How Does Garmin Calculate BMR? | What Your Watch Is Counting

Garmin estimates your baseline burn from your profile details, then turns it into “resting calories” that tick up through the day.

You see a number in Garmin Connect that looks like “baseline calories,” “resting calories,” or a daily total that climbs even on low-move days. It’s normal to wonder where that number comes from, and whether your watch is guessing or measuring.

Here’s the straight answer: Garmin starts with an estimated resting metabolic rate using details from your user profile (age, sex, height, weight). That estimate becomes the foundation for daily energy burn. Then your device layers in motion, heart rate, and activity data to build your total calories for the day.

People often say “BMR” as shorthand. In Garmin’s own wording, you’ll usually see “RMR” tied to resting calories, and Garmin notes that it slightly increases that resting estimate to account for sedentary-to-light movement across the day. You can read Garmin’s definitions in its Calorie Terminology page.

What Garmin means by BMR and resting calories

BMR is a lab-style concept: energy your body uses at rest under strict conditions. Most wearables don’t run a lab test on your wrist, so they rely on equations that estimate your baseline burn from body size and age.

Garmin presents that baseline as “resting calories.” It’s the part of your daily total that rises even when you’re not recording a workout. Garmin explains that resting calories are based on an RMR estimate derived from your age, height, weight, and gender, with a small bump added to reflect light movement through the day.

That framing matters because it explains two common surprises:

• Your resting calories can feel higher than a strict BMR calculator.
• Your daily total can climb steadily even on days that feel slow.

How Does Garmin Calculate BMR? What the numbers come from

Garmin doesn’t publish a single public equation that applies to every device and every mode. What Garmin does state plainly is the input set used for resting calories: age, height, weight, and gender. Those inputs feed an RMR estimate, then Garmin nudges it upward to reflect typical low-level daily movement.

From a practical angle, you can think of Garmin’s process in three layers:

1. Profile-based baseline: your resting estimate built from your demographic and body-size details.
2. All-day movement: accelerometer-based activity plus heart rate trends that shape how quickly total calories rise.
3. Workout periods: sport modes that use heart rate and activity type to estimate active calories, with a resting portion still present during that time window.

This is why the same person can see different totals on two platforms even on the same day. Apps may split “resting” and “active” differently, and some display the full day’s baseline upfront while Garmin’s total builds through the day.

Profile details that drive the baseline

Your watch can’t estimate a baseline without your profile data. If those fields are stale, the baseline can drift from reality for months.

These are the items that most strongly shape Garmin’s resting estimate:

• Weight: changes here can move resting calories fast.
• Height: often set once, then forgotten; a wrong value can skew the baseline.
• Age and sex: used in standard metabolic equations.

If you use a connected scale, Garmin can pull weight automatically, which reduces “stale profile” problems. If you don’t, set a simple routine to update your weight in Garmin Connect after meaningful changes.

Heart rate and motion: how Garmin builds total calories

Resting calories form the foundation. Total calories also include active burn. Garmin estimates active burn with sensor inputs that change by situation:

• All-day movement: step patterns and wrist motion push active calories up when you move around.
• Workout tracking: recorded activities use sport type plus heart rate behavior during the session.
• Heart rate reliability: tight fit and clean sensor contact can help, since poor contact can lead to odd heart rate readings that flow into calorie estimates.

On some devices and activity types, Garmin may use heart rate as the primary signal during exercise. On other activities, it blends heart rate with motion signals and the known energy patterns of that sport profile.

One more nuance: during an activity, the body would still be burning baseline energy. Garmin’s totals often include that “resting portion” inside the activity window, then separate views in apps may subtract it or display it differently. That’s one reason cross-app comparisons can feel messy even when both are “right” in their own display logic.

When Garmin’s baseline can look off

Even with correct profile data, your Garmin baseline can feel “too high” or “too low” for your lived experience. A few patterns drive that reaction:

Weight has changed and the profile didn’t

If your weight has shifted and the profile stayed the same, your resting estimate can lag behind your current body size. This is the top cause of mismatch for many users.

Body composition changes outpaced scale weight

Two people at the same weight can have different resting needs because fat-free mass differs. Most Garmin devices don’t build resting calories from a direct fat-free-mass lab measure. If your body composition shifted while weight stayed similar, the wearable’s baseline may not match what you feel day to day.

Daily movement patterns don’t match “sedentary to light” assumptions

Garmin states it bumps the resting estimate to account for low-level movement through the day. If your day is truly still for long stretches, that bump may feel generous. If your day includes lots of standing, walking breaks, and chores, it may feel closer.

Wrist heart rate quality is inconsistent

When heart rate readings jump around, active calorie estimates can swing. The baseline part stays steady, so the “weirdness” often shows up as active calories that don’t match effort.

What you can check inside Garmin Connect

You don’t need hidden menus to sanity-check the inputs Garmin is using. Start with these steps:

1. Open Garmin Connect and review your user profile for age, sex, height, and weight.
2. Confirm your device is syncing recent weight entries if you log weight elsewhere.
3. Compare a calm day to a busy day and look at how resting and active calories split.
4. Check that your heart rate graph looks believable during workouts.

If you want Garmin’s own navigation path for viewing calorie stats, Garmin documents where to find the calories screens in Viewing Calorie Data in Garmin Connect.

Now let’s put the moving parts into one place.

Input Or Signal	Where You Set Or Influence It	How It Changes Resting Or Total Calories
Age	Garmin Connect user profile	Feeds the resting estimate used to build resting calories
Sex	Garmin Connect user profile	Feeds the resting estimate; many equations differ by sex
Height	Garmin Connect user profile	Affects baseline energy needs tied to body size
Weight	Garmin Connect profile or connected scale	One of the fastest drivers of resting calories and daily total
All-day motion	Wear your device through the day	Adds active calories on top of resting calories
Wrist heart rate quality	Fit, placement, clean sensor window	Shapes active calorie estimates during exercise and some daily periods
Recorded activity type	Choose the correct sport profile	Changes how Garmin models effort and calorie burn for that session
Workout duration	Start/stop timing	Total calories include a resting portion during the activity window

How to get a cleaner baseline number from Garmin

You can’t force your watch to run a metabolic cart test. You can still tighten the inputs and reduce the common sources of drift.

Keep profile data current

If you’ve changed weight since you first set up the watch, update it. A stale weight is the easiest way to end up with a baseline that feels wrong.

Wear the device consistently

Garmin builds day totals from what it sees. If you only wear the watch for workouts, you’ll get workout estimates, yet all-day totals will reflect gaps. Consistent wear gives Garmin a steadier view of your daily motion patterns.

Improve heart rate contact during workouts

For many users, wrist heart rate is fine for steady cardio, and it can wobble during intervals, cycling on rough roads, or strength training with a tight grip. A snug fit above the wrist bone can help. Clean the sensor window if sweat and lotion build up.

Pick the closest activity profile

If you record indoor cycling as “cardio,” the calorie model can differ from what you’d see in a cycling profile. Choose the profile that matches the movement pattern and effort style you’re doing.

Use trends, not a single day

Daily calorie estimates will bounce with sleep, stress, and movement habits. If you’re using Garmin totals for weight management, look at weekly patterns and compare them against scale trends and food tracking trends.

How Garmin’s number compares to standard BMR calculators

If you plug your stats into a typical BMR calculator online, you might get a different baseline than Garmin shows as resting calories. That mismatch isn’t always a bug.

Standard BMR estimates are often presented as a pure “rest all day” number. Garmin’s resting calories are tied to RMR logic and include a small bump for low-level daily movement. Garmin’s terminology page spells out that difference in plain language.

If you want a plain-language refresher on what BMR means in medical terms and why equations are only estimates, Cleveland Clinic’s overview is a solid reference: Basal Metabolic Rate (BMR): What It Is & How To Calculate It.

What to do if your Garmin calories feel consistently off

If your Garmin totals don’t line up with your real-world results over weeks, don’t panic. Use a structured check so you’re not guessing.

Start by choosing a quiet two-week window. Keep your weight logging consistent. Track food intake with the same method each day. Wear the watch for most waking hours. Then compare the trend in your scale weight to the calorie balance implied by Garmin totals and your intake tracking.

If the trend is off, tighten the weak points first: profile fields, heart rate contact, and correct activity types. After that, treat Garmin’s calorie numbers as a relative meter: useful for comparing your own days and workouts, less useful as a lab-grade measurement.

If You Notice	Likely Cause	What To Try Next
Resting calories seem too high	Weight in profile is outdated or Garmin’s resting bump feels generous for your day	Update weight, review height, then compare a week of data instead of one day
Active calories look low during hard sessions	Wrist heart rate under-reads effort	Wear the watch snug above the wrist bone; check heart rate graph for dropouts
Active calories look high on easy sessions	Heart rate spikes from loose fit or motion noise	Tighten fit, clean sensor window, avoid wearing over a tattooed patch if possible
Totals differ a lot from another app	Different splitting of resting vs active, or baseline displayed upfront elsewhere	Compare a full past day and match “total calories” definitions across apps
Workout calories changed after switching activity type	Different sport model	Use the activity profile that matches your movement pattern and equipment

How to use Garmin’s baseline in day-to-day planning

Once you understand that Garmin’s resting calories are a profile-based estimate with a small daily-movement bump, the number becomes easier to use.

Here are a few ways readers tend to get the most value from it:

• Spot pattern changes: if your resting calories jump after a profile change, double-check the fields you edited.
• Compare your own weeks: use Garmin totals to see whether one week was genuinely more active than another.
• Check workout consistency: similar runs at similar heart rates should land in the same calorie range; huge swings often point to heart rate contact issues.

Garmin’s number won’t replace a lab measurement. It can still be a steady compass for your own habits once your profile is current and your sensor data is clean.