Commission is negotiated with your listing agent and is the largest variable in the calculation, since it's a percentage of sale price rather than a flat fee. It's worth confirming the exact split and rate in writing before you list, since it directly changes your net number.
Your mortgage discharge is the other big variable. If you're breaking your mortgage term early, ask your lender for the exact penalty now rather than at closing, since a prepayment penalty can run into the thousands depending on your remaining term and rate.
Your lawyer's statement of adjustments, prepared before closing through Information Services Corporation, itemizes every deduction so you know your final number before possession day. Get your hand-reviewed valuation from Joel Dyck.