How many calories do you burn?

This depends so much on gender, age, weight, fitness level, and type of exercise. For me it varies depending on what I'm doing. An hour of aqua aerobics is around 480, an hour or so in the gym doing weights and cardio is usually around 550-650 (depending again on how hard I work, and what activities I do), and my swimming workout is typically around 700-900. My burns are higher as I'm quite heavy still, although I'm actually in decent shape and can push myself to do a lot (with swimming, I used to be a lifeguard and play water polo so I can easily swim at a decent pace for over an hour and I'm actually training for a swimathon at the moment).

Don't compare yourself against others, but simply do the best you can do and keep pushing yourself to improve. Great job joining a gym and getting active!

Varies. My goals at the gym though don't revolve around burning calories. They are just a tasty bonus. Currently, I want to get stronger (so Stronglifts 5x5) and I want to be able to run a 5k (so Zombies,Run!5k).

My burns can be anywhere from 100 to 500 calories depending on what I'm working on that day.

I have no idea. Any calculator is just an estimate. I did an hour of heavy lifting today, most likely that was somewhere around 250 - 300 calories. But again, I can’t be certain exactly how much, so I don’t lose sleep worrying about it. I eat what I think I need to fuel myself and I move on.

I burn way less than others. I've been in fitness classes where some people's garmins say 500 -600 and I burn like 150 lol. However, I am very fit and weigh 110, 5'4 and they were taller and larger than me so that makes sense.

I run primarily, and I burn ~95-110 calories per mile, depending on speed, elevation change, etc. So I'll usually get 300-700 calories back (daily) during the week, and up to 2000 on the weekend when I hit my longest run for marathon training. On the other hand, 25 minutes of rowing is only ~150 calories; this is why cross-training day makes me sad.