# Light Unit Converter

> Converts between light units for various light sources. (iPhone/iPad app by Apogee Instruments.)

- Source: https://appshunter.io/ios/app/light-unit-converter/id974693252 (this page in markdown: same URL + `.md`)
- Developer: [Apogee Instruments](https://appshunter.io/developer/955609109)
- Category: Business, Utilities
- Price: Free
- Rating: 5.00/5 from 3 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 8.0 · 6 MB
- Languages: American English
- Released: 2015-04-04
- Data updated: 2026-06-04
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/light-unit-converter/id974693252/reviews.md

## What is Light Unit Converter?

The Light Unit Converter app from Apogee Instruments calculates the conversions between different light units for various light sources including T5 Sylvania fluorescent lights, metal halide, high pressure sodium, and sunlight. Units include shortwave radiation (SW), photosynthetic photon flux (PPF, PPFD), Lux (lx) and Foot-candles (fc, lm/ft2, or ft-c).

Definitions:

Shortwave Radiation - Shortwave radiation (SW) is radiant energy with wavelengths in the visible (VIS), near-ultraviolet (UV), and near-infrared (NIR) spectra. There is no standard cut-off for the near-infrared range; therefore, the shortwave radiation range is also variously defined. It may be broadly defined to include all radiation with a wavelength between 0.1μm and 5.0μm or narrowly defined so as to include only radiation between 0.2μm and 3.0μm. There is little radiation flux (in terms of W/m²) to the Earth's surface below 0.2μm or above 3.0μm, although photon flux remains significant as far as 6.0μm, compared to shorter wavelength fluxes. UV-C radiation spans from 0.1μm to .28μm, UV-B from 0.28μm to 0.315μm, UV-A from 0.315μm to 0.4μm, the visible spectrum from 0.4μm to 0.7μm, and NIR arguably from 0.7μm to 5.0μm, beyond which the infrared is thermal. Shortwave radiation is distinguished from longwave radiation.

Lux - The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square meter. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watts per square meter, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human visual brightness perception.

Photosynthetic Photon Flux - Photosynthetic Photon Flux (PPF), also known as Photosynthetic Photon Flux Density (PPFD) or Photosynthetically Active Radiation (PAR), designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. PAR measurement is used in agriculture, forestry and oceanography. One of the requirements for productive farmland is adequate PAR, so PAR is used to evaluate agricultural investment potential. PAR sensors stationed at various levels of the forest canopy measure the pattern of PAR availability and utilization. PAR is normally quantified as µmol photons/m2/s, which is a measure of the photosynthetic photon flux (area) density, or PPFD. PAR can also be expressed in energy units (irradiance, W/m2); this is relevant in energy-balance considerations for photosynthetic organisms. Because photosynthesis is a quantum process, PPFD is generally used by plant biologists.

Foot-candle - A foot-candle (sometimes foot candle; abbreviated fc, lm/ft2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity widely used in the United States in photography, film, television, conservation lighting, greenhouse horticulture, the lighting industry, construction-related engineering and in building codes. The name "footcandle" conveys "the illuminance cast on a surface by a one-candela source one foot away". The unit is defined as the amount of illumination the inside surface of a one-foot-radius sphere would be receiving if there were a uniform point source of one candela in the exact center of the sphere. Alternatively, it can be defined as the illuminance on a one-square foot surface of which there is a uniformly distributed flux of one lumen. Thus one foot-candle is equal to one lumen per square foot or approximately 10.764 lux. In practical applications, as when measuring room illumination, it is very difficult to measure illuminance more accurately than ±10%, and for many purposes it is quite sufficient to think of one footcandle as about ten lux as is typically done in the lighting industry.

## Key features

- Converts between light units
- Supports various light sources
- Calculates shortwave radiation
- Measures photosynthetic photon flux (PPF, PPFD)
- Converts lux and foot-candles

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/light-unit-converter/id974693252/reviews.md

### 5/5 — Lux to PPFD Conversion

*2020-09-03*

is the conversion from LUX to PPFD just an estimate? out of the selection for lighting what can i use to measure my LED ?

## Frequently asked questions about Light Unit Converter

### What light units can Light Unit Converter convert between?

Light Unit Converter can convert between shortwave radiation (SW), photosynthetic photon flux (PPF, PPFD), Lux (lx), and Foot-candles (fc, lm/ft2, or ft-c).

### What types of light sources does Light Unit Converter support?

The app supports conversions for various light sources including T5 Sylvania fluorescent lights, metal halide, high pressure sodium, and sunlight.

### Is Light Unit Converter free to use?

Yes, Light Unit Converter is available for free and does not contain advertisements or in-app purchases.

### What is the age rating for Light Unit Converter?

Light Unit Converter has an age rating of 4+, making it suitable for a wide range of users.

### On which devices can I use Light Unit Converter?

Light Unit Converter is compatible with iPhones, iPads, and iPods.

### How often is Light Unit Converter updated?

The app was last updated on August 31, 2018, with version 1.0.3. Future updates will depend on developer plans.

### What is the user sentiment for Light Unit Converter?

Based on the available data, Light Unit Converter has a perfect rating of 5.0 stars from 3 ratings, indicating very positive user sentiment.

## Version history (last 4 releases)

### 1.0.3 — 2018-08-31

This app has been updated by Apple to display the Apple Watch app icon.

Updated view positioning problems.
Added support for iPhone X and iPad Pro.

### 1.0.2 — 2018-08-25

Increased input length from 4 to 12 (definitely overkill)
Updated app icon

### 1.0.1 — 2015-05-18

Minor bug fixes.

### 1.0.0 — 2015-04-04

No release notes.

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## More apps by Apogee Instruments

- [Field of View Calculator](https://appshunter.io/ios/app/field-of-view-calculator/id955609110)
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All apps by Apogee Instruments: https://appshunter.io/developer/955609109

## Related topics

[apogee instruments](https://appshunter.io/ios/topics/apogee-instruments)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-04.*