Disability insurance is calculated as a percentage of your current salary, and usually offers coverage equal to about two-thirds of your earned income. If you bring home $5,000 a month when you're healthy, DI would pay about $3,300 a month if you were unable to work.
The good news is that while your paycheque is subject to income taxes, that $3,300 cheque is tax free provided you pay the premiums yourself!