FIT to ERG Converter
Convert power-based FIT files to ERG format for structured indoor training
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All file conversions happen directly in your browser. We never upload, store, or save your files on any server. Your data remains completely private and secure.
How to Convert FIT to ERG
Follow these simple steps to convert your files quickly and easily
Upload Your FIT File
Click the upload area above or drag and drop your FIT file. Only power-based FIT files from power meters or smart trainers can be converted to ERG format.
Choose Power Mode & Convert
Select absolute power (watts) or percentage of FTP mode. If using FTP percentages, enter your FTP value, then click convert to create your structured workout.
Download Your ERG File
Once conversion is complete, download your new ERG file. Import it into TrainerRoad, Zwift, or other training software for structured indoor sessions.
About FIT to ERG Conversion
Learn more about the converter and its creator
Jonas
I'm a software developer and sports enthusiast. I created these converters to help athletes manage their workout data efficiently.
Understanding FIT to ERG Conversion
Converting FIT (Flexible and Interoperable Data Transfer) files to ERG format allows you to transform your recorded power-based workouts into structured training files that can be used with indoor training applications like TrainerRoad, Zwift, Wahoo SYSTM, and other smart trainer software. ERG files define power targets over time for structured interval training.
What Data is Required?
For successful FIT to ERG conversion, your file must contain:
- Power data - Recorded from a power meter or smart trainer
- Timestamp information - To determine workout duration and timing
- Consistent power readings - For accurate interval detection
Power Output Modes
The converter offers two power output modes:
- Absolute Power (Watts) - Uses exact power values from your workout, ideal for replicating the exact intensity
- Percentage of FTP - Converts power to relative zones based on your Functional Threshold Power, perfect for scalable training
ERG File Format Benefits
The ERG format offers several advantages for structured training:
- Compatible with most indoor training applications
- Defines precise power targets for interval training
- Supports both absolute watts and FTP percentage modes
- Lightweight text format that's easy to edit and share
- Perfect for creating custom workouts from real-world efforts
- Enables repeatable and progressive training sessions
Common Use Cases
Converting FIT files to ERG format is particularly useful for:
- Recreating outdoor interval sessions indoors
- Sharing custom workouts with training partners or coaches
- Converting race efforts into training sessions
- Creating structured workouts from unstructured rides
- Building a library of power-based training sessions
- Analyzing and replicating successful training sessions
- Creating FTP-relative workouts for different fitness levels
Workout Segmentation Process
The conversion process intelligently analyzes your power data:
- Power Smoothing - Applies moving average to reduce noise and spikes
- Segment Detection - Identifies distinct power intervals based on intensity changes
- Duration Filtering - Ensures minimum segment lengths for meaningful intervals
- Threshold Analysis - Detects significant power changes to create new segments
- FTP Conversion - Converts absolute power to percentage zones when selected
Technical Details
The conversion process involves these steps:
- Reading and validating the FIT file for power data
- Extracting power records with timestamp information
- Applying smoothing algorithms to reduce power data noise
- Analyzing power patterns to identify distinct intervals
- Creating workout segments with start time, duration, and target power
- Converting to ERG file format with proper headers and structure
- Formatting for compatibility with major training platforms
ERG File Structure
The generated ERG file includes:
- Course Header - Metadata about the workout and power units
- Course Data - Time and power target pairs defining the workout structure
- Time Format - Minutes from start for easy reading and editing
- Power Format - Either absolute watts or FTP percentages
Pro Tip
For best results, use FIT files from structured workouts or interval sessions. The converter works by detecting power changes, so workouts with distinct intensity levels will produce better ERG files than steady-state rides. Consider using the FTP percentage mode to create scalable workouts that can be adjusted as your fitness improves.
Training Application Compatibility
The generated ERG files are compatible with popular training applications including TrainerRoad, Zwift, Wahoo SYSTM, Rouvy, and most other smart trainer software. The standard ERG format ensures your converted workouts will work across different platforms and devices.
Power Data Requirements
This converter only works with FIT files that contain power data from power meters or smart trainers. Files from GPS-only devices, heart rate monitors, or activities without power recording cannot be converted to ERG format. Ensure your device was recording power data during the activity.