Answer: Not very big.
Above is a scale map of St. Kitts beside a small area of Toronto.
That's right -- driving from one side of the island to another is roughly the same distance as heading up the DVP.
Mind you, it could be a bit slower with the winding roads. Or faster if you're comparing to rush hour :)
And Toronto certainly doesn't look like this:
Either way, it's a great little tropical paradise.
Be sure to give us a shout if things get a little cold where you are and you'd like to visit! :)