HEIF to SIX Converter

Convert HEIF images to SIX format online — fast and free

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Private & Secure

Your uploaded HEIF files are erased immediately after conversion, and the resulting SIX is removed from servers within 24 hours — keeping your data private.

Works Everywhere

No app downloads needed. The browser-based tool converts HEIF to SIX on Windows, Mac, Linux, iOS, and Android devices seamlessly.

Speed Matters

Get your SIX output fast — HEIF conversion typically finishes within moments, powered by optimized server infrastructure.

How to convert HEIF to SIX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose six or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your six file right afterwards

About formats

HEIF (High Efficiency Image File Format) is a container format for images and image sequences standardized by the Moving Picture Experts Group as ISO/IEC 23008-12, first published in 2015. HEIF is built on the ISO Base Media File Format (ISOBMFF, the same container used for MP4 video), providing a flexible structure that can hold single images, image collections, image sequences (like animations or bursts), and derived images with non-destructive editing operations. The container is codec-agnostic — while the most common implementation pairs HEIF with HEVC/H.265 compression (branded as HEIC by Apple), the standard also accommodates AV1 compression (creating the AVIF variant), H.266/VVC, and other future codecs. HEIF supports features that JPEG lacks: 10-bit and 12-bit color depth, wide color gamuts (Display P3, BT.2020), lossless compression, alpha transparency, depth maps, thumbnail images, and Exif/XMP metadata — all within a single file. Auxiliary image items can store computational photography data like depth maps, HDR gain maps, and semantic segmentation masks. One advantage is the format's future-proof architecture: by separating the container from the codec, HEIF can adopt newer, more efficient compression technologies without changing the file structure, metadata handling, or application-level APIs. The substantial compression improvement over JPEG is another core strength — HEVC-based HEIF typically achieves 40-50% file size reduction compared to JPEG at the same visual quality, beneficial for storage and bandwidth. HEIF is supported by Apple's ecosystem (iOS, macOS), Windows 10/11, Android 10+, GIMP, ImageMagick, and Adobe products.
Initial release: 2015
SIX is a file extension for SIXEL (Six Pixel) graphics data, a bitmap graphics format developed by Digital Equipment Corporation (DEC) in 1983 and introduced with the LA50 dot matrix printer. SIXEL encodes images as a sequence of printable ASCII characters, where each character represents a column of six vertical pixels (a 'sixel') — the character's ASCII value minus 63 provides a 6-bit binary pattern, with each bit controlling one pixel in the vertical column. The encoding is structured as a series of sixel bands (each six pixels tall) across the image width, with control sequences for color selection (up to 256 registers with HLS or RGB specification), repeat counts (run-length encoding for efficiency), carriage return, and newline commands. SIXEL data is transmitted to the output device using DEC's standard escape sequence protocol, embedded within the text stream alongside regular character output. Originally designed for DEC's line of printers and later supported by DEC VT-series terminals (VT240, VT330, VT340), SIXEL has experienced a remarkable revival in modern terminal emulator software. One advantage is terminal-native image display: SIXEL allows images to be rendered directly within a text terminal session without requiring a graphical window system, enabling command-line tools to display graphs, photographs, and previews inline with text output. This capability has driven adoption in modern terminals like mlterm, xterm, WezTerm, and foot. SIX/SIXEL data can be generated by ImageMagick, libsixel, and chafa, and viewed in any SIXEL-capable terminal emulator.
Initial release: 1983

Frequently Asked Questions

Why convert HEIF to SIX?

HEIF offers superior compression but many platforms still can't open it — converting to SIX ensures your images display correctly everywhere.

What software can open SIX?

SIX works with compatible terminal emulators like mlterm, xterm, and mintty.

How long are converted files stored?

Convertio keeps converted files for up to 24 hours. You can download your SIX anytime within that window — files are purged after.

How fast is the HEIF to SIX conversion?

Speed depends on file size, but most HEIF to SIX conversions complete in under a minute. Server-side processing ensures quick turnaround.

Can I convert multiple HEIF files to SIX at once?

Yes — upload several HEIF images at the same time and they will all be converted to SIX in a single batch for convenient download.

Is my HEIF file safe during conversion?

Your files are handled securely. The HEIF upload is erased right after processing, and the resulting SIX is purged from servers within 24 hours.