IlluminanceLux to Phot

Lux to Phot

Snapshot

1 Lux equals 0.0001 Phot. Conversion Encyclopedia uses the same fixed conversion basis across the calculator, common values, and reverse page for this page.

Reference basis: This conversion uses exact lux-based illuminance definitions.
Example: For 10 Lux, the result equals 0.001 Phot.
Use the reverse page if you need the opposite direction with the same basis.

Use the interactive calculator below for custom values and the common-value table for quick checks.

Interactive conversion

Converter Calculator

0.0001 Phot (ph)

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Machine access

Available to apps and AI agents

Lux to Phot can be requested through Conversion Encyclopedia's structured interfaces by software and compatible AI agents. The identifiers below select the same calculation as the calculator.

Machine-readable identifiers

Conversion family: illuminance
Source unit: lux
Target unit: phot

The JSON API and OpenAPI specification use the identifiers to reach the conversion engine. WebMCP lets compatible AI agents request the same calculation.

Example API request and response

POST /api/v1/convert

Request

{
  "family": "illuminance",
  "value": 1,
  "from": "lux",
  "to": "phot"
}

Essential response

{
  "ok": true,
  "conversion": {
    "family": "illuminance",
    "value": 1,
    "from": "lux",
    "to": "phot",
    "result": {
      "raw": 0.0001,
      "display": "0.0001"
    },
    "canonicalPath": "/illuminance/lux-to-phot/"
  }
}

Full API documentation

Explanation

Formula: Phot = Lux × 0.0001. Why: phot is tied exactly to lux through the square-centimeter to square-meter area relationship, so the route normalizes through lux before applying the target unit.

Lux (lx): the SI derived unit of illuminance, equal to one lumen incident on one square meter of surface area.

Phot (ph): a CGS illuminance unit equal to one lumen per square centimeter, which is exactly 10,000 lux.

This route is useful when comparing phot-based CGS illuminance values against modern lux-based references in laboratory, optical, and legacy technical material.

This conversion is purely multiplicative because both units reduce through lux using fixed illuminance definitions with no offset.

Method & Reference

Method basis: exact conversion formula shown in Snapshot.
Applied factor: 1 Lux = 0.0001 Phot (using exact lux-based illuminance definitions).
Consistency rule: calculator output and table values use the same constants and rounding policy.

Common Conversion Values

Lux (lx)	Phot (ph)
1	0.0001
10	0.001
50	0.005
100	0.01
300	0.03
500	0.05
1,000	0.1
10,000	1

Questions & answers

Frequently Asked Questions

What is 1 lux in phot?

1 Lux equals 0.0001 Phot on this page.

Does this Lux to Phot page use the exact lux relationship for phot?

Yes. Phot routes use the exact relationship 1 phot = 10,000 lux through one lux normalization path, so CGS and modern lighting references stay consistent across the page.

When would I convert lux to phot?