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Maintenance calories calculator

Your body uses energy to keep you alive, even when you are completely resting. That figure of energy use is your basal metabolic rate (or BMR), and it makes up the largest share of the calories you use in a single day.

Your maintenance calorie needs are higher than your BMR because they also include the energy you use through movement, exercise, and digestion.

Knowing roughly how much energy your body uses at rest can be useful information during weight maintenance. Our calories calculator helps you estimate maintenance calories from a few basic details.

Maintenance calories calculator

Find out roughly how many daily calories you need to maintain your weight loss.

170cm

70kg

This calculator provides estimates based on the Mifflin-St Jeor equation. For personalised advice, consult a healthcare professional.

What does BMR mean?

BMR is the number of calories your body uses to carry out its essential functions while you are at complete rest. That includes breathing, regulating your body temperature, and keeping your brain, kidneys, and other organs working.

For most people, BMR accounts for around 60% to 75% of the total energy they use each day. The rest comes from digesting food and from physical activity.

Your BMR is not something you can choose or control directly. It reflects your body size, composition, age, and sex, along with factors that are largely outside your influence.

BMR vs RMR

You may also come across resting metabolic rate, or RMR. The two are closely related and the terms are often used interchangeably, but they’re measured differently.

BMR is measured under strict conditions:

  • after an overnight fast
  • following a full night’s rest
  • in a temperature-controlled room
  • before any physical activity

Because those conditions are difficult to arrange outside a laboratory, true BMR is rarely measured directly.

RMR is measured under less restrictive conditions and is easier to obtain in a clinical setting. It usually comes out slightly higher than BMR because the body is not quite as fully at rest.

In everyday use, and in calculators like ours, the two are close enough that the distinction rarely matters.

How is BMR calculated?

The most common way to estimate BMR is an equation called the Mifflin-St Jeor formula, which is what our calculator uses. A systematic review found it to be among the most reliable of the equations commonly used in clinical practice. It estimates your BMR from four variables.

  • Weight: Body weight is the single largest influence on BMR. A larger body has more tissue to maintain, so it uses more energy at rest. This is why BMR estimates tend to fall as weight decreases.
  • Height: Height also contributes to BMR, as taller people generally have a greater surface area and larger organs, both of which increase resting energy use.
  • Age: BMR tends to decline gradually with age, partly because muscle mass typically decreases over time.
  • Sex: Men usually have a higher BMR than women of the same height, weight, and age. This mainly reflects differences in average body composition, as men tend to carry proportionally more muscle mass.
  • Body composition: The standard equation does not account for body composition directly, but it matters. Two people of the same weight, height, age, and sex can have meaningfully different BMRs if one carries considerably more muscle than the other.

Together, these factors provide an estimate of your BMR, but your actual energy needs can vary from the figure calculated.

BMR during the maintenance phase

Once you reach a weight you are happy with, your energy needs will be different from when you started. A smaller body uses fewer calories at rest, so the figure that applied at the beginning of treatment no longer will apply.

Also, after significant weight loss, BMR can fall by more than body size alone would predict. This is an effect sometimes called metabolic adaptation. For some people, this means resting energy use settles lower than a calculator would estimate.

Knowing roughly where your BMR sits can help you understand why maintenance feels different from losing weight. It is useful as background, rather than as a target.

We would encourage you to treat the number as one piece of information among many, and to approach it in moderation. How you feel, how your energy levels are holding up, how you are sleeping, and whether you can sustain your routine long term matter at least as much as any figure!

Counting calories does not suit everyone, and for some people it is unhelpful. If tracking feels difficult, or you find yourself thinking about it more than you like, speak to one of our clinicians. There are other ways to approach maintenance, and they can talk through what might work better for you.

"Your BMR can be a useful tool for understanding how much energy your body needs at rest, but it's not a number you need to manage obsessively. To maintain your weight successfully, it’s much more important to focus on sustainable habits, such as staying active, eating a balanced diet, and responding to your body's changing needs over time. When those habits are in place, the numbers tend to take care of themselves."

Niya Mansuri, Weight Loss Expert at myBMI

How accurate is BMR?

The figure our calculator gives you is an estimate and not a measurement. Equations like Mifflin-St Jeor are built from population averages, so they describe a typical person of your height, weight, and sex rather than you specifically.

Research has found that estimated BMR can differ meaningfully from measured BMR. Accuracy also tends to be lower in people living with obesity than in those who are not, whichever equation is used. Several factors contribute to that gap:

  • Body composition: muscle uses more energy at rest than fat tissue, and fat-free mass is one of the strongest predictors of measured BMR. This means that people with more muscle than average will tend to have a higher BMR than an equation predicts
  • Genetics: resting metabolic rate varies between individuals for reasons that are not fully understood
  • Hormones: thyroid function has a substantial effect on resting energy use
  • Health conditions and medication: a range of conditions and treatments can raise or lower BMR
  • Recent weight change: BMR may sit lower than predicted following significant weight loss

If you want to measure your resting energy use more precisely, indirect calorimetry is a clinical method that can be used. It involves analysing the oxygen you use and the carbon dioxide you produce while at rest, and it is available through some clinical and sports science services.

For most people, though, that level of precision is not necessary. An estimate tends to be enough for general orientation.

Next steps

Your BMR is a useful starting point for understanding how your body uses energy, and it can help explain why maintaining a weight may feel different from losing it. However, it’s not a rule to follow.

Maintenance works best when it is built on habits you can keep up, rather than just a number you are trying to hit. That means:

  • eating in a way that feels sustainable
  • keeping some form of regular movement in your week
  • getting support when you need it

You may also find our BMI calculator useful alongside this one, as the two give you different pieces of the same picture.

If you are moving into maintenance, or thinking ahead to it, our clinicians can talk you through what that might look like for you.

View our expert guide on maintaining weight loss for good

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