Free Calculators
A calculator for everything: scientific, mortgage and payoff, rent-vs-buy, student loans, retirement and ROI, salary and take-home pay, inflation, loan and compound interest, BMI, age and date, tip, unit conversion, and more. Each one shows its working so you learn, not just get a number.
Scientific Calculator
Trig, logs, powers, factorials — full keypad.
Open tool → LivePercentage Calculator
Percent of, percent change, increase/decrease.
Open tool → LiveUnit Converter
Length, weight, temperature, and more.
Open tool → LiveTip Calculator
Split the bill fairly in seconds.
Open tool → LiveStudent Budget Calculator
Plan spending on a student budget.
Open tool → LiveAge Calculator
How old are you, exactly? Years, months, days.
Open tool → LiveDate Calculator
Days between dates, plus date arithmetic.
Open tool → LiveBMI Calculator
Body mass index with healthy-range guidance.
Open tool → LiveLoan Calculator
Monthly payments, interest, amortization table.
Open tool → LiveCompound Interest Calculator
Project savings growth with contributions.
Open tool → LiveMortgage Calculator
Monthly payment, PITI, and full amortization schedule.
Open tool → LiveMortgage Payoff Accelerator
What extra payments save in interest and years.
Open tool → LiveRefinance Break-Even
Closing costs vs monthly savings — your break-even month.
Open tool → LiveRent vs Buy
Honest multi-year cost comparison with appreciation.
Open tool → LiveHouse Affordability
What home price fits your income? The 28/36 rule.
Open tool → LiveStudent Loan Payoff
Avalanche vs snowball plans for your actual loans.
Open tool → LiveCollege Cost Estimator
Four-year costs, borrowing needs, loan payments.
Open tool → LiveCredit Card Payoff
Minimums vs fixed payments — time and interest.
Open tool → LiveDebt Payoff Planner
Snowball vs avalanche across all your debts.
Open tool → LiveAPR Calculator
The true annual cost of a loan, fees included.
Open tool → LivePresent & Future Value
Time value of money with any compounding.
Open tool → LiveSimple Interest
I = PRT — plus solve for any variable.
Open tool → LiveCommission Calculator
Turn sale amounts and rates into per-sale and total commissions.
Open tool → LiveSales Tax / VAT / GST Calculator
Add or extract sales tax, VAT, or GST from any price in seconds.
Open tool → LiveDiscount / Percent-Off Calculator
Stack discounts and see exactly what you'll pay and save.
Open tool → LiveRetirement Savings Projector
Project your retirement nest egg year by year.
Open tool → LiveInvestment Return (ROI) Calculator
Profit, ROI %, and annualized return for any investment.
Open tool → LiveSalary / Take-Home Pay Calculator
Gross pay to take-home pay, with full deduction breakdown.
Open tool → LiveInflation Calculator
See what past dollars are worth today with CPI data.
Open tool → LiveFuel Cost & Road Trip Calculator
Fuel cost for any trip — split among travelers too.
Open tool → LiveElectricity Bill Estimator
Estimate your power bill by appliance, watt by watt.
Open tool →Related categories
More from the codex
Browse all categories
Every category on the codex, from study tools to ciphers — pick your starting point.
Browse → LivePrompt Simulator
Practice prompt engineering: write prompts, get scored 0–10.
Open tool → LiveGPA Calculator
Semester and cumulative GPA with weighted scales and a target planner.
Open tool →About these calculators
Every tool below is free, works in your browser, and needs no account.
- Are the financial calculations accurate?
- Yes — mortgage amortization, compound interest, and payoff schedules use the standard closed-form math, verified by automated tests.
- Why do some calculators ask for my location?
- They don't — but things like sales tax and take-home pay vary by jurisdiction, so those tools ask you to enter your own rates rather than guessing.
- Is there a calculator for [X]?
- Browse the list — with 31 calculators, it's probably here. If not, the search box on the homepage finds tools by keyword.
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