Free Financial Calculators: Interest, ROI & Business Costs
Compare interest, investment returns and business costs with free financial calculators. Choose a formula, check its assumptions and explore a worked example.
APR to APY Calculator
Convert between Annual Percentage Rate and Annual Percentage Yield with compounding frequency support
Compound Interest Calculator
Calculate compound interest growth over time
Simple Interest Calculator
Calculate simple interest (I = P×r×t), total amount, and monthly schedule — free browser tool
ROI Calculator
Calculate return on investment
Profit Margin Calculator
Calculate profit and profit margin from cost and selling price.
Markup Calculator
Calculate markup on cost from cost and selling price.
Break-Even Calculator
Calculate break-even point in units and revenue for any business
CAGR Calculator
Calculate compound annual growth rate from start and end values
NPV Calculator
Calculate net present value (NPV) and IRR from cash flows and a discount rate
Loan Calculator
Calculate monthly payments and total interest
Mortgage Amortization Calculator
Generate a complete mortgage amortization schedule with monthly and yearly payment breakdown
Meeting Cost Calculator
Price any meeting by the people in the room — per meeting, per year, and in hours burned
How to choose and use these tools
- Use APR to APY to compare nominal rates with different compounding schedules, then model a balance with the compound interest calculator.
- For pricing, calculate markup on cost and profit margin on revenue separately; they use different denominators.
- Compare fixed costs and contribution per sale with the break-even calculator. Use meeting costs to estimate staff time.
Worked example
A product costs $80 and sells for $100: profit is $20, markup is 20 / 80 × 100 = 25%, and margin is 20 / 100 × 100 = 20%. A 25% markup does not give a 25% margin.
Frequently asked questions
Which interest calculator should I use?
Simple interest applies interest to principal only. Compound interest also earns interest on accumulated interest. APR to APY compares annual rates when compounding is involved; fees and taxes may require separate adjustments.
Are these results forecasts or financial advice?
They are mathematical scenarios based on your inputs. They do not predict returns or account for every fee, tax or change in rates. Check assumptions before making a financial decision.