EULUMDAT / IES Photometric Validator

Paste or drop an .ies (IESNA LM-63) or .ldt (EULUMDAT) file to confirm it parses cleanly and to read the key photometric values in plain language. This IES file validator is built for distributors and catalog teams who receive luminaire data from dozens of manufacturers and need to confirm a file is usable before it ever reaches a product record.

What it checks

The validator parses the file structure and reports both hard errors that break downstream tools and soft warnings that signal incomplete supplier data.

• Format and header — detects whether the file is IESNA LM-63 (.ies) or EULUMDAT (.ldt), and which LM-63 revision (for example the 1995 or 2002 keyword sets) the header declares.
• Required keywords — flags missing TILT data, manufacturer, luminaire description, or catalog/part number fields that catalogs frequently rely on.
• Photometric geometry — verifies that the declared number of vertical and horizontal angles matches the actual count of candela values, the most common cause of a corrupt or truncated file.
• Angle ranges — checks that vertical angles span a coherent range (for example 0–90 or 0–180 degrees) and that horizontal planes are consistent with the stated symmetry.
• Computed summary values — reads back total luminous flux (lumens), maximum candela and its angle, beam and field angles, and the number of lamps and watts so you can sanity-check a spec sheet against the file.
• Unit and multiplier sanity — confirms photometric units, luminous-opening dimensions, and the candela multiplier are present and numeric rather than blank or zero.

How it works

Photometric files describe how a luminaire distributes light. The North American standard is IESNA LM-63, a plain-text format with a keyword header followed by a fixed grid of candela values at defined vertical and horizontal angles. The European equivalent is EULUMDAT (.ldt), a line-delimited format carrying similar geometry plus lamp and luminaire metadata. Both encode the same physics in different layouts, which is why a file that opens fine in one lighting-design program can fail silently in another.

The tool tokenizes the file, separates the header from the candela block, and recomputes the expected value count from the declared angle dimensions. When the counts disagree — a frequent result of a copy-paste truncation or a bad export — it reports exactly where the grid breaks instead of failing with a generic error. It then surfaces the summary metrics a distributor actually publishes: flux, wattage, peak intensity, and beam spread.

Why this matters for an IES file validator in enrichment

For a distributor onboarding a lighting range, the photometric file is an enrichment input, not a finished attribute. Treating the parsed flux and beam angle as a candidate value with a known source mirrors how you would handle any spec pulled from a PDF or a supplier sheet — the same discipline you apply to an MRO fastener thread spec, a CPG net-weight field, or a furniture dimension. A validated file becomes a trustworthy source you can attach to the canonical record.

All parsing happens client-side in your browser. The file is never uploaded, so confidential manufacturer test data and pre-release SKUs stay on your machine. There is no login and no file-size limit.

Related resources

FAQ

What is an IES file? +

An IES file is a plain-text photometric data file in the IESNA LM-63 format. It describes how a light fixture distributes luminous intensity (candela) across a grid of vertical and horizontal angles, plus header metadata such as manufacturer, lamp count, and wattage. Lighting-design software uses it to simulate how a luminaire will light a space.

What is the difference between an IES and an LDT file? +

Both store the same kind of photometric data but in different layouts. IES (.ies) follows the North American IESNA LM-63 standard with a keyword header and a candela grid. LDT (.ldt) follows the European EULUMDAT format, which is line-delimited and carries additional lamp and luminaire fields. Many tools read one but not the other, so distributors often need to convert between them.

How do I know if my IES file is valid or corrupt? +

The most reliable check is whether the declared number of vertical and horizontal angles matches the actual count of candela values in the file. A mismatch — usually from a truncated export or a copy-paste error — is the leading cause of corruption. This validator recomputes that count and flags the exact point where the grid breaks, rather than failing with a vague error.

Is it safe to upload a manufacturer photometric file here? +

Nothing is uploaded. All parsing runs locally in your browser, so the file never leaves your computer. That keeps confidential test reports and pre-release product data private, with no login and no file-size limit.

Can I trust the lumens and beam angle the tool reports? +

The tool reads those values directly from the file and reports them faithfully, which lets you compare a file against a spec sheet. It cannot confirm the physical product matches — that requires the manufacturer test report. Treat the parsed values as a sourced candidate attribute, not a verified fact.