# Amazfit BioCharge vs Garmin Body Battery

> Both are 0-100 energy gauges. What Amazfit and Garmin actually publish about each, why BioCharge is now HybridCharge, and what a score can't tell you.

Published 2026-08-02, facts about other products checked 2026-10-09.

Canonical page: https://pulse.portlabs.in/blog/amazfit-biocharge-vs-garmin-body-battery/

Both are daily energy gauges that start from how you slept and drain as you move and stress. Garmin's Body Battery is older and built on Firstbeat's HRV analysis. Amazfit's BioCharge is newer, and by May 2026 it was reportedly renamed HybridCharge. Neither company publishes its formula, so you're comparing described inputs, not methods.

## What each one is

**Garmin Body Battery** arrived in 2018. Garmin's own page says it is powered by the Firstbeat Analytics engine and shows the effect of activity, stress, relaxation and sleep in one place. It reads heart rate variability, heart rate and movement, and it is modelled, not measured: no sensor reads "energy". The5krunner, citing the Fenix 8 manual, describes a 5 to 100 scale with bands of 76-100 high, 51-75 medium, 26-50 low and 5-25 very low.

*Figure: Garmin Body Battery scale from 5 to 100, split into very low, low, medium and high. Fenix 8 manual bands, as reported by the5krunner.*

**Amazfit BioCharge** launched around August 2025 on the Helio Strap. Amazfit describes it as an energy score built from sleep, heart rate, HRV, stress and daily activity. It updates through the day, where Amazfit's older Readiness score was a single morning figure. It then spread to the Balance 2 and, by the5krunner's April 2026 write-up, to nine models including the Active 3 Premium and T-Rex Ultra 2. That report says it replaced Readiness across the range from September 2025.

Then the name changed again. The5krunner reports that a score called HybridCharge replaced both BioCharge and Readiness in the Zepp app in May 2026, with bands of 0-59 poor, 60-79 fair and 80-100 good. No Amazfit support page confirming this could be found, so treat it as reported. Some watch faces may keep the BioCharge label until a firmware update arrives, which would explain why you still see both names.

*Figure: Amazfit HybridCharge scale from 0 to 100, split into poor, fair and good. HybridCharge bands as reported by the5krunner, not confirmed by Amazfit.*

## Side by side

| | Garmin Body Battery | Amazfit BioCharge / HybridCharge |
|---|---|---|
| Introduced | 2018 | BioCharge 2025, HybridCharge reported May 2026 |
| Scale | 5-100 (Fenix 8 manual, per the5krunner) | 0-100; HybridCharge bands 0-59 / 60-79 / 80-100 (reported) |
| Stated inputs | HRV, heart rate, movement, sleep, stress derived from HRV | Sleep, HRV, resting heart rate, stress, activity; HybridCharge adds self-reported "LifeLoad" ratings and workout effort (reported) |
| Engine | Firstbeat Analytics | Not named |
| Formula published | No | No |
| Validation published | No formal accuracy specification found | None found |
| Settling-in time | Roughly one to two weeks of wear (reported) | Weekly insights withheld for the first seven days (reported) |

## What is published, and what isn't

For Body Battery, the outline is public and consistent: HRV is the main driver, sleep is the main recharge, and stress and exercise drain. A full night can add something like 40 to 60 points (the5krunner's figure, not Garmin's). During a recorded activity the display freezes and the drain is applied when you save it. Firstbeat has published white papers on HRV-based recovery and stress analysis, and the5krunner points to a 2018 study by Pietilä and colleagues on alcohol's effect on heart rate and HRV in early sleep. What nobody has published is how those pieces are weighted into the single number.

For BioCharge, Amazfit publishes the list of inputs and the launch dates. It does not publish weights, a method or a validation study that could be found. HybridCharge is murkier. The self-reported part is the genuinely different idea: you rate eight areas of daily life (sleep, mood, nutrition, work and so on) as low, medium or high impact, and the app applies an adjustment on top of the biometric base without overriding it. The same article notes that Amazfit does not say how subjective and objective inputs are weighted, and that logging the same positive entries every day could flatter the score.

*Figure: Garmin and Amazfit both publish the outline of their scores but neither publishes weights. Garmin's page and the5krunner; Amazfit's launch coverage.*

Garmin's Lifestyle Logging is the nearest equivalent on the other side, but Garmin tags are used to find correlations over time. They don't change the Body Battery calculation.

## Why your number looks low

A few things drag either gauge down whatever the brand.

1. **Gaps in wear.** Both models lean on overnight HRV. If you take the watch off to charge it at night, you've removed the main input.
2. **A new baseline.** Both vendors, reportedly, need one to two weeks before the score reflects you. A low number in week one says little.
3. **Alcohol and late meals.** They can keep heart rate elevated overnight and reduce recovery, which shows up as a lower morning figure.
4. **A rollout in progress.** Zepp updates are phased by region, and the5krunner says features reach other models over a few weeks. If the score is missing, stuck or labelled differently on watch and phone, check the app and firmware version before concluding anything about your body.
5. **Heavy days.** Both gauges are built to fall during hard days. Ending the evening at 15 is the design working, not a fault.

If it stays low for weeks while you feel fine, compare it against your HRV and resting heart rate trend directly. Those two raw numbers are what both scores are mostly made of, and they don't change name between firmware updates. If your resting heart rate is persistently well above your normal range, or you have symptoms such as chest pain or dizziness, see a doctor and ignore the energy score.

## Can you compare the two numbers?

Not usefully. A 60 on Body Battery and a 60 on HybridCharge come from different models, different stated inputs and different baselines. Compare a gauge only against your own history on the same device. The same goes for a Garmin against an Oura or a WHOOP: the names sound alike, the scales differ and the methods are private.

If you wear a Fitbit Air or another device that syncs to Google Health, none of this applies directly. Pulse, a free app you host yourself, computes its own 0-100% [Energy Bank](/metrics/energy-bank/) from your Google Health data: a morning starting level from Recovery and Sleep Performance, then minute-by-minute drains for heart-rate load and stress and recharge for rest and naps. It's built and tested with the Fitbit Air only, and it does not read Amazfit or Garmin data. Its own page says it is an estimate with tuned constants and no published validation, which is the same honest caveat both vendors should carry.

Amazfit's other headline number works on a different timescale: [PAI, its weekly activity score](/blog/amazfit-pai-explained/), explained.

## Sources

1. [Garmin: Body Battery energy monitoring](https://garmin.ae/garmin-technologies/body-battery-energy-monitoring)
2. [the5krunner: Garmin Body Battery](https://the5krunner.com/garmin-features/sleep/body-battery/)
3. [the5krunner: Amazfit HybridCharge vs Garmin Body Battery and WHOOP (May 2026)](https://the5krunner.com/2026/05/25/amazfit-hybridcharge-garmin-whoop/)
4. [the5krunner: Amazfit April software updates (April 2026)](https://the5krunner.com/2026/04/22/amazfit-april-update/)
5. [Endurance.biz: Amazfit expands recovery insights with BioCharge](https://endurance.biz/2025/industry-news/amazfit-expands-recovery-insights-with-biocharge-energy-metric/)