About Passbion

Who runs Passbion

Passbion was founded and is run by Md Sabbir Ahamed. Questions and corrections reach the founder directly through the contact page.

Why we exist

A mortgage, a car loan or a stack of credit card balances can cost tens of thousands of dollars in interest, yet most online calculators return a single number with no explanation. You can't see the formula, the assumptions or how the figure was rounded, so you can't tell whether to trust it.

Passbion takes the opposite approach. Every calculator publishes the exact equation it uses, labels each input with its symbol in that equation, walks through a worked example with real numbers, and lets you download the full month-by-month or year-by-year schedule as a CSV file.

What we offer

• Mortgage Amortization Calculator: Monthly payment with taxes, insurance and PMI, plus a full amortization schedule.
• Assumable Mortgage Calculator: Assuming a seller's low-rate FHA or VA loan vs. a new loan: equity gap, blended rate, fees and interest saved.
• DSCR Loan Calculator: Net operating income, debt service coverage ratio and the rent a lender needs to see.
• Hard Money Loan Calculator: Loan size from ARV and cost, cash to close, interest on rehab draws and the flip's net profit and ROI.
• Seller Financing Calculator: Owner financing payments on a long amortization, the balloon due, the seller's interest and the IRS minimum rate.
• FHA Self-Sufficiency Test Calculator: The FHA rent test for 3–4 units, with mortgage insurance, reserves and what your own unit costs you.
• Rental Property Capital Gains Tax Calculator: Gain, depreciation recapture, capital gains tax and the 3.8% NIIT on a rental sale, and what a 1031 exchange defers.
• Rental Property Depreciation Calculator: The 27.5- or 39-year depreciation schedule from the IRS tables, with the land split, improvements and a sale.
• 1031 Exchange Calculator: Realized, recognized and deferred gain, cash and mortgage boot, the replacement's basis and the 45- and 180-day deadlines.
• Section 121 Exclusion Calculator: The 2-out-of-5-year tests, depreciation and nonqualified use taken out, the $250,000 or $500,000 limit and the tax on the rest.
• Auto Loan Early Payoff Calculator: Interest and months saved with extra payments, plus a refinance savings estimate.
• Debt Snowball vs. Avalanche Calculator: Side-by-side payoff plans, debt-free dates and total interest for both methods.
• Compound Interest Calculator: Growth with regular contributions, any compounding frequency and an inflation view.
• High-Yield Savings Calculator: Interest earned at your APY, compared with a regular savings account and a CD.
• T-Bill vs CD Calculator: A bill's investment rate from its discount rate, federal tax only on the bill, federal and state tax on the CD, and the tax-equivalent CD yield.
• 1099 Tax Calculator: Self-employment, federal and state income tax on 1099 income, with quarterly estimated payments for every state.
• 1099 vs W-2 Calculator: Employee FICA against self-employment tax, income tax on both, the value of benefits, and the hourly 1099 rate that matches a salary.
• S Corp Tax Savings Calculator: Self-employment tax on the whole profit against payroll tax on a reasonable salary, the QBI deduction both ways, and the S corp's running costs.

How we build and check each calculator

Our calculations use exact decimal arithmetic rather than ordinary floating-point math, so results don't drift by fractions of a cent. Loan schedules round each month's interest to the cent the way lenders do, and the final payment absorbs any leftover cents so balances end at exactly zero.

Each formula is covered by automated tests whose expected values come from a separate, independent implementation and from published reference figures, such as the standard payment on a $300,000, 30-year loan at 6.5%. The worked examples in our articles are generated by the same code as the calculators, so the text and the tool can never disagree. Our editorial guidelines describe the full process, including how we choose sources and handle corrections.

Your privacy

The calculators run entirely in your browser. The balances, rates and other figures you enter are never sent to our servers, and you don't need an account. See our privacy policy for details, including how advertising cookies work.

How the site is funded

Passbion is free to use and supported by advertising. Ads are clearly labeled and kept separate from calculator results and editorial content. Advertisers have no say in our formulas, examples or recommendations, and we don't rank or recommend specific lenders, banks or card issuers.

What we are not

We are not a lender, bank, broker or financial adviser, and nothing on this site is personalized financial, tax or legal advice. Our tools help you understand and compare options. Before you sign anything, confirm the rate, fees and terms with the provider, and consider speaking with a qualified professional about your situation.

Get in touch

Found an error, or want a calculator we don't have yet? Contact us or email hello@passbion.com.