Here is an online calculator that may be able to help you.
For income protection insurance, the level of cover available is limited to 75% of your Pre-Disability Income, to a maximum of $10,000 per month.
For income protection insurance
Yes. You can decrease your cover (subject to the minimum Sum Insured or premium requirements) at any time by contacting us. You can apply to increase your cover (up to the maximum amount, up to75% of your income to a maximum of $10,000* per month) at any time. To increase your cover you may need to answer some additional health and lifestyle questions.