PDF417

PDF417 is the stacked-linear 2D barcode that appears on the back of every US driver license, on most US passports, on FedEx/UPS airbills, and on countless government forms. It's the only 2D symbology that can be read reliably by 1D laser scanners — which is why institutions with million-dollar installed scanner bases haven't moved off it in 30 years.

Canonical spec: ISO/IEC 15438:2015 — Information technology — Automatic identification and data capture techniques — PDF417 bar code symbology specification.
AAMVA application: AAMVA Card Design Standard v10 — mandates PDF417 for US/Canadian driver licenses.
Originator: Symbol Technologies (now Zebra), 1991. Name stands for "Portable Data File, 4 bars, 17 modules."

What it is

Physically, a PDF417 symbol is a stack of horizontal rows — each row is a linear barcode. A full-size PDF417 looks like a tall narrow brick with ~3–90 rows, where each row carries a slice of the overall payload. Because every row starts with a start pattern and ends with a stop pattern, PDF417 can be decoded by a scanning laser sweeping left-to-right row by row — no 2D imager required.

Each codeword is 17 modules wide, built from 4 bars and 4 spaces (hence "4/17"). The payload is split across codewords using one of three "compaction modes":

Text Compaction — 1.8 chars/codeword. Used for mixed alphanumerics.
Byte Compaction — 1.2 bytes/codeword. Used for arbitrary binary.
Numeric Compaction — 2.9 digits/codeword. Used for long numeric payloads (like AAMVA's zip+state combinations).

Capacity (rows × columns)

PDF417 size is specified as rows × data columns. Max is 90 rows × 30 data columns = 2,700 data codewords. Approximate alphanumeric capacity:

Rows × data cols	Max alphanumeric	Typical use
3 × 1	~3 chars	Minimum viable symbol
10 × 3	~30 chars	Short IDs, short URLs
20 × 5	~100 chars	Boarding pass, short AAMVA
30 × 8	~250 chars	FedEx airbill
40 × 12	~500 chars	Full AAMVA driver license
90 × 30	~1,800 chars	Theoretical max — rarely used

Error correction levels (0–8)

PDF417 defines 9 levels of Reed-Solomon error correction, adding 2, 4, 8, 16, 32, 64, 128, 256, or 512 codewords of ECC. Higher levels handle more damage but cost payload capacity.

ECC level	ECC codewords	Typical use	% overhead
0	2	Experimental only	~0.1%
1	4	Short codes, controlled environment	~0.2%
2	8	Small payloads	~0.4%
3	16	Medium payloads, indoor scanning	~0.8%
4	32	Default for short documents	~1.5%
5	64	Real-world default — airbills, boarding passes, AAMVA	~3%
6	128	High-damage environments	~6%
7	256	Crumpled / outdoor / industrial	~12%
8	512	Extreme environments	~25%

Macro PDF417 (multi-symbol payloads)

When a payload exceeds the 1,800-char cap, PDF417 supports Macro PDF417 — the payload is split across up to 99,999 separate symbols, each tagged with a Macro index and File ID. The scanner reads all symbols in any order, reassembles, and emits a single decoded payload. Rare in practice outside specialist document scanning.

Canonical test vectors

Case	Payload	Expected substring
GS1 airbill (FedEx-style)	`123456789012345 FEDEX 2026-04-20`	`FEDEX`
AAMVA driver license (minimal)	`@\n\x1e\rANSI 636014100002DL00410241ZVZVA01DAQA123456789`	`ANSI 636014`
Short plain URL	`https://example.com/doc/X1234`	`example.com/doc/X1234`
Long receipt / invoice	`INV:2026-04-19 VENDOR:ACME TOTAL:$1,234.56 TAX:$98.76 …`	`ACME`

Common pitfalls

Consumer phone cameras don't decode PDF417 reliably. iOS 17+ has a special AAMVA-aware flow (Wallet recognises US driver licenses), but treating that as "iPhone supports PDF417" is misleading — it's only for the specific AAMVA payload. Android behaviour varies wildly by OEM camera app.
AAMVA mandates PDF417. The AAMVA Card Design Standard (CDS) requires PDF417 specifically — not QR, not Aztec. If you're generating AAMVA payloads, the standard locks you in.
Quiet zones are 2× module width. Different from QR (4 modules) and Aztec (none). PDF417 needs at least 2 modules of white space on the left and right edges; getting the quiet zone wrong is the #1 reason legitimate PDF417 codes fail at scan time.
Aspect ratio matters. PDF417 rows are wider than tall by design. Forcing a square aspect ratio (by scaling or by printing on a square substrate) breaks laser-scanner decoding; 2D imagers can sometimes recover.
Truncated PDF417. Variant that omits the right row indicator + stop pattern. Saves ~12% symbol width but only decodes on 2D imagers — laser scanners need the stop pattern. Use only when you know the scanner class.
Compaction mode auto-selection. Good encoders switch compaction mid-payload for efficiency (numeric block → text block). Manual encoders that lock a single mode waste capacity. Abundera's encoder auto-selects per codeword.
Compaction mode and character set. Text Compaction handles printable ASCII only. Embedded NULs, Latin-1 accents, or binary data force Byte Compaction, which drops efficiency to 1.2 bytes/codeword.
Styling disabled. QR-specific features (custom dot shapes, gradients, centre logos) don't apply. Abundera's Style panel disables itself for PDF417.

Scanner compatibility

Reader	PDF417 support	Notes
iOS Camera (iOS 17+)	AAMVA-only	Native Wallet flow for US driver licenses. General PDF417 payloads don't decode.
Android Camera (OEM-dependent)	Partial	Samsung + Pixel stock cameras decode inconsistently. Google Lens partial.
Google Lens	Unreliable	Not a viable verification path for production.
US DMV / kiosk scanner	Yes (canonical)	This is what PDF417 was designed for — every DMV and liquor kiosk reads PDF417 natively.
Airline boarding-pass reader	Some carriers	Most airlines moved to Aztec; a few (ANA, JAL, legacy US carriers) still accept PDF417 boarding passes.
FedEx / UPS airbill reader	Yes (canonical)	Laser scanners at every sorting facility read PDF417 natively.
1D laser scanner	Yes	Unique advantage vs Aztec / Data Matrix — 1D lasers CAN decode PDF417.
Zebra / Honeywell / Datalogic imager	Yes	Every industrial 2D imager supports PDF417.
Scandit / Dynamsoft SDK	Yes	Full support including Macro PDF417.