MKV to HEIF Converter

Extract an MKV Frame as HEIF

Grab a single still from an MKV (Matroska) video — or a series of stills — and save it as HEIF, the space-efficient HEVC-coded still format. You pick the exact moment by timestamp, and each frame comes out as its own .heif image that's roughly half the size of the equivalent JPEG. This pulls frames, not the whole clip: the output is one image per frame, not a playable video. HEIF is the most compact option here, but it doesn't open everywhere — if you need a still that works on any device, MKV to JPG is the safer pick.

How to Convert MKV to HEIF

1. Upload Your MKV File: Drag and drop or click "+ Add Files" to select one or more .mkv videos. Batch is supported, so several clips can be queued in one pass.
2. Pick Frame Selection: Choose Specific Frame and enter the moment in Time (seconds) — e.g. 8.5 for the 8.5-second mark, or 2.100 for 2 seconds and 100 milliseconds — to get one still. Or choose Multiple Screenshots to extract a sequence; the separate stills come back together as a ZIP.
3. Set Quality Preset (Optional): Quality Preset defaults to Very High (Recommended). Pick Highest for the cleanest still, or step down to Medium / Low for smaller files. Under Image resolution you can keep original, scale by percentage, or set an exact Width x Height.
4. Convert and Download: Click Convert. Each selected frame becomes its own .heif image. No sign-up, no watermark.

HEIF vs JPG vs PNG for an Extracted Frame

If you need a still that opens anywhere without fuss, MKV to JPG is the universal pick; MKV to PNG gives you a lossless-style frame for editing. Reach for HEIF when the destination is an Apple photo library and disk space matters.

Frequently Asked Questions

Will the extracted HEIF open on Windows or Android?

Not always without help. HEIF decodes out of the box on iOS 11+, iPadOS, and macOS High Sierra (10.13) or later, the releases where Apple adopted it as a still-image format (Apple Support). Windows 10 and 11 show a "You need an extension to use this file" prompt in the Photos app until you install the free HEIF Image Extensions from the Microsoft Store (Microsoft Support), and many Android gallery apps still re-encode to JPEG on share. In browsers, only Safari 17+ renders HEIF natively — Chrome, Firefox, and Edge have no native decoder (caniuse.com/heif). If the image has to open everywhere, extract the frame as MKV to JPG instead, or run a HEIF through HEIF to JPG afterward.

How sharp can the extracted frame be?

The frame can only be as sharp as the source video. MKV is just a Matroska container (introduced in 2002) — it doesn't define the picture quality, the codec and footage inside it do. A still pulled from a 4K HEVC clip will be crisp; one pulled from an upscaled or heavily compressed stream inherits that stream's softness and any motion blur on the chosen frame. Re-encoding to HEVC won't invent detail that isn't there, so keeping Image resolution on Keep original and Quality Preset on Highest preserves the most the source frame can offer.

How much smaller is a HEIF still than the same frame as JPEG?

HEIF is built on HEVC, whose intra-frame prediction is far more efficient than JPEG's 8×8 DCT blocks, so it stores the same picture in noticeably less space. The format itself is standardized as ISO/IEC 23008-12 (MPEG-H Part 12). Independent comparisons usually put a HEIF still at roughly 40–60% of the JPEG file size at matched visual quality, with the gap widening on detail-heavy frames. Apple makes the same general claim — smaller files at equal quality — without publishing a fixed percentage.

Can I pull several frames at once from one MKV?

Yes. Choose Multiple Screenshots and set a capture rate — the default grabs one frame per second of footage, and you can go denser or sparser. Each captured moment becomes a separate HEIF, and the set is delivered as a ZIP. In our testing, a 10-second MKV captured at one frame per second produced 10 individual .heif stills in a single download. If you want a smooth animation rather than separate stills, convert the clip with MKV to GIF instead.

How are my uploaded files handled, and is the original MKV changed?

Your MKV is uploaded over an encrypted connection, the requested frames are read from a copy on our servers, and new HEIF files are written from them. Files are deleted automatically a few hours after conversion — never shared or made public, no sign-up required. Your original .mkv on your device is never modified.