Originally Posted by badbrew
You measured off the added water at the end.
Measure again when everything is stirring up in the carboy. Tonight would probably be right.
Or there's more to it than you've said. Like...all the wort spilled out so I filled the kettle with tap water instead and now my reading is low.
Or the grainbill was for a 5 gallon batch and I now have 30 gallons, what happened?!
Your boil cannot cause anything like this.