Estimate spousal and child support based on the SSAG and Federal Child Support Guidelines across all Canadian provinces. Note, this tool only provides an estimate and is not meant to be a substitute for legal advice.
Understanding what you may owe — or receive — is one of the first questions people ask when a marriage or common-law relationship ends. Our free Ontario child support and spousal support calculator gives you an evidence-based estimate in minutes, using the same Federal Child Support Guidelines and Spousal Support Advisory Guidelines (SSAG) that lawyers and judges rely on across Canada. Whether you are in Toronto, Oakville, Mississauga, or anywhere else in Ontario, the same federal framework applies.
This page explains how each type of support is calculated, what factors affect the outcome, and where a family lawyer adds value beyond any online calculator.
Child support in Canada is governed by the Federal Child Support Guidelines, which set out a schedule of monthly "table amounts" based on two variables: the paying parent's gross annual income and the number of dependent children. The table amount is updated periodically by the federal government and differs by province, because provincial income tax rates affect net disposable income.
In most cases involving sole custody — where the child lives primarily with one parent — the higher-income parent pays the table amount to the lower-income parent. The receiving parent's income is not relevant to the table amount; only the payor's income and the number of children matter.
Shared custody — where the child spends at least 40% of time with each parent — is treated differently. In shared arrangements, both parents' incomes are considered and the support obligation is often offset, meaning each parent's table amount is calculated and the difference is paid by the higher earner to the lower earner.
On top of the table amount, parents must share certain additional expenses proportionate to their incomes. These include childcare costs that allow a parent to work, health and dental insurance premiums for the child, extraordinary extracurricular activities, and post-secondary education expenses. Our calculator provides the table amount — your lawyer will help you address Section 7 expenses in your separation agreement.
Child support is treated as a right of the child in Canadian law, not a right of the receiving parent. This means it cannot be waived by agreement between the parents, and courts can override arrangements that do not meet the guideline amounts if they are not in the child's best interests.
Spousal support is more complex than child support because there is no single formula — entitlement, amount, and duration all involve discretion. However, the Spousal Support Advisory Guidelines (SSAG) provide a widely-used framework that gives lawyers and judges a range of reasonable outcomes to work within.
The SSAG use two primary formulas depending on whether child support is also being paid. The "without child support" formula applies when there are no dependent children. It calculates a support range as a percentage of the income difference between spouses, scaled by the length of the relationship. The longer the marriage or cohabitation, the higher the percentage of the income gap that is shared, and the longer the duration of support.
The "with child support" formula applies when child support is also being paid. This formula uses a net income sharing approach: it calculates each party's net disposable income after taxes, government benefits, child support, and work-related childcare, then targets an outcome where the lower-income spouse retains between 40% and 46% of the combined net disposable income.
Under the SSAG, duration is generally calculated at 0.5 to 1 year of support for every year of cohabitation. A 10-year marriage typically produces a range of 5 to 10 years of support. Marriages of 20 years or more often result in indefinite support — meaning there is no fixed end date, though the amount can still be varied over time as circumstances change.
The SSAG produce a low, mid, and high range for both amount and duration. Our calculator shows all three scenarios so you can understand the realistic range of outcomes, not just a single number. Where within that range the actual support lands depends on the specific facts of your situation, negotiation, and — if necessary — a court's assessment.
Both parties' gross employment income is the primary driver of support amounts. Self-employment income, investment income, and imputed income add complexity that requires a lawyer's analysis.
Years of marriage and cohabitation directly determine spousal support duration. In Ontario, common-law cohabitation counts the same as legal marriage for support purposes after three years, or sooner if there is a child.
The number of dependent children determines the child support table amount. Ages matter because children age out of support, and shared vs. sole custody arrangements significantly change the calculation.
Each province has its own child support table because provincial tax rates differ. In cross-province situations — common in Ontario when one spouse has moved — the payor's province of residence generally governs the table amount.
Our support calculator is built on the same formulas used by family lawyers across Canada, and for most situations it gives you a reliable range to begin your planning. However, every separation involves facts that no calculator can fully capture.
If either spouse is self-employed, owns a business, or earns variable income from commissions or bonuses, determining the correct income figure for support purposes is itself a legal and accounting exercise. Courts have broad authority to "impute" income — attribute income that is higher than what was actually declared — where a party has deliberately reduced their income to lower support obligations.
Similarly, spousal support entitlement is not automatic. A spouse must demonstrate a legal basis for support — typically compensatory (career sacrifice during the relationship), non-compensatory (need), or contractual (marriage agreement). A family lawyer assesses entitlement before calculating amount and duration.
Use the calculator above to orient yourself before your consultation. It will help you ask better questions, understand the range of outcomes, and approach negotiations from an informed position.