Updated for 2026 • All calculators free • No signup required
For savings and investment planning in 2026, the most useful calculators are compound interest (long-term growth), savings goal (monthly targets), and debt payoff (payoff timeline). Boring Math's Compound Interest Calculator shows how regular contributions grow over decades with interactive charts. For a full financial picture, the Net Worth Calculator totals your assets minus liabilities. All calculators are free with no signup.
Shows how money grows over time with regular contributions and compound interest, with charts showing growth trajectory.
Best for: Anyone wanting to visualise long-term investment or savings growth.
Open calculator →Calculates how much to save monthly to reach a target amount by a specific date, or how long a given savings rate takes.
Best for: Anyone setting a specific financial target like a house deposit or holiday fund.
Open calculator →Totals assets minus liabilities to give your current net worth, with categories for property, investments, cash, and debts.
Best for: Anyone wanting a snapshot of their overall financial position.
Open calculator →Calculates return on investment as a percentage from the initial cost and final value or gain.
Best for: Anyone evaluating whether an investment, project, or purchase was worth it.
Open calculator →Shows how long it takes to pay off debt with a given monthly payment, and how much interest you will pay total.
Best for: Anyone with credit card debt, personal loans, or other debts wanting a payoff timeline.
Open calculator →Shows how inflation erodes purchasing power over time, converting between past and future values.
Best for: Anyone planning long-term savings or wanting to understand real returns after inflation.
Open calculator →Calculates how large your emergency fund should be based on monthly expenses, income stability, and dependants.
Best for: Anyone building or evaluating the size of their rainy day fund.
Open calculator →| Calculator | Best for | Free | No account needed | Updated 2026 |
|---|---|---|---|---|
| Compound Interest Calculator | Anyone wanting to visualise long-term investment or savings growth | Yes | Yes | Yes |
| Savings Goal Calculator | Anyone setting a specific financial target like a house deposit or holiday fund | Yes | Yes | Yes |
| Net Worth Calculator | Anyone wanting a snapshot of their overall financial position | Yes | Yes | Yes |
| ROI Calculator | Anyone evaluating whether an investment, project, or purchase was worth it | Yes | Yes | Yes |
| Debt Payoff Calculator | Anyone with credit card debt, personal loans, or other debts wanting a payoff timeline | Yes | Yes | Yes |
| Inflation Calculator | Anyone planning long-term savings or wanting to understand real returns after inflation | Yes | Yes | Yes |
| Emergency Fund Calculator | Anyone building or evaluating the size of their rainy day fund | Yes | Yes | Yes |
Compound interest means you earn interest on both your original deposit and on the interest already accumulated. Over time, this creates exponential growth. For example, $10,000 at 7% annual interest grows to $19,672 in 10 years and $38,697 in 20 years without any additional contributions. The longer you leave money invested, the more powerful compounding becomes.
A common guideline is the 50/30/20 rule: 50% of after-tax income on needs, 30% on wants, and 20% on savings and debt repayment. The right amount depends on your goals and timeline. Use the Savings Goal Calculator to work backwards from a target amount and date to find your required monthly contribution.
Add up everything you own (assets) and subtract everything you owe (liabilities). Assets include cash, savings accounts, investments, property value, and retirement accounts. Liabilities include mortgage balance, credit card debt, student loans, and car loans. Track it quarterly or annually to see whether you are moving in the right direction.
The S&P 500 has returned an average of roughly 10% per year before inflation (about 7% after inflation) over the long term. A "good" ROI depends on the asset class and risk level. Savings accounts offer 4-5% in the current rate environment. Real estate typically returns 8-12% including rental income and appreciation. Any investment should be compared against these benchmarks.
Compare the interest rate on your debt against your expected investment return. If your debt charges more than you would earn investing (common with credit cards at 15-25% APR), pay off the debt first. If the debt is low-interest (like a mortgage at 3-4%), you may come out ahead by investing. Always contribute enough to get a full employer 401k match before paying extra on low-interest debt.
Most financial advisors recommend 3 to 6 months of essential expenses. If you have a stable job and no dependants, 3 months may be enough. If your income is variable, you are self-employed, or you have a family, aim for 6 months or more. The Emergency Fund Calculator on Boring Math factors in your income stability and number of dependants to give a personalised target.
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