Circadian Rhythm Light Meter
Melanopic mEDI mDER EML M/P MI
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
A light meter that measures mEDI, mDER, M/P ratio, and EML for any light source using the camera.
Support your circadian rhythm by measuring the melanopic content of your light environment!
Designed for health-conscious individuals, lighting designers, workplace wellness consultants, and anyone interested in how light affects sleep, alertness, and well-being.
WHAT IS MELANOPIC LIGHT?
Your body's internal clock — the circadian rhythm — is to a large extent regulated by specialized cells in your eyes (ipRGCs) that are sensitive to blue light around 490 nm. Traditional lux meters only measure total brightness, but not all light affects your circadian system equally. This app measures the melanopic component — the light that actually drives your body's response.
KEY METRICS
• Melanopic Equivalent Daylight Illuminance (mEDI) — the primary CIE S 026 circadian metric
• Melanopic Daylight Efficacy Ratio (mDER) — compare circadian effectiveness of light sources
• Melanopic/Photopic Ratio (M/P) — balance between visual and circadian stimulation
• Melanopic Irradiance (MI) in W/m² per CIE standard
• Equivalent Melanopic Lux (EML) — for WELL Building Standard compatibility
• Color Temperature (CCT) and Illuminance (lux)
KEY FEATURES
• Actionable lighting recommendations based on time of day, mEDI and color temperature
• Light source type selection (daylight, LED, incandescent, halogen, fluorescent)
• Save measurements with timestamps and comments
• Built-in calibration for optimal accuracy
• Multilingual support, including english
• Customizable settings
IDEAL FOR
• Improving sleep quality — identify excessive evening blue light
• Boosting daytime alertness — ensure sufficient melanopic light exposure
• Human Centric Lighting (HCL) design and verification
• WELL Building Standard compliance using EML measurements
• Evaluating light therapy lamps and SAD devices
• Testing blue light blocking glasses effectiveness
• Research and education in circadian photobiology
THE RIGHT LIGHT AT THE RIGHT TIME
Bright, blue-rich light during the day promotes alertness and synchronizes your circadian rhythm. In the evening, reducing melanopic light allows melatonin to rise naturally, preparing your body for restful sleep.
ACCURACY
For optimal accuracy, use a common white paper when measuring. Hold it at eye level, illuminated by the light source you want to assess. Select the correct light source type for the most reliable melanopic estimates. While pre-calibrated for good results, optional calibration further enhances accuracy on your specific device.
Privacy Policy, https://contechity.com/circadian-light-meter/pp.html
End User License Agreement, https://contechity.com/circadian-light-meter/eula.html
FREE FOR A LIMITED TIME
Enjoy full functionality for a few weeks. After that, choose a one-time fee or subscription — still at a fraction of the cost of a dedicated device.
DEDICATED SUPPORT
Your feedback helps improve the app. Contact us at apps@contechity.com for support or suggestions.
Turn your phone into a circadian light meter today and take control of your light environment.
Ratings & Reviews
• Misc minor improvements
This is a new app. Please let us know what you think in a review!
The developer, Contechity AB, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Purchases
- Identifiers
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Contechity AB
- Size
- 40.9 MB
- Category
- Utilities
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 39 more
- English, Afrikaans, Bulgarian, Catalan, Croatian, Czech, Danish, Dutch, Estonian, Filipino, Finnish, French, German, Greek, Hindi, Hungarian, Icelandic, Indonesian, Italian, Japanese, Korean, Latvian, Lithuanian, Malay, Norwegian Bokmål, Polish, Portuguese, Romanian, Russian, Serbian, Simplified Chinese, Slovak, Slovenian, Spanish, Swedish, Thai, Traditional Chinese, Turkish, Ukrainian, Vietnamese
- Age Rating
16+
- 16+
- Frequent
Medical Treatment information
Contains
Health or Wellness Topics
- In-App Purchases
Yes
- Full Access (Month) $0.99
- Full Access (Lifetime) $9.99
- Copyright
- © 2026 Contechity