Scan QR Code from Screenshot Online (Instant Decoder)

How decoding from an image works

QR Code Format Variants and Decoder Compatibility

QR codes follow ISO/IEC 18004:2015, which defines four data encoding modes: numeric (up to 7,089 characters), alphanumeric (4,296 characters), byte (2,953 characters), and kanji (1,817 characters). Most screenshot decoders handle all four. Micro QR codes (variants M1–M4) carry far less data - M1 stores only 5 numeric digits - and many desktop tools fail silently on them. This decoder processes standard QR versions 1–40 and all four Micro QR variants. Structured Append mode splits a payload across up to 16 separate QR symbols; a partial screenshot containing only one segment will decode to a fragment, not an error - check the decoded string for truncation markers.

Error correction operates at four levels: L (7% recovery), M (15%), Q (25%), H (30%). A screenshot with up to 30% of the QR module area obscured or corrupted will still decode at level H. Below that threshold the Reed-Solomon algorithm reconstructs missing codewords without any visible indication that recovery occurred. High-contrast screenshots decode reliably at module sizes as small as 3×3 pixels per cell; below that, sub-pixel rendering artifacts cause finder pattern misreads.

Screenshot Quality Thresholds That Cause Decode Failures

JPEG compression introduces block artifacts at 8×8 pixel boundaries. QR modules smaller than 8 pixels wide collide with these boundaries and corrupt quiet-zone detection. Save screenshots as PNG before uploading; PNG is lossless and eliminates this failure mode entirely. Screen resolution matters: a QR code printed at 2.5 cm × 2.5 cm on a 96 DPI screen occupies roughly 94×94 pixels, which is marginal. The same code at 144 DPI (Retina) occupies 141×141 pixels and decodes first-pass consistently. Rotation up to ±45° is handled by the finder pattern orientation algorithm; beyond that angle, decoder accuracy drops below 80% on standard implementations.

Screenshots with overlaid UI elements - tooltips, notification banners, cursor artifacts - block modules. Even a 4-module overlap on a Version 5 code (37×37 modules, error level M) exceeds the 15% recovery budget. Crop the screenshot to the QR boundary before uploading. If the source app allows it, use the live QR code scanner with a direct camera feed to bypass screenshot degradation entirely.

What This Tool Does Not Do

This decoder reads the raw payload - it does not validate URLs against blocklists, expand shortened links, or resolve redirects. A QR code encoding bit.ly/xxxxxx returns that string; determining the destination requires a separate HTTP request the tool does not make. It does not parse vCard 3.0 or 4.0 fields into structured contact objects; the raw VCARD text block is returned as a single string. Calendar events encoded in iCalendar format (iCal, .ics) are returned verbatim - the tool does not parse DTSTART or RRULE fields. WiFi QR codes (WIFI:S:SSID;T:WPA;P:password;;) are decoded to plaintext, exposing the password in the output; treat that output as sensitive and clear it from browser history after use.