An average speaking rate is approximately 120 to 150 words per minute. However, estimating whether a text fits within 5 seconds, 30 seconds, or a minute is not always easy.
Numbers, in particular, make texts longer to pronounce than they appear. Consider this: when you pronounce the number '1,384,234,' it consists of 17 syllables (or 18, if you use the word 'and' between 'two hundred' and 'thirty four'), while having the same number of characters as 'strawberry.'
To truly know if your script fits within the time you have, it's best to read it aloud. Don't skip syllables and don't cheat. If desired, you can record yourself.