How to Change Calculations

Bevel lets you customize certain calculations, such as Heart Rate Variability (HRV) and Resting Heart Rate (RHR), so your data better reflects your personal goals and physiology. Adjusting calculations ensures that Insights, Trends, and recommendations are tailored to you.

This article explains how to view and update calculation methods in Bevel.

To update your calculation methods:

1. Open Bevel.

2. Tap your initials or profile picture in the top-right corner.

3. Tap Customization.

4. Tap Calculations.

From here, you can see the current method used for each calculation.

You can adjust calculations by:

1. Tap Method for the calculation you want to change.

2. Choose a new method from the available options.

3. Adjust where Bevel pulls the data from.

SDNN

• Uses HRV values already calculated and stored in Apple Health

• Apple Health uses the SDNN method to calculate HRV, but other devices may write to Apple Health using SDNN or RMSSD methods

• Best if you want Bevel to mirror Apple Health exactly

RMSSD

• Bevel calculates HRV using RMSSD (Root Mean Square of Successive Differences) for HRV. For supported newer Apple Watches, Bevel reads native Recovery HRV (RMSSD) data from Apple Health, along with beat-to-beat measurements provided by Apple, rather than calculating RMSSD entirely on its own.

• Provides a consistent and standardized HRV calculation that captures short-term difference

• For newer Apple Watches, such as Apple Watch Series 12 and Apple Watch Ultra 4, we recommend using RMSSD with Entire Sleep. This allows Bevel to take advantage of the more frequent 5-minute HRV readings collected by these newer models.

• Only applies for users with an Apple Watch where enough beat-to-beat samples are available

SDNN vs. RMSSD - what is the difference and why does Bevel use RMSSD?

RMSSD reflects short-term HRV and parasympathetic (rest/recovery) activity, making it ideal for daily recovery tracking.

SDNN captures overall HRV but is more influenced by long-term trends and less stable for day-to-day insights.

By default, Apple Watch measures HRV using SDNN. Bevel uses RMSSD because it’s better suited for assessing short-term recovery and sleep.

Newer Apple Watches, including Apple Watch Series 12 and Apple Watch Ultra 4, also measure Recovery HRV using RMSSD, with readings collected approximately every 5 minutes while at rest.

Entire Sleep (Recommended)

• Uses HRV data collected during your full Sleep window

• Produces the most stable and consistent Recovery Scores

• Best for day-to-day Recovery tracking

REM + Deep Sleep

• Uses HRV data only from REM and Deep Sleep Stages

• Can reduce noise but may result in less data on some nights

• Useful if you want HRV focused on deeper Sleep phases

Mindfulness Only

• Uses HRV recorded during mindfulness or breathing sessions

• Best if you consistently perform guided breathing or meditation

• Not recommended if mindfulness sessions are irregular

Entire Sleep + Mindfulness

• Combines Sleep HRV with mindfulness sessions

• Can provide more data points if mindfulness is done regularly

Entire Day

• Uses HRV data collected throughout the entire day

• Recovery Score may change as new data is recorded

Note: For the most consistent Recovery tracking, we recommend RMSSD + Entire Sleep for Apple Watch users, as it only uses data from your Sleep window and keeps your Recovery Score stable throughout the day.

Apple Health

• Uses resting heart rate values calculated by Apple Health

• Best if you want Bevel to match Apple Health exactly

Bevel

• Bevel calculates resting heart rate based on the average of heart rate samples in your selected data window

• Provides more control over how RHR is determined

Entire Sleep (Recommended)

• Uses RHR data collected during your full Sleep window

• Produces the most stable and consistent baseline

• Best for long-term Trend tracking

REM + Deep Sleep

• Uses RHR data only from REM and Deep Sleep stages

• Can reduce noise but may result in fewer data points on some nights

• Useful if you want RHR focused on deeper Sleep phases

Mindfulness Only

• Uses RHR recorded during mindfulness or breathing sessions

• Best if you consistently perform guided breathing or meditation

• Not recommended if mindfulness sessions are irregular

Entire Sleep + Mindfulness

• Combines Sleep RHR with mindfulness sessions

• Can provide more data points if mindfulness is done regularly

Entire Day

• Uses RHR data collected throughout the entire day

• May reflect overall daily Recovery and fatigue, but can be more variable

Note: RHR is also used in Cardio Load calculations. Changing your RHR setup may cause noticeable changes in Cardio Load metrics.

Wrist

• Uses wrist-based temperature measurements

• Most commonly available

Body

• Uses core/body temperature estimates when available

• May be more stable for some users

• Recommended if you use a wearable that is not on the wrist, such as a ring or chest strap

Choose the method that best matches the data your device reliably provides.

Entire Sleep

• Uses nighttime SpO₂ data only

• Best for consistent Trend tracking

Entire Day

• Uses all available SpO₂ readings

• May fluctuate more throughout the day

Entire Sleep

• Focuses on breathing patterns during Sleep

• Recommended for baseline tracking

Entire Day

• Includes daytime readings

• Useful if you want a broader view of respiratory changes

Total Calories

• Includes resting and active calories in Strain Trends

• Best for understanding overall energy expenditure

Active Calories

• Includes only calories burned from activity in Strain Trends

• Useful if you focus on workouts and movement

This is shown within Strain. Active Calories displays calories from recorded activities only, while Total Calories includes both Active Calories and Resting Energy.

Note: Calories in Nutrition and Net Energy will always show Total Calories vs. Calories Consumed.

Yes

• Manual Sleep entries are combined with tracked Sleep

• Useful if you occasionally forget to wear your device

No

• Manual Sleep entries remain separate

• Recommended if you want only device-recorded Sleep included

Once you’ve made your adjustments:

1. Tap Save in the top-right corner.

Your updated calculation settings will now be applied throughout Bevel.