Sync Weight from Any Smart Scale to Garmin Connect & Intervals.icu

2026-04-01 · liming

The short answer: Garmin Connect only accepts weight data from Garmin's own Index smart scales. If you use a Withings, Fitbit, Xiaomi, or Huawei scale, your weight data is locked out. GarSync bridges this gap by reading weight from Apple Health (where virtually all smart scales write to) and syncing it to Garmin Connect and Intervals.icu — keeping your W/kg calculations accurate.

Why Your Smart Scale Can't Talk to Garmin Connect

Garmin Connect has a hard gate on weight data: it only accepts input from Garmin's own devices.

Garmin Index S2 / Index BPM → auto-syncs ✅
Withings, Fitbit Aria, Xiaomi, Huawei, any third-party scale → blocked ❌

This isn't a technical limitation — it's a business decision. Garmin wants you in their ecosystem. But an Index S2 costs $149.99, and if you already own a perfectly good smart scale, buying another one is wasteful.

Weight Data Isn't Just "Nice to Have" — It Directly Affects Key Training Metrics

Power-to-weight (W/kg): The single most important metric in cycling. A 1 kg difference shifts your FTP from 3.5 to 3.4 W/kg — that's a different rider category.
VO2max: Garmin's VO2max formula includes body weight. Stale weight = inaccurate trend.
Calorie burn: Every platform's calorie estimates depend on weight.
Intervals.icu Fitness chart: Weight is the W/kg denominator. Missing data creates gaps in your power-to-weight curve.

GarSync's Weight Sync Flow

iOS: Apple Health as the Hub

Nearly every smart scale writes to Apple Health (built into each scale's companion app). Add Apple Health as a data source in GarSync, create a sync task to Garmin or Intervals.icu. After each weigh-in, open GarSync and tap sync once — weight data pushes to all targets.

Android: Direct Bind Xiaomi Health

Add Xiaomi Health directly as a data source in GarSync. If you use a Xiaomi smart scale, GarSync reads your weight data directly — no intermediate platform, one-tap sync to Garmin and Intervals.icu.

3 Steps to Set Up Auto Weight Sync

Step 1: Verify Your Scale Writes to Apple Health

Open the Health app on iPhone → Browse → Body Weight. If you see historical entries, your scale is already writing there. Most companion apps (Huawei Health, Mi Fitness, Withings, Fitbit) enable this by default.

Step 2: Add the Data Source in GarSync

In GarSync's Account Management, iOS users add Apple Health, Android users add Xiaomi Health as a data source.

Step 3: Create the Sync Task

Create a task: Source = Apple Health or Xiaomi Health → Target = Garmin or Intervals.icu → data type = Weight. Enable auto-sync, and every weigh-in auto-propagates.

FAQ

Q: Will synced weight data show up in the Garmin Connect app?

A: Yes. It appears as standard weight entries under Health Stats → Weight, identical to data from a Garmin Index scale.

Q: Does it sync body fat %, BMI, and other metrics too?

A: GarSync currently syncs only weight data to Garmin and Intervals.icu. Weight is the direct input for key training metrics like W/kg and VO2max — and it's the most important data point.

Q: Can I sync historical weight data?

A: GarSync syncs weight data from the recent 2 weeks. The purpose is to keep Garmin and Intervals.icu metrics like W/kg based on your latest weight — not to serve as a long-term archive.

Q: How is this different from manually entering weight in Garmin Connect?

A: Manual entry means opening Garmin Connect, navigating to Health Stats, finding Weight, and typing in numbers — too many steps, easy to skip. GarSync is one-tap sync: step on the scale, open the app, tap once, and your weight is pushed to Garmin and Intervals.icu.