LRV Guru™ App from The Land of Color


Download LRV Guru on App Store

NOTE: You cannot take a picture of a color and ascertain LRV.

You must use a Color Muse hand-held colorimeter to MEASURE color.

Guru App How To Video – Less than 10 minutes

Bonus Part 2 – Determine Hue Family of a Color Using Color Muse




The LRV Guru app assists with calculating color contrast ratios.  It does the math for you.  Scan samples with a tool called the Color Muse (info below) or enter manufacturer LRV data. LRV is an acronym that stands for Light Reflectance Value.  LRV is a measurement that tells you how much light a color reflects and conversely how much it absorbs. LRV runs on a scale from 0% black to 100% white.

NOTE: You cannot take a picture of a color with your smartphone or camera and ascertain LRV. A picture of a color is just a captured image, it is NOT A MEASUREMENT! You must use a Color Muse hand-held colorimeter to measure color.


Color consultants, architects, graphic designers, sign makers, lighting and interior designers use LRV data in several stages of color design planning.  Homeowners should use LRV as a benchmark as they choose colors because LRV indicates how much two colors will contrast or blend as well as how light or dark a color could look and feel once applied to walls.


Careful planning for proper visual ergonomics is paramount in color design for the built environment. Human supportive color palettes are important because the average observer will see hue differences first, chroma differences second, and contrast, lightness differences last. Examples where this is applied are doorways, ramps, steps, signage, and work surfaces.


Meeting LRV specifications is critical to maintain the integrity of exterior architectural elements like doors and vinyl siding. In addition, guidelines for LRV contrast ratios exist in many industries and are intended to ensure good visual ergonomics for everyone especially the visually impaired.


There is a standard mathematical formula predicated on LRV data points that has been used for decades to calculate the color contrast ratio between two colors.  The LRV Guru app performs that calculation for you.  Enter known manufacturer LRV data points if you have them or use the Color Muse (info below) to scan swatches of colors.


LRV Guru’s default contrast ratio is set at 70% because it is the most commonly applied guideline. A significant bonus feature of the app is that the contrast ratio can be adjusted by tapping “settings” and positioning the slide bar as desired.

TOOLS – D65 Illuminant 2° Observer

LRV Guru™ is integrated with the Color Muse. A hand-held color sensor that integrates cutting-edge light technology to compute accurate spectral values, regardless of ambient light.

Color Muse

color muse
color muse specs

Accurate color captures for color professionals to quickly match paint, textiles, carpet, tile, accessories and more. The Color Muse device is the latest color scanning technology that allows you to scan smooth or textured surfaces. … Scan colors and instantly find hue family, LRV, value, and chroma!



  • 90%+ match on fan decks

  • <1 dE avg. on 2000 colors

  • <0.25 dE avg. inter-instrument agreement


  • 4mm diameter area

  • D65 Illuminant

  • 2 deg. std. observer

  • 45/0 measuring optics

  • White calibration cap


  • Tri-stimulus XYZ sensor

  • Full spectrum white LEDs

  • Patented and patent pending color algorithms



  • iPhone 5 or newer

  • iPad 3rd gen or newer

  • Color Muse Only – Android 5.0 or newer

  • must have Bluetooth 4.x


  • 280 mAh lithium-polymer

  • 3,000 scans

  • 6 months standby time

  • USB charging


  • 1.08 inch / 27.5mm diameter

  • 2.17 inch / 55mm tall

  • 1 oz / 29g weight


  • Bluetooth 4.1

  • USB

Stop guessing about color and start controlling it – buy Color Muse and LRV Guru now!

LRV Guru™ + Color Muse = Unmatched Color Power!

NOTE: You cannot take a picture of a color with your tablet, smartphone, or camera and ascertain LRV. A picture of a color is just a captured image, it is NOT A MEASUREMENT! You must use a Color Muse hand-held colorimeter to measure color.


IMPORTANT! Defer to LRV data provided by manufacturer if available.

Disclaimer: Color Strategies, LLC is an Amazon affiliate.


Spectral data captured with Color Muse and the values and/or ratios ascertained using LRV Guru app are reasonably informative guidelines. Use a certified color lab for requirements beyond reasonably informative guidelines.

  • Matthew Noall

    App does not connect to sensor. Color Muse app works fine. I reinstalled this app but no affect

    • Hi Matthew,

      I’m so sorry you’re having difficulty connecting LRV Guru to the Color Muse. I just tested it and I’m connecting to the app rather quickly – no issues. I reached out and asked another user to see if they could connect and they too were able to connect to the LRV Guru app within seconds.

      Let me know if you’re still having issues and I’ll see how or if I can help.

      • Paul

        I am having the same issue. The lrv guru app finds my color muse and when I select the device to pair it, nothing happens. I reinstalled the app but it keeps doing the same thing. It highlights the device in grey and then nothing happens for over a minute. The muse app works fine but the lrv guru app gets stuck at selecting the device

        • Thanks for stopping by to let me know there is an issue, Paul. I believe something updated in the last few days somewhere in the loop of the Color Muse, Apple, and the app. My developer is working on it right now.

          Updates have happened before that have affected the function of the app so nothing out of the ordinary and I know it will get fixed, it’s just very inconvenient for my app users! I appreciate your patience while we work through this.

  • Cathy

    Hi Lori. I just purchased the muse and downloaded the free app which works. I bought your app and it won’t connect. So is this still having the issues that the other people were talking about above?

  • Cathy

    This app does not work at all. It is supposed to work with the Muse. When the muse button is pressed so it can recognize it, the lrv guru app does not recognize it and so it never connects. However, the Muse software app works fine and has no problem connecting. So this is obviously an issue with the lrv guru app only. I would either like to get a reply and have this fixed or get my money back.
    Could you please reply to this. I have not gotten any response. Thank you.

    • Toggling back and forth between apps causes a bit of “confusion” for the device and you have to reset the Color Muse.

      Whenever the Color Muse won’t connect, hold down the button for 20 to 30 seconds. The blue light will flash and then it will stop. That should be enough to clear it so LRV Guru can recognize it and you can connect.

      • Oh, and this may seem obvious, but make sure the Color Muse is fully charged. It’s best to charge it via a wall outlet vs. USB port.