The calories in sushi can vary a lot just because some places tend to like adding mayo to practically everything. You can also get a big variety just in how the rolls are put together - I ordered an avocado roll from a restaurant I hadn't tried before, and instead of a simple roll with avocado only in the middle, I got one with avocado in the middle and a layer of avocado outside over the rice, which I'm sure hugely boosted the calorie count.
Whenever I order sushi I always get California rolls and avocado rolls, but make sure to request they make it without mayo. I also don't use soy sauce, since if I eat it I end up bloated the next day without fail.
For your standard california roll (imitation crab meat, avocado, rice, seaweed) it's ~250, and for a small avocado roll (avocado, rice, seaweed) it's ~160.