Where a lender does offer a point, the break-even calculation divides the upfront cost by the monthly saving the lower rate produces, giving the number of months you need to keep the mortgage before the upfront cost pays for itself, a number that varies file to file rather than following a fixed rule.
That math only works out if you keep the exact same mortgage for years without refinancing or selling, and Canadian mortgages compound semi annually rather than monthly, so a break-even figure from a US calculator will not match a Canadian lender's numbers.
A larger down payment usually saves more interest over the life of the mortgage than paying for points does, and above 20 percent down it also removes the CMHC, Sagen or Canada Guaranty insurance premium entirely, so it is worth comparing both before committing. Get your hand-reviewed valuation from Joel Dyck.