In this section, Part 4 of this series, we'll start by looking at more precise calculations for determining the area needed for a sign or banner.
Personally, I am not a big fan of algebra, but sometimes the easiest way to calculate what the Area of a sign (A[sign]) is by using one, especially if someone else has already done the work to come up with it, which, in our case, the USSC has already done for us.
How to Measure the Area of Signs or Banners
The only part of the equation that is left out is the negative space calculation, which is fixed at a 40/60 ratio with the copy area, or Copy Area x 1.5. Note that number rounding - which I do frequently - will yield a slight variance in copy area/negative space. As this is an inexact science to a degree, this rounding will likely have little effect on readability of your signs or banners. This is essentially the same formula used in Part 3, but it's simplified from the 10 step equation to this -
A(sign) = 3n/80 [(VRT)x(MPH)/LI]
40/60 ratio of copy area to negative space
N = number of letters
VRT = Viewer Reaction Time
MPH = Miles Per Hour b
LI = Legibility Index
Doing the Calculation
How do I use this equation in the real world? First, take the number of letters (N) and multiply it times 3, then divide that by 80. So, we'd take 3 x 60 /80 =.75. Set that number aside.
Next, we want to multiply our VRT - 10 seconds - times the MPH - 40mph = 400, divide it by the LI - 30 = 13.33 - and square it = 178 rounded up. Now multiply 178 x.75 and your sign's square footage would be 133.5. Much simpler than the longhand equation, methinks!
An even simpler equation, but with more fixed values, is this algebraic equation -
A(sign) = [(VRT)x(MPH)] x [(VRT)x(MPH)] / 800
Number of Letters - 30
LI (Legibility Index) - 30
Copy Area/Neg. Space - 60/40
VRT (Viewer Reaction Time)
MPH (miles per hour)
This equation works quite simply as you multiply view reaction time - 10 seconds - times the miles per hour - 50mph = 500 and then square it = 250,000 and divide it by 800 = 312. This is the area of your sign.
Now you'd need to know that you'll have 30 - 30 in. letters, which is a fixed value above, and that these letters will fit into this area. You may need to vary the sign area if the words require it, like we did on the Grand Opening banner in the last section.