reserved or no reserve JR Pass

I'll be travelling using JR Pass from tokyo to kyoto on tuesday and come back to tokyo on sunday with 4 year old child.
Do you think i need to reserve the seat or not?? if i reserve the seat, will my child get a seat?
Thanks

I always make seat reservations just for the peace of mind. It takes just a minute and costs around 300-700 Yen per person.

However, since you travel with a 4 year old child, the situation is a little bit more complex. You may be aware of this, but I am going to mention it, nevertheless.

Four year olds travel for free, unless they occupy a reserved seat, in which case you have to pay child fare (half price). So, there are two ways to avoid paying the child:

1) your child sits on your lap (not sure whether this is practical with a 4 year old)

2) you use non-reserved seats

Whether trains are crowded or not depends on the time of the day and some other difficult to predict factors.

But generally speaking: if your journey starts at Tokyo Station (the first station of the train service), then you can relatively easily secure a seat by lining up on the platform early enough.

But in case of Kyoto Station, there is a bigger chance that the non-reserved seats are already occupied, because it is not the first station of the train service (it comes from Osaka, Okayama, Hiroshima or Fukuoka).