When you REGISTER FREE and become a member at Spot Gravity, you’ll most likely see that a lot of the copy pieces are numbered. Well, there’s a bit of logic behind all of this.


Most radio ads are either 60, 30, 15 or 5 seconds in length. Given that fact, you can approximate how long your spot is by numbering the lines you write.

First open up a program like Microsoft Word and select a standard font – something like Arial or Times New Roman. Set your font size to 10. Next click on the numbering featured (near the bullet points area). Turn your CAPS on and we are ready to roll.

Use the following table to calculate how much text you can include:

Commercial Length:

Max Number of Lines:









Things to remember:

  • WRITE OUT ALL NUMBERS. For example, don’t type 100; type, ONE-HUNDRED. The reason is simple – pronouncing numbers take time. If you use digits when writing, you may fool yourself into thinking there’s more time
  • REMEMBER THE HUMAN FACTOR. Don’t forget that breathing and natural pauses in syntax must be accounted for. So try not to cram too much copy into an ad
  • USE A STOPWATCH. Always time things out with a good old fashioned watch. Read at a normal pace. This will let you know whether you’re close.