Shimano technical documents will have the information you need. Just type your model number in, and you'll have the exploded view, installation manual, and potentially dealer guide at your fingertips.

The other points made so far are good to keep in mind. You can estimate for yourself using a gearing calculator and your drivetrain's tooth counts, plus what you know about your riding style and cadence. There will be larger gaps between cogs for a seven speed, but you can use the calculator to see how that might affect you. My personal experience is that the wide range cassette and my pace conflict, so that my comfortable cruising ratio is unavailable while in my largest chainring. I'm left with a slightly too low or slightly too high gearing. That's on a 9 speed, there are more opportunities for that to happen on a 7 speed.