The observable universe has a diameter of 46 billion light-years. The only reason we can't see farther is because the rate of expansion of space itself makes it impossible for light to travel to us from beyond that distance.

46 billion light-years is far too great a distance to put into a meaningful context, but it gets crazier. If spacetime has either zero or positive curvature, it must be infinite. If it has negative curvature, it is finite (like a sphere but in four dimensions). Spacetime appears to exhibit zero or near-zero curvature, meaning that if the universe is finite, the difference in size between the observable universe and the total universe is (roughly) comparable to the difference in size between a human and the Earth.

Of course this really doesn't matter since nothing outside the observable universe is capable of interacting with anything that we will ever be able to observe.