Free Finance & Cost Calculators
Free finance and cost calculators — estimate loan payments, take-home pay, hosting bills, ad profitability and more. No sign-up, no ads tracking you around the web, every calculation runs locally in your browser.
Loans & Mortgages
Work out monthly payments, total interest and affordability before you sign anything.
Loan Payment Calculator
Enter the loan amount, annual interest rate and term to see your estimated monthly payment, the total interest you will pay, and the true total cost of the loan.
Mortgage Calculator
Estimate your full monthly housing payment — principal, interest, property tax and homeowner’s insurance (PITI) — and see how much house a given payment actually buys.
Investing & Returns
Measure how hard your money is working: compound growth, ROI and CAGR.
Compound Interest Calculator
Project the future value of savings or investments with compound growth — enter a starting balance, monthly contributions, expected annual return and timeframe.
ROI Calculator
Enter what you put in and what it is worth now to see your total return on investment (ROI) and the annualized (per-year) return.
CAGR Calculator
Compute the compound annual growth rate (CAGR) — the smoothed per-year growth rate that turns a beginning value into an ending value over a number of years.
Salary & Tax
Convert salary to hourly, estimate take-home pay and price your freelance work.
Salary to Hourly Calculator
Convert an annual salary into hourly, weekly, monthly and daily pay.
Take-Home Pay Calculator (US)
Estimate your net (take-home) pay in the US: enter gross annual salary, filing status and a state tax rate to see estimated federal tax, FICA and your monthly paycheck.
Freelance Hourly Rate Calculator
Work backwards from the income you want: enter your target income, tax rate, business expense share and realistic billable hours to get the hourly rate you actually need to charge.
Business & Hosting Costs
Know the true cost of running things: hosting, SaaS seats, employees, break-even.
Web Hosting Cost Calculator
Estimate your real monthly hosting bill: enter traffic, page size, storage and app instances to get bandwidth estimates and cost ranges across hosting tiers.
SaaS Subscription Cost Calculator
Total up your software spend: enter the number of tools, average per-seat price and team size to see monthly, annual and per-seat costs — plus what annual billing could save.
Employee Cost Calculator
A salary is only part of what an employee costs.
Break-Even Calculator
Find the exact point where a product stops losing money: enter fixed costs, your price per unit and the variable cost of making each unit.
Profit Margin Calculator
Enter revenue, cost of goods sold and operating expenses to see gross profit, gross margin, net profit and net margin — the two numbers that describe a business’s health.
Marketing & Growth
Judge every dollar of ad spend: ROAS, CPM, customer lifetime value and payback.
ROAS Calculator
Enter ad spend and attributed revenue to see ROAS, actual profit after product costs, and the break-even ROAS your gross margin requires.
CPM Calculator
Enter what you paid and how many impressions you received to get CPM — the standard rate card unit for comparing ad inventory across channels.
Customer Lifetime Value Calculator
Enter how customers buy (order value, frequency, margin, lifespan) and what you pay to acquire them, to see lifetime value, the LTV:CAC ratio and payback period.
Why CalcStack?
Most calculators give you a number and leave you guessing what it means. Every tool here pairs the calculation with the formula behind it, a step-by-step guide, and the context you need to act on the result — whether that is negotiating a rate, pricing your freelance work, or deciding whether an ad campaign is actually profitable.
All calculators are free, require no account, and run entirely in your browser: nothing you type is ever sent to a server.
From the blog
Guides with real numbers, each paired with the calculator that does the math.
15-Year vs 30-Year Mortgage: The Real Numbers
Choosing between a 15-year and 30-year mortgage is a tradeoff between monthly breathing room and lifetime interest.
How One Extra Payment a Year Cuts Years Off Your Loan
Extra principal payments are the quiet superpower of amortized loans.
APR vs Interest Rate: Compare the Right Number
Two loans can advertise the same interest rate and cost very different amounts.
The Rule of 72: Why Starting Early Beats Investing More
The Rule of 72 is the fastest mental math in finance: divide 72 by your annual return and you get the number of years for money to double.
CAGR vs Average Return: Beware the Volatility Trap
Averaging yearly returns is one of the most common ways investors fool themselves.
How to Evaluate an Investment with ROI (and Its Blind Spots)
ROI answers a deceptively simple question: for every dollar in, how many came out? Its simplicity is its power and its danger — the same simplicity hides time, risk and cost if you let it.