Spin and Weight class question

Hi,

I don't own a fitbit or any real fitness intensity measurement tool. I do spin around once or twice a week ... I work hard but have no way of knowing what I'm burning.

The class I am most interested in is my weights one. It is a moderate-high intensity workout where I lift 8 kgs in total for around 50 minutes. Doing squats, clean and press, lunges, bicep curls, triceps, shoulders and back.

You can probably tell I am a bit of an exercise novice.. But I was just wondering if anyone had any ideas on how much I may be burning at these classes?

If it helps.. I am 5.7, 69 kgs