This one-of-a-kind calculator will give you a reasonable estimate of what your closing costs are likely to be.

What is the purchase price? (not incl. HST) $
What is your interest rate? %
What is your mortgage amount? $
What day of the month is your deal closing?
Is your home located in Toronto?
Is this a condominium?
Is this a newly built home?
Are you a first-time home buyer?

For a detailed explanation of each specific cost, check out this post:
Closing Costs - The Stomach Punch of the Home Buying Process