Hardware Constraints
Yoto device specifications relevant to card making: cover dimensions, display pixels, audio pipeline, and label printing.
YotoShelf's audio, image, and label pipelines are shaped by Yoto hardware
constraints. Specifications are sourced from
yoto.dev/api/media,
yoto.dev/api/uploadCoverImage,
and yoto.dev/icons/dynamic-icons/.
See also
docs/hardware.md
in the repository.
Card physical dimensions
| Measurement | Value |
|---|---|
| Card size | 54 × 85.6 mm |
| Card thickness | ~1.2 mm |
| NFC chip | NTAG, centred |
| Material | PVC, credit-card form factor |
Cover image
The cover image is the digital artwork shown in the Yoto app and on yotoplay.com.
The Yoto API endpoint is POST /media/coverImage/user/me/upload.
YotoShelf uses coverType: default for all MYO cards.
Terminology note: Yoto calls this a "cover image". YotoShelf uses the same term. "Label" refers exclusively to the printable sticker output — a distinct concept.
| Property | Value |
|---|---|
| Dimensions | 638 × 1011 px (portrait) |
| Aspect ratio | 54 : 85.6 (~0.631) — portrait, not landscape |
| Format | JPEG or PNG |
| DPI equivalent | ~300 dpi at physical card size |
Cover types (from Yoto API)
| coverType | Width (px) | Height (px) | Aspect |
|---|---|---|---|
default | 638 | 1011 | Portrait |
activities | 638 | 1011 | Portrait |
music | 638 | 1011 | Portrait |
stories | 638 | 1011 | Portrait |
myo | 520 | 400 | Landscape (thumbnail) |
podcast | 600 | 600 | Square |
Track icons (LED display)
The Yoto Player has a front-facing LED matrix that displays a 16×16 icon during playback. The display is full-colour RGB — any colour except black can be shown. Avoid black pixels in icon content; they appear as unlit LEDs.
| Property | Value |
|---|---|
| Resolution | 16 × 16 pixels |
| Colour | Full RGB (32-bit RGBA) |
| Format | PNG; animated GIF also supported |
| Black (#000000) | Renders as "off" — not displayed |
| Compatibility | Player 3rd gen, Mini 2024 |
The palette system in YotoShelf is an aesthetic constraint, not a hardware limitation. Any RGB colour can be displayed.
Device types
| deviceType | deviceFamily | formFactor | Description |
|---|---|---|---|
minie | mini | mini | Yoto Mini |
v3e | v3 | standard | Yoto Player v3 |
The formFactor field is useful for UI layout decisions
(the Mini has a smaller display than the standard Player).
All currently-tested devices report generation: "gen3".
Audio pipeline
Yoto re-encodes all uploaded audio server-side, regardless of source format or bitrate. There is no way to bypass this step.
| Property | Value |
|---|---|
| Container | MP4 (M4A) |
| Codec | AAC (libfdk_aac) |
| Bitrate | 128 Kbps |
| Sample rates | 11025 / 22050 / 44100 / 48000 Hz |
| Channels | Pass-through (mono/stereo preserved) |
| Max upload size | 1 GB |
Recommended upload strategy
- Upload the highest-quality source available. Yoto re-encodes everything, so lossless (FLAC/WAV) input gives the best final result — one lossy step instead of two for an MP3 source.
- YotoShelf transcodes to AAC 128 Kbps 44.1 kHz locally for preview playback; the original is uploaded to Yoto when publishing.
- Keep originals on the library volume — they are used for re-publish if needed.
Label printing
YotoShelf generates printable sticker labels for blank NFC cards (the label, distinct from the digital cover image). Community-recommended templates:
| Template | Cell size | Cards/sheet | Notes |
|---|---|---|---|
| Full sheet 9-up (US Letter) | 54 × 85.6 mm | 9 | Most popular. Glossy printable vinyl, cut to size. |
| Full sheet 9-up (A4) | 54 × 85.6 mm | 9 | International equivalent. |
| Avery Presta 94237 | 2" × 3" (51 × 76 mm) | 8 | Pre-cut waterproof film. Slightly smaller — thin border visible. |
| Avery L7414 | 85 × 54 mm | 10 | UK/EU pre-cut. Exact Yoto card size. |
Glossy printable vinyl with a clear contact paper overlay produces results indistinguishable from official Yoto cards. Matte paper and business card stock are not recommended — the material does not hold up to regular child handling.