FINANCIAL MATH, ON YOUR DEVICE

Free Finance & Business Calculators

Investment, profit, real-estate and startup math, computed on your device with no sign-up

▸ Your numbers stay on this device. FinCalcs runs every formula in your browser and never uploads or stores what you type.

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FinCalcs is a plain collection of calculators for investing, pricing, real estate and startups. Every tool runs entirely on your device: the numbers you type never leave the page, there is no account, and nothing is tracked.

Each calculator covers one standard formula with a worked example and a short FAQ. Pick a group below, or jump straight to the tool you need.

Everything here is one standard formula per page: what it does, how the math works, a worked example with real numbers, and the questions people actually ask. No accounts, no paywall, no email capture — open the tool, type your numbers, read the result.

If you are new to these metrics, start with compound interest and the rule of 72 to understand growth, then move to ROI and break even for business decisions. The real estate and SaaS groups cover the numbers that lenders and investors look at first. Each page links to the related formulas, so you can follow a theme from one calculator to the next.

Bookmark the pages you use most: the growth group for investing questions, the profit group for pricing, the real estate group for property math, and the SaaS group for subscription metrics. Everything stays current with no maintenance from you.

Bookmark the ones you need most and come back anytime — the tools are always here, always free, and always running on your own device.

Thank you for visiting, and come back whenever the numbers need checking.

Growth & Return

CAGR CalculatorMeasure the smoothed annual growth rate of an investment.Compound Interest CalculatorSee how a lump sum grows with compounding interest.Rule of 72 CalculatorEstimate how fast your money doubles, with the exact doubling time too.Future Value CalculatorFind what a sum today becomes after earning a steady rate.Present Value CalculatorWork out what a future amount is worth today.Annuity CalculatorCalculate the payment for a loan or an annuity.

Profit & Margin

ROI CalculatorWork out the return on an investment and how fast it pays back.Break Even CalculatorFind your breakeven point in units and revenue.Profit Margin CalculatorCalculate gross and net profit margins from one set of inputs.Markup CalculatorPrice from cost with markup, and convert between markup and margin.NPV CalculatorDiscount future cash flows to their present value.IRR CalculatorFind the internal rate of return of a project.WACC CalculatorWork out the weighted average cost of capital.

Real Estate & Credit

Cap Rate CalculatorWork out the capitalization rate of an income property.Cash on Cash Return CalculatorMeasure the return on the cash you actually put into a rental.DSCR CalculatorCheck whether a property income covers its debt payments.LTV CalculatorWork out your loan-to-value ratio and equity share.Debt to Income CalculatorSee how much of your income goes to debt and where you sit vs the 43% rule.

Startups & SaaS

Burn Rate CalculatorTrack how much cash your startup burns each month.Runway CalculatorSee how many months your startup can survive at the current burn.MRR CalculatorWork out monthly recurring revenue and convert it to annual.Churn Rate CalculatorMeasure customer churn and estimate yearly retention.LTV CAC CalculatorCheck whether customer value outgrows acquisition cost.Customer Acquisition Cost CalculatorWork out how much each new customer costs to acquire.Unit Economics CalculatorSee per-customer profit and the volume needed to break even.

Investment Fees

Investment Fee CalculatorSee how fund fees and expense ratios erode long-term returns.

Every calculator is free, runs entirely on your device, and never asks for an account.