Ratio calculator
Simplify any ratio to its lowest terms, scale a ratio up or down by a multiplier, or split an amount between two parts in a given ratio. Three modes in one with plain-English explanations.
Ratios come up constantly in personal finance. Your loan-to-value ratio is essentially a ratio of debt to equity. When two people buy a property together with different deposits, splitting costs and future proceeds fairly requires ratio maths. Pension contribution rates are ratios. Even your income tax splits your salary in a ratio of take-home to deductions. Understanding ratios makes these conversations much clearer.
What is a ratio?
A ratio compares two quantities and shows their relative sizes. A ratio of 3 : 2 means for every 3 of one thing there are 2 of another. The order always matters.
Simplifying ratios
A ratio is simplified by dividing both parts by their greatest common divisor. 12 : 8 and 3 : 2 and 6 : 4 all represent the same relationship - 3 : 2 is just the simplest form.
Ratio vs fraction vs percentage
A ratio of 3 : 2 means A is 3/5 of the total (60%) and B is 2/5 (40%). All three ways of expressing the relationship are equivalent - just different formats.
Ratios in property
When two people buy a property together with different deposits, any future sale proceeds should usually be split in the same ratio as the original contributions - not 50/50.
Please note: This calculator is for general mathematical guidance only. Results are rounded to two decimal places where appropriate. For financial decisions involving ratios or profit splits, always seek appropriate legal or financial advice to ensure arrangements are correctly documented.
Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly; always verify figures with an appropriate professional or official source before acting on them.
What does the ratio calculator do?
The ratio calculator simplifies ratios, converts them to percentages, and divides a total amount in a given ratio. It covers the ratio calculations most commonly encountered in financial contexts – debt-to-income ratios, investment allocation splits, and shared cost calculations.
Where ratios appear in financial life
Debt-to-income ratio: Total monthly debt payments divided by gross monthly income. Lenders use this to assess mortgage affordability – a DTI below 36% is generally considered manageable.
Savings rate: Monthly savings divided by monthly income – the ratio of income saved versus spent.
Portfolio allocation: The split between equities and bonds (60:40, 80:20) in an investment portfolio.
Shared costs: Splitting a joint expense (household bills, shared purchase) in proportion to income.
The information on this site is for educational and informational purposes only. Nothing on Be More Peter constitutes financial advice, and nothing should be treated as such. The calculators, articles and tools on this site are designed to help you understand financial concepts and run indicative numbers - they are not a substitute for professional advice tailored to your specific circumstances. Before making any financial decision - including decisions about mortgages, pensions, investments, savings or insurance — you should seek independent financial advice from a qualified adviser who is authorised and regulated by the Financial Conduct Authority (FCA). Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly - always verify figures with an appropriate professional or official source before acting on them. Be More Peter is not authorised or regulated by the FCA. The content on this site does not constitute a financial promotion.