ZWO to FIT Converter

Understanding ZWO to FIT Conversion

Converting ZWO (Zwift Workout) files to FIT (Flexible and Interoperable Data Transfer) format allows you to use your structured Zwift workouts on Garmin devices and other fitness platforms. This conversion transforms Zwift's workout format into a device-compatible format that preserves all training structure and intensity targets.

What Data is Preserved?

The conversion process maintains all essential workout data, including:

• Workout intervals and structure
• Power targets converted from FTP percentages to absolute watts
• Interval durations and timing
• Workout metadata (name, description, author)
• Step types (SteadyState, Warmup, Cooldown, Intervals)
• Repeat instructions for interval sets

FTP-Based Power Conversion

ZWO files use relative power targets as percentages of your FTP (Functional Threshold Power). During conversion:

• Relative to Absolute: 90% FTP becomes your actual watts (e.g., 90% of 250W = 225W)
• Range Targets: Warmup and cooldown intervals with power ranges are preserved
• Default Values: Steps without power targets get sensible defaults based on interval type
• Precision: Power values are rounded to whole watts for device compatibility

FIT Format Benefits

The FIT format offers several advantages for workout files:

• Native compatibility with Garmin devices and Edge computers
• Support for structured workout steps and intervals
• Precise power targeting and duration control
• Integration with training platforms beyond Zwift
• Compact binary format for efficient storage

Workout Step Types

The converter handles all standard ZWO workout elements:

• SteadyState: Constant power intervals with fixed targets
• Warmup: Progressive intervals with power ramps (low to high)
• Cooldown: Recovery intervals with decreasing power targets
• Intervals: Repeated interval sets with specified repetitions

Common Use Cases

Converting ZWO files to FIT format is particularly useful for:

• Using Zwift workouts on Garmin Edge devices during outdoor rides
• Training with structured workouts on non-Zwift platforms
• Sharing workout files with coaches or training partners
• Creating workout libraries for different training devices
• Backing up and archiving structured training plans

Technical Details

The conversion process involves these steps:

1. Parsing the ZWO XML structure to extract workout elements
2. Converting relative power percentages to absolute watts using your FTP
3. Mapping ZWO step types to FIT workout step formats
4. Handling interval repetitions and nested workout structures
5. Creating FIT workout and workout step messages
6. Generating a properly formatted FIT file with workout metadata

Device Compatibility

The converted FIT workout files are compatible with:

• Garmin Edge cycling computers (Edge 520, 530, 830, 1030, etc.)
• Garmin fitness watches with workout support
• Training platforms that support FIT workout files
• Third-party fitness software with FIT import capabilities
• Coaching platforms and training analysis tools

Power Target Guidelines

For optimal conversion results:

• Accurate FTP: Ensure your FTP value reflects your current fitness level
• Realistic Targets: ZWO power targets should be achievable for your fitness
• Device Limits: Some devices may have maximum power limits (usually 1000W+)
• Step Duration: Very short intervals (<10 seconds) may not be practical on all devices

Best Practices

For optimal workout conversion and usage:

• Test converted workouts on your target device before important training sessions
• Keep original ZWO files as backups
• Update your FTP value regularly for accurate power targets
• Verify workout structure after conversion, especially for complex interval sets
• Consider device-specific power smoothing and response characteristics