Convert Garmin to ZWO

Take a Garmin Connect workout (GCN JSON) into a Zwift ZWO file so a plan from Garmin can run in Zwift. Use the free, in-browser Kaiord Editor (no account, no upload), or the CLI and TypeScript SDK. Conversions go through Kaiord's canonical KRD format and stay within round-trip tolerances (time ±1 s, power ±1 W or ±1 % FTP).

Three ways to convert

1. Editor (drag & drop)

Open kaiord.com/editor, drop your Garmin Connect workout file, choose ZWO as the export format, and download workout.zwo.

2. CLI

pnpm add -g @kaiord/cli
kaiord convert -i workout.gcn -o workout.zwo

3. SDK

import { fromText, toText } from "@kaiord/core";
import { garminReader } from "@kaiord/garmin";
import { zwiftWriter } from "@kaiord/zwo";
import { readFile, writeFile } from "node:fs/promises";

const gcn = await readFile("workout.gcn", "utf-8");
const krd = await fromText(gcn, garminReader);
const zwo = await toText(krd, zwiftWriter);
await writeFile("workout.zwo", zwo);

What survives the conversion

Data	Garmin Connect (GCN)	ZWO (Zwift)	Result
Step order & names	workout steps	blocks (names as kaiord:name)	Preserved
Time durations	time durations	Duration seconds	Preserved (±1 s)
Distance durations	distance durations	time-based Duration	Converted to time; original kept under extensions.zwift
Power targets	watts	% FTP (Power fraction)	Converted using an assumed FTP (see below)
Repeats / intervals	repeat blocks	IntervalsT	Preserved
Steps without power	open / non-power target	FreeRide	Rendered as a free-ride segment
Heart-rate targets	bpm	—	Dropped (Zwift is power-based); kept under extensions.zwift

Gotchas

Watts vs. % FTP. Garmin Connect stores power as watts; Zwift needs % FTP. The conversion divides watts by an assumed FTP (recorded as kaiord:assumedFtp, e.g. 250 W). If the percentages look off, rescale to your own FTP.

Non-power steps become free rides. ZWO is power-centric. Garmin steps that target heart rate or have no power target become FreeRide segments, since Zwift has no equivalent structured target for them.

Where do I get the .gcn file? GCN is Garmin Connect's workout JSON. Fetch it through the Garmin Connect API with @kaiord/garmin-connect (e.g. kaiord garmin list) or the Editor's Garmin integration.

Related

• Convert ZWO to Garmin — the reverse direction
• Convert FIT to ZWO — a device-file source
• GCN format · ZWO format
• All converters