headline matches the headline of her BMR. This page does not say how many pounds either offset should produce.

What if I am under 19, over 78, or pregnant?

The 1990 sample was ages 19 to 78. Outside that range the calculator still runs the arithmetic and shows a warning. The NIDDK Body Weight Planner page says its information is for adults 18 and older and not for younger people or for pregnant or breastfeeding women, and that it is not medical advice. Pregnancy, breastfeeding, a medical condition, an eating disorder, or a prescribed diet need individual guidance.

Sources

Checked October 8, 2026. Activity factors are labeled as a common convention and are not given an official citation.

• Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. PMID 2305711, DOI 10.1093/ajcn/51.2.241. The abstract text used here (498 healthy subjects, 247 female and 251 male, ages 19–78 years, 264 normal-weight and 234 obese, indirect calorimetry, R² = 0.71, the regression equation, the simplified sex-specific equations, and the Harris-Benedict 5 percent overestimate in that sample) was read in the PubMed/NCBI record for PMID 2305711 on October 8, 2026. PubMed 2305711.
• Dietary Guidelines for Americans, 2025–2030. The line that calories depend on age, sex, height, weight, and level of physical activity, and the protein serving goals of 1.2–1.6 grams per kilogram of body weight per day, were read in the PDF on October 8, 2026. DGA PDF.
• Hall K. NIH Body Weight Planner. NIDDK, July 11, 2018. The transcript's description of the 3,500 calorie per pound rule, the body's offset of a deficit, and the planner as a model of that response was read on the page October 8, 2026. NIDDK transcript.
• About the Body Weight Planner. NIDDK. The description of personalized calorie and physical activity plans, the adult scope (18 and older; not younger people; not pregnant or breastfeeding women), and the statement that the information is not medical advice were read on the page October 8, 2026. The page's own last-reviewed line said May 2017. About the Body Weight Planner.

Related

• TDEE calculator for the equation, the five factors, and the offset field
• Macro calculator for grams from the calorie figure you chose
• Protein intake calculator for 0.8, 1.2, and 1.6 grams per kilogram
• Weekly meal planner to add meals you type against a target
• Budget high-protein meal prep: a cost-per-gram method
• Nutrition calculators

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