---
url: /docs/convert.md
description: >-
  Free, in-browser converter for FIT, TCX, ZWO, and Garmin Connect workout
  files. No account, no upload. Plus a CLI and TypeScript SDK for developers.
---

# Workout file converter — FIT, TCX, ZWO & Garmin

::: info Scope
Converts structured workouts (steps and targets), not recorded activities.
See [Workouts vs. activities](#workouts-vs-activities).
:::

Convert workout files between **FIT**, **TCX**, **ZWO** (Zwift), and **Garmin
Connect** formats — free, in your browser, with no account and no file upload.
Choose a file in the [Kaiord Editor](https://kaiord.com/app/#/convert) and download
the result. Developers can script the same conversions with the
[CLI](/cli/commands) or the [TypeScript SDK](/guide/quick-start).

Every conversion goes through **KRD**, Kaiord's canonical format, so round-trips
stay within tight tolerances (time ±1 s, power ±1 W or ±1 % FTP, heart rate
±1 bpm, cadence ±1 rpm). See the [KRD format](/formats/krd) for the details.

## Pick a conversion

| From ↓ / To → | FIT                                    | TCX                                    | ZWO (Zwift)                            | Garmin                                 |
| ------------- | -------------------------------------- | -------------------------------------- | -------------------------------------- | -------------------------------------- |
| **FIT**       | —                                      | [FIT → TCX](/convert/fit-to-tcx)       | [FIT → ZWO](/convert/fit-to-zwo)       | [FIT → Garmin](/convert/fit-to-garmin) |
| **TCX**       | [TCX → FIT](/convert/tcx-to-fit)       | —                                      | [TCX → ZWO](/convert/tcx-to-zwo)       | [TCX → Garmin](/convert/tcx-to-garmin) |
| **ZWO**       | [ZWO → FIT](/convert/zwo-to-fit)       | [ZWO → TCX](/convert/zwo-to-tcx)       | —                                      | [ZWO → Garmin](/convert/zwo-to-garmin) |
| **Garmin**    | [Garmin → FIT](/convert/garmin-to-fit) | [Garmin → TCX](/convert/garmin-to-tcx) | [Garmin → ZWO](/convert/garmin-to-zwo) | —                                      |

All twelve directed pairs have a guided walkthrough. Every conversion uses the
same [`kaiord convert`](/cli/commands#convert) command and SDK calls — the
format is detected from the file extension.

## Three ways to convert

1. **Editor** — [kaiord.com/app](https://kaiord.com/app/#/convert). Choose a
   file, pick the target format, download. Nothing leaves your browser.
2. **CLI** — `kaiord convert -i workout.fit -o workout.zwo`. Formats are
   detected from the extensions. See the [CLI reference](/cli/commands#convert).
3. **SDK** — `@kaiord/core` plus the reader/writer for each format. See the
   [Quick Start](/guide/quick-start).

## Workouts vs. activities

A **workout** is the plan: an ordered list of steps, each with a duration
(time, distance, open…) and a target (power, heart rate, pace, cadence). It is
what you load on a watch or head unit before a session. An **activity** is the
recording of a session you already did: the samples, laps and totals your
device logged.

These converters move **workouts** between formats. FIT and TCX can also hold
activities, and the Kaiord app can import a recorded activity onto your
calendar, but these pages do not turn a recorded ride or run into a workout,
and a converted file carries no recorded data.

## What is lossless?

KRD is designed to be round-trip safe, but the source and target formats are
not identical — each pair page has a **"What survives the conversion"** table
and the gotchas that matter for that direction. In short:

* **FIT** is the richest workout format (power, heart rate, cadence, speed, and
  distance/time durations).
* **TCX** workout targets are heart rate, speed, and cadence — **not power**.
* **ZWO** is power-based (% of FTP); heart-rate and cadence targets have no
  native equivalent.
* **Garmin Connect (GCN)** covers power, heart rate, speed, and cadence in
  watts/bpm/rpm, plus calorie durations. Power targets in % FTP (every ZWO
  target, ramps included, and FIT targets stored as % FTP) are converted to
  watts with your FTP; without one the conversion stops instead of guessing.

Format-specific data that has no target-side equivalent is preserved under the
KRD `extensions` object so it can survive a later round-trip.

## Formats

* [FIT](/formats/fit) — Garmin's binary protocol
* [TCX](/formats/tcx) — Training Center XML
* [ZWO](/formats/zwo) — Zwift workout XML
* [GCN](/formats/gcn) — Garmin Connect JSON
* [KRD](/formats/krd) — Kaiord's canonical format