Emily,
Thanks for your question!
There are
rental lockers available at all four parks. The sizes are;
- Small: 12" x 10" x 17" (30.48 cm x 25.4 cm x 43.18 cm)
- Large: 15.5" x 13" x 17" (39.37 cm x 33.02 cm x 43.18 cm)
- Jumbo (Magic Kingdom park and Epcot only): 17" x 22" x 26" (43.18 cm x 55.88 cm x 66.04 cm)
If these are not big enough to store your car seat, you might consider another approach. When our kids were younger we brought our own stroller on vacations, so that we had both the security of the plug in car seat, but also the convenience of a stroller. For a day in the parks with a little one you will likely want a stroller, as carrying the seat around all day long can get pretty exhausting.
You can also rent strollers, both via Disney as well as via their featured provider. With Disney you can
rent a stroller whenever you are in one of the theme parks, or at
Disney Springs. With the featured provider you can get a stroller to use throughout your entire trip, including when you are back at your resort. While I don't see any options from them with docked child car seats, you might find something that works for you.
I hope that one of these options helps you with your trip planning. If we can help more, don't hesitate to write us back for more suggestions!
Have a Magical Vacation!
Doug