Finding The Sweet Spot: How Luminance Affects Lighted Sign Legibility

Finding The Sweet Spot: How Luminance Affects Lighted Sign Legibility

Synthesizing findings from the Interdisciplinary Journal of SIgnage, ISA, and United States Sign Council, today’s post explains how to find the perfect luminance level for your custom lighted signs.

Read on or call 1-248-354-8346 to start a free lighted sign consultation in Southfield, MI.

How Luminance Affects Lighted Sign Visibility In Southfield, MI

If lighted signs are not set at the appropriate light level for the given ambient brightness (i.e. the level of light around the sign), the message will appear either too dim, in which case it will be difficult to detect, or it will be too bright, reducing legibility through overflow or blooming of the sign copy.

For best results, Southfield businesses need to find the sweet spot, that perfect level of luminance that draws the eye without blurring the message or causing any visual discomfort for the viewer.

To determine the optimal luminance for your specific lighted sign product, call 1-248-354-8346 to start a free lighted sign consultation.

For more general luminance guidelines, read on for a review of some key research findings from the Interdisciplinary Journal of Signage and Wayfinding, the International Sign Association (ISA), and the United States Sign Council Foundation (USSCF).

What Is The Best Brightness Level For Lighted Signs In Southfield, MI?


(ISA, 2016, p. 8)

                                                    (ISA, 2016, p. 8)


  • The sweet spot changes depending on the time of day. One report by the USSCF recommends a 50 percent voltage reduction from daytime to nighttime conditions, while others suggest that at night signs should be dimmed to 20 percent of daytime brightness (Garvey, 2015, p. 3)
  • The sweet spot changes depending on lighted sign size. For small lighted signs (e.g. billboard dimensions of 11 x 22 ft, Garvey (2015) recommenders 300 candela per square metre (cd/m2), whereas very large signs (e.g. 20 x 60 ft) should have approximately 330 candela per square meter.

For more help understanding luminance levels, get in touch with our team using the contact information listed below.

Book A Free Lighted Sign Consultation In Southfield, MI

Ready to light up your brand message or storefront sign in Southfield, Michigan? We’re standing by to help.

SignScapes is a leading provider of lighted sign solutions for businesses of all sizes throughout Southfield and all the surrounding areas, including:

  • Rochester
  • Dearborn
  • Clawson
  • Royal Oak
  • Sterling Heights
  • Novi
  • Auburn Hills, and beyond

We also offer remote collaborations and lighted sign deliveries nationwide for clients located outside of Michigan.

Call 1-248-354-8346 or visit the SignScapes website to book a free consultation and get a same-day quote on any custom lighted sign order.


Garvey, P. M. (2015). PHASE 1: On-Premise Electronic Message Center (EMC) Nighttime Dimming Research Review and State of the Practice Industry Survey. Retrieved from


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