Can you do both universal studios Orlando parks in one day?

It depends on a few factors: length of time the park is open, the crowds and the weather. If the Park is only open 7-9 hours, than no. If the crowds are holding up the line, No. If the weather storms and shuts down the outdoor rides, no.

However, if it is a long day - 10-12 hours, and you split up, you can do it. Also, invest in a fast pass. That will be a big help. Skip the shows and the kiddie rides. Put those last and you will be fine.

I would say no. You don't want to rush your day, especially on vacation. Also, remember there might be lines and delays that will cost you more time than you think. Universal is a great park, I've been there plenty of times, but I'm a young professional with no kids. I think it's best to take your time and not rush your kids. On the other hand, if you absolutely wanted to do both parks you would have to cut short the activities and attractions at one or both parks. Have fun :)

dont even think about it

i have just returned at the so called off peak season when the wait time was not more than 15 minutes at any place.

We barely managed to see islands on day 1 ( of course we did some rides more than once )

On day two we cut short the kiddies part at studio and completed the islands of adventure.

Harry Potter is being built and would be ready next summer hopefully

Not realistically. You could go early and map out just the rides/shows you want to see but you'll be rushing. All of the theme parks are designed to occupy you for an entire day. That's why they get $70 a head these days.

Yeeah, you can go to both in one day but you would have to go there early, (which is usually the best time to get there) and kind of rush through the parks so I would recommend going on different days.

And yes the Harry Potter World will be open then

It is possible but you would feel very rushed. I would suggest you do each park on a different day.

Hope this helps!

Possibly if you miss a few rides and there aren't too many people. I would recommend two days, one and a half at least.

Sure. Depends on how much time you have.