Calorie calculator: estimate your maintenance calories

Which calorie calculation do you need?

If you want an estimate of how much to eat, choose the tool by the output you need:

The calculator on this page uses Mifflin–St Jeor resting energy multiplied by your selected activity assumption. It does not measure expenditure or select a weight-loss reduction. Mayo and NIDDK are external tools with different models; this calculator is not the NIDDK Body Weight Planner.

If you want the calories in lunch, you need ingredients or food entries, quantities and nutrition values instead. A body-size equation cannot calculate a plate of food. The homemade food calculation guide covers that task.

If you want to total food already eaten, use a diary. The intake guide explains the quantity arithmetic and completeness checks. A diary total and a personal-needs estimate can then be compared, with their limitations intact.

What information goes into a personal calorie calculator?

Have your measurements ready before choosing a result:

Do not mix units inside a formula. A calculator may accept pounds on screen, but the equation below uses kilograms. Likewise, 5 feet 11 inches cannot be entered as 5.11 centimeters or 5.11 feet.

Keep the equation and activity choice visible when comparing tools. Two different estimates may come from different models or assumptions, even when you typed the same age and weight.

How does the resting-energy equation work?

The Mifflin–St Jeor study developed a resting-energy equation from 498 healthy adults aged 19–78. Its simplified forms are:

• Male equation: resting energy = 10 × weight in kg + 6.25 × height in cm − 5 × age in years + 5.
• Female equation: resting energy = 10 × weight in kg + 6.25 × height in cm − 5 × age in years − 161.

The output is kcal/day at rest. The sex categories come from the original equation; this is not an individualized assessment of every person's physiology. A generic formula may be a poor fit when individual circumstances differ from its underlying population or assumptions.

For an illustrative 35-year-old adult weighing 80 kg and measuring 180 cm, the male equation gives:

10 × 80 + 6.25 × 180 − 5 × 35 + 5 = 1,755 kcal/day.

This is a worked calculation, not a recommendation that this person eat 1,755 calories. Total daily energy expenditure also needs an activity assumption. A resting estimate is not a universal minimum-intake rule either.

How does activity change the maintenance estimate?

A simple planning method multiplies resting energy by an activity factor. The factor is an assumption about total daily demands; it is not a measurement from the resting equation itself.

Continue the example using an explicitly illustrative factor of 1.4:

1,755 × 1.4 = 2,457 kcal/day, or about 2,450 kcal/day when rounded to the nearest 50.

Using a different assumed factor changes the estimate:

These are sensitivity examples, not activity categories assigned to you. They show why choosing an assumption matters. Do not treat a rounded number as a validated uncertainty interval, and do not mix an activity scale from one tool into another model without checking its definition.

For a starting calculation, use the activity descriptions supplied by the tool you chose. Describe both the workday and leisure activity. If two descriptions seem plausible, compare both outputs and retain which description produced each; do not average them into a result with invented certainty. If usual exercise is already represented there, adding that exercise again changes the calculation and may count the same activity twice.

How do you use your maintenance calories?

Read the estimated daily maintenance output. That is the approximate food-energy intake associated with holding your current weight under the activity assumption you entered. The lower resting-energy number is not your maintenance intake.

1. Keep the inputs, activity multiplier and date beside the estimate. If maintaining weight is your goal, use the maintenance output as a starting planning number rather than adding a reduction.
2. Compare a sufficiently complete food record with consistently collected body-weight observations over time. A single weigh-in or partial diary cannot establish maintenance.
3. If the pattern does not fit the estimate, check missed food, portion uncertainty and changes in activity before adjusting the planning number. Revisit the estimate when your body size or routine changes.

For example, the worked case above gives 1,755 kcal/day at rest × 1.4 = 2,457 kcal/day estimated maintenance. These are illustrative inputs, not a target for every person with that age. A maintenance estimate is a starting reference; it is not proof that eating that amount will keep your weight unchanged.

To total what you actually ate, use the recorded-intake guide. If you want a starting loss-phase intake instead of maintenance, use the weight-loss calorie calculator. Keeping these tasks separate prevents a diary total from being mistaken for your energy requirement.

How do you turn maintenance into a goal?

For maintenance, the total daily estimate is the starting number. Weight-loss planning adds a chosen reduction; gaining weight requires a different plan. A calculator does not decide whether a goal is appropriate or whether the resulting intake supports a suitable diet.

Use the daily calorie needs guide to interpret a maintenance estimate in your routine. For loss-target decisions, continue with how many calories to eat to lose weight. The existing deficit arithmetic guide distinguishes a planned gap from intake and diary remainder.

Goal models should also state their limitations. A display saying how long a goal might take is a projection under assumptions, not a guaranteed date. A tool with a detailed chart can still be inappropriate for a particular reader.

How do you check the result before using it?

Read the output label: is it resting energy, maintenance or a goal-phase intake? Check the inputs and units, then inspect the activity definition. If the result seems surprising, those checks come before deciding the number must be correct or wrong.

Save the input assumptions with the estimate and review them when body size or routine changes. A food record can show what you entered, but it cannot verify expenditure by itself. Compare it with appropriate progress observations and obtain individual guidance when health or other circumstances make the estimate difficult to interpret.

IZeat is the five-star chef calorie tracker that suggests satisfying, great-tasting meals, so you enjoy every calorie you have left. It stores the target you choose and meals you record. You can ask your assistant to retrieve intake and discuss it alongside a planning estimate. The calculator on this page provides a separate planning estimate; it does not update your IZeat target. The food journal does not measure maintenance, store body-weight trends or certify that a diary day is complete.

The calorie-tracking pillar explains the recording method once you have a target.

Sources and method

Method: the on-page calculator uses Mifflin–St Jeor for resting energy and a selected activity multiplier for estimated maintenance. The multiplier is a planning assumption separate from the original resting equation. This maintenance view does not apply a reduction; the separate weight-loss page estimates a starting intake using a visible, editable reference reduction. Results are estimates, not measured energy use. Sources and external tool instructions were checked on 4 October 2026. The examples are declared arithmetic, not submitted external tool results or clinical validation.

• Mifflin et al., 1990: resting-energy prediction.
• Mayo Clinic: Calorie calculator.
• NIDDK Body Weight Planner.
• NIDDK: Planner scope.