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Free calculators that run entirely in your browser
Danfio builds focused tools for the money and file problems people hit every week: mortgage and loan payments, debt payoff plans, mortgage affordability, pay and tax estimates, then file, text and developer utilities. Each page explains the maths it uses, so you can check the answer instead of trusting a black box.
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Every calculator documents the formula and the assumptions behind it, with worked examples generated by the same engine that powers the tool.
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Calculators, downloaded schedules and copy-ready results are free. The site is funded by display advertising, never by selling your data.
Loans & Mortgages
Payments, amortization, refinancing and what you can afford.
Airbnb Profit CalculatorWork out what a short-term rental earns after the platform fee, the lodging tax, the cleaning costs and the fixed costs of the property, with a break-even occupancy.Open calculator →Amortization Schedule CalculatorGenerate a full amortization schedule for any loan: every payment split into interest and principal, with yearly totals and a CSV export.Open calculator →APR CalculatorTurn a loan offer into its APR: add origination fees and points to see the real annual percentage rate beside the advertised interest rate.Open calculator →Auto Loan CalculatorCalculate your car payment from the vehicle price, trade-in, sales tax, fees and APR. See total interest, the payoff date and the full schedule.Open calculator →Closing Cost CalculatorAdd up lender fees, points, title, appraisal, recording and escrow prepaids, then see the total as a share of the price and the cash you bring to closing.Open calculator →Home Affordability CalculatorFind the maximum home price that fits your income, debts and down payment using the 28/36 debt-to-income rules, including tax, insurance and HOA.Open calculator →Lease vs Buy Car CalculatorPrice a lease and a purchase over the same months, including the money factor, the sales tax, the loan balance at the end and the resale value that decides the answer.Open calculator →Loan CalculatorWork out the monthly payment, total interest and full amortization schedule for any fixed-rate loan. Free, instant and computed in your browser.Open calculator →Mortgage CalculatorFree mortgage calculator with property tax, insurance, HOA and PMI. See your monthly payment, total interest and a full amortization schedule instantly.Open calculator →Mortgage Payoff CalculatorSee how much time and interest extra payments save on a mortgage or loan. Enter an extra monthly or annual amount and get the new payoff date instantly.Open calculator →Moving Cost CalculatorPrice the same move three ways: a full-service mover, a container you pack and a truck you drive, with the distance at which the cheapest option changes.Open calculator →Personal Loan CalculatorWork out the monthly payment on a personal loan, the true APR once origination fees are counted, and how much extra payments shorten the term.Open calculator →Property Tax CalculatorTurn a market value into a property tax bill through the assessment ratio, exemptions and the mill rate, and see what a reassessment or another county would cost.Open calculator →Realtor Commission CalculatorWork out the commission on each side of a sale, what the seller pays in concessions and closing costs, and the money that actually reaches them.Open calculator →Refinance CalculatorCompare your current loan with a refinance offer: new payment, monthly saving, break-even point on closing costs and lifetime interest saved.Open calculator →Rental Property CalculatorNet operating income, cap rate, cash-on-cash return, debt coverage, the one percent rule and depreciation, from the rent, the costs and the mortgage.Open calculator →Student Loan CalculatorCalculate the monthly payment on a student loan, compare 10, 15, 20 and 25-year terms, and see what paying a little extra every month saves.Open calculator →Student Loan Refinance CalculatorCompare your student loan with a refinance offer: monthly saving, lifetime interest, the break-even point on the fees and the true cost of a longer term.Open calculator →
Debt & Credit
Payoff plans, interest cost and credit card minimums.
Credit Card Payoff CalculatorSee how long a credit card balance takes to clear on minimum payments, and how much interest and time a fixed extra payment saves you.Open calculator →Debt Consolidation CalculatorCompare keeping your cards and loans against one consolidation loan on the same monthly budget: interest saved, payoff time and when the fee is recovered.Open calculator →Debt Payoff CalculatorCompare the debt snowball and avalanche methods on your real balances. See your debt-free date, total interest and the order each debt gets cleared.Open calculator →Debt-to-Income CalculatorWork out your debt-to-income ratio the way a lender does, see the room left before the 43% limit, and test a new loan before you apply.Open calculator →
Income & Payroll
Take-home pay, hourly rates, overtime and raises.
Overtime CalculatorWork out weekly pay with overtime at time and a half, double time or a custom multiplier, and see the premium that those hours add over the year.Open calculator →Pay Raise CalculatorSee what a pay raise is worth per paycheck and per year after federal income tax and FICA, and whether it actually keeps up with inflation.Open calculator →Paycheck CalculatorEstimate your take-home pay from a salary with 2026 federal tax brackets, FICA, state tax and pre-tax deductions, shown per paycheck and per year.Open calculator →Payroll Tax CalculatorWork out the employer share of Social Security and Medicare, FUTA and state unemployment on top of wages, and the fully loaded cost of an employee.Open calculator →Salary to Hourly CalculatorConvert a salary into an hourly rate or an hourly rate into annual pay, including the paid leave that makes the two numbers different.Open calculator →
Business & Freelance
Invoicing, quoting, billable hours and the cost of running a business.
Estimate GeneratorBuild a quote from materials, labour, contingency, overhead and markup, see the margin, and split the total into a deposit and progress payments.Open calculator →Freelance Rate CalculatorWork out the hourly, day and monthly rate a freelance business needs, including tax, expenses, unpaid admin hours and unpaid days off.Open calculator →Invoice GeneratorCreate an invoice with line items, discounts, tax, deposits and late fees, then print it or save it as a PDF. Nothing is uploaded.Open calculator →LLC Cost CalculatorWork out what an LLC costs: state filing fee, annual report, registered agent, accounting and insurance, in year one and every year after.Open calculator →Timesheet CalculatorTurn daily hours into weekly pay with the 40-hour overtime rule, a daily overtime rule for states that use one, punch rounding and billable time.Open calculator →
Taxes
Income tax, sales tax, capital gains and after-tax returns.
Capital Gains Tax CalculatorWork out capital gains tax for 2026: the 0%, 15% and 20% ladder, what a short-term gain costs instead, and the 3.8% net investment income tax.Open calculator →Income Tax CalculatorSee federal income tax bracket by bracket for 2026, plus FICA and state tax, and what a raise really adds to your tax bill.Open calculator →Sales Tax CalculatorAdd state, county, city and district sales tax to a price, or work out how much tax is hidden inside a total you already paid.Open calculator →Self-Employment Tax CalculatorWork out self-employment tax the way Schedule SE does: 92.35% of profit at 15.3%, the deductible half, the QBI deduction and quarterly payments.Open calculator →VAT CalculatorAdd VAT to a net price, take VAT out of a gross price, and check second-hand sales under the margin scheme at any rate.Open calculator →
Investing & Savings
Compound growth, retirement targets and savings goals.
401(k) CalculatorSee what your deferral and your employer match add up to, which 2026 limit applies at your age, and what the balance becomes by retirement.Open calculator →Average Down CalculatorSee what buying more at a lower price does to your average cost, the price you need to break even, and how to size the position from the risk you accept.Open calculator →Compound Interest CalculatorSee how a lump sum and regular deposits compound over time, what the effective annual rate really is, and the deposit needed to reach a goal.Open calculator →Crypto DCA CalculatorAdd each crypto purchase, see the average cost it produces, what the position is worth today, and how it compares with a single lump-sum buy.Open calculator →Crypto Profit CalculatorWork out the profit or loss on a crypto trade after the exchange fees on both sides, network costs and tax, plus the price you need just to break even.Open calculator →Dividend CalculatorSee what a shareholding pays in dividends, what reinvesting them buys over time, and how the income grows when the dividend itself rises each year.Open calculator →Retirement CalculatorProject your retirement balance from monthly saving, work out the nest egg your spending needs, and see how long the money lasts once withdrawals start.Open calculator →ROI CalculatorWork out the return on an investment, the annualised rate behind it, and how the same position looks at a different exit price. Includes fees and dividends.Open calculator →Roth vs Traditional CalculatorCompare a Roth and a traditional account after tax, find the break-even tax rate, and see what the same money does in a taxable brokerage account.Open calculator →
Insurance & Benefits
Life, auto and home insurance needs plus benefit trade-offs.
ACA Subsidy CalculatorWork out the 2026 premium tax credit from household income, household size and the benchmark silver premium, including the return of the 400% poverty line cliff.Open calculator →Health Insurance Deductible CalculatorCompare two health plans on premium, deductible, coinsurance and out-of-pocket maximum, and see the level of medical spending at which the cheaper plan changes.Open calculator →Life Insurance CalculatorAdd up the income, mortgage, debt and education a household depends on, net off savings and existing cover, and see what term cover costs against a cash-value policy.Open calculator →
PDF & Documents
Merge, split, compress and convert files without uploading them.
Add Page Numbers to PDF (and Crop)Add page numbers to a PDF in your browser: pick the corner, the wording such as "Page 3 of 12", the starting number, and trim the margins while you are there. No upload.Open calculator →Compress PDFShrink a PDF in your browser by re-encoding the pictures inside it: choose a JPEG quality and a pixel width cap, keep the text selectable, and download the smaller file.Open calculator →JPG to PDFTurn JPG and PNG pictures into one PDF in your browser: one image per page, A4 or Letter sheets, Exif rotation applied so phone photos arrive upright. No upload, no watermark.Open calculator →Merge PDFMerge PDF files in your browser: drag two or more PDFs in, keep every page in order and download one combined file. No upload, no account, no watermark.Open calculator →PDF to WordConvert a PDF to an editable Word .docx in your browser: the text layer of every page is written into a real Word file, with a page break per page. No upload, no sign-up.Open calculator →Rotate / Organize PDF PagesReorder and rotate PDF pages in your browser: type a new order like 3, 1, 2, flip the whole document or turn selected pages. No upload, no account, no watermark.Open calculator →Sign PDFFill a PDF form and add a signature in the browser: the fields the document already has, plus a signature picture or a typed name. No upload, no account - and honestly, not a digital signature.Open calculator →Split PDFSplit a PDF in your browser: pull page ranges out into separate files or one file, or cut the document every N pages. No upload, no account, no watermark.Open calculator →Unlock PDFRemove the password from a PDF you can already open: qpdf decrypts it in your browser, and the unlocked copy is read back and checked before you download it.Open calculator →Watermark PDFAdd a text watermark to a PDF in your browser: choose the words, the angle, the colour and the opacity, and every page is marked on your own device. No upload, no sign-up.Open calculator →
Everyday & Health
Dates, units, BMI and the small maths of daily life.