Use this free calculator to calculate spousal support according to the Canadian Spousal Support Advisory Guidelines, as well as child support (if applicable). You should keep in mind that this free online calculator only considers employment income and can only do simple calculations.To determine how much spousal support is required, calculate your gross income. This is the amount of money you make after taxes and other deductions. There are two basic formulas used to calculate alimony in Ontario: the Without Child Support formula and the With Child Support formula. Use our calculator for Canadian spousal support estimates to help you understand what your support payments may look like. The calculation of spousal support is one of the most complex areas of family law. Spousal support is your monetary obligation to your spouse after separation or divorce. The purpose is to ensure financial support for their well-being. Many people also refer to spousal support in Ontario as maintenance or alimony.