ISO 6346 check digit calculator.
Paste an 11-character container number and get an instant valid or invalid verdict, plus the owner code, category, serial, and check digit broken out. Runs entirely in your browser. No signup, no upload, no logs.
How is the ISO 6346 check digit calculated?
Each of the first 10 characters gets a value (letters map A=10 through Z=38, skipping multiples of 11), each value is multiplied by a power of 2 by position, the products are summed, and the sum modulo 11 gives the check digit, with a result of 10 written as 0. A container number that fails this test is not a valid ISO 6346 number, no matter how clean the scan looked.
What Vantage YMS does, from a phone.
Gate operations, C-TPAT inspection, live yard map, carrier appointments, driver-license capture, yard moves and analytics — and photo number reading in the iPhone app, with container numbers checked against this same check digit.
How the app reads a container number
Photo, not typing.
A clerk photographs the number from a phone. Works offline in the iPhone app, no kiosks, no fixed cameras at the gate.
Checked before it lands.
Container reads are checked against the ISO 6346 check digit and single-character misreads are auto-corrected; the clerk confirms every read before it is saved.
Fewer typos in the gate log.
The clerk checks each read at the gate, not three hours later in the yard.
…and a full yard management system
Gate IN / OUT.
End-to-end gate transactions — container, trailer, driver, seal, and appointment all linked at the moment of scan.
C-TPAT 7-point inspection.
Digital 7-point checklist with photo audit pack, timestamp, an optional driver signature, and SHA-256 hash of each photo for audit support. In the iPhone app, on Pro and above.
Live yard map.
Real-time slot view. Manager sees every door, every move from any browser.
Carrier appointments.
Your team books and tracks carrier appointments from the browser.
Driver license scan.
PDF417 + AAMVA parser auto-fills name, DOB, expiration, class for US / CA licenses. No re-keying. Photo retained for incident review.
Move log.
Trailer moves are logged by site with a timestamp.
Analytics & KPIs.
Throughput, detention exposure, gate dwell, inspection pass-rate, OCR accuracy — the dashboards a full YMS gives you, included in the plan price.
14-day offline queue.
Walk into a dead zone, finish the cycle, sync on reconnect. The gate keeps recording offline (up to 500 queued moves, 14 days) and syncs when the signal returns.
No fixed gate hardware.
The phone replaces kiosks, RFID, scanner guns, and camera towers. Designed to go live without an install project.
Bilingual ready.
EN · ES · KO · ZH at login. US 3PLs with Spanish-speaking gate staff get an immediate first-day fit.
Published, $149+/mo.
No sales call required — but we're happy to hop on one. No five-figure annual contract. Lite $149, Pro $349 with C-TPAT inspection, Scale $649. Paid plans start with a 14-day trial (card required, no charge until day 15), no setup fee, cancel anytime. Or start free with no card; the Free plan never expires.
Multi-site, multi-tenant.
One organization, multiple yards. Site-scoped permissions, per-site KPIs, and Row Level Security on every query.
Frequently asked
Does this tool send my container number anywhere?
No. The calculator runs entirely in your browser. Nothing is uploaded, logged, or stored — you can disconnect your network and it will still work.
A valid check digit means the container is real, right?
Not necessarily. A valid check digit confirms the number is internally consistent, not that it belongs to a real, registered container. Vantage YMS pairs this with your appointment data so a valid-but-unexpected container gets flagged at the gate, not after the fact.
Does this work for trailer numbers and US domestic intermodal?
This calculator covers ISO 6346 sea/ocean containers only. Vantage YMS itself reads container numbers, trailer numbers, license plates, and chassis numbers — but that's a job for the app, not this tool.
The other free tools
Put this calculator on your own site
Free to embed on any site, no permission or attribution needed beyond the small credit line inside the widget. It loads a stripped-down view with no header, no footer, and no marketing.
Skip the math. Let the phone do it.
Vantage YMS — free plan, no card. Cancel anytime.