Quick summary
Inputs come from the user
A result is only as sound as the rates, fees, dates and costs entered into the calculator.
Formulas show their limits
Each tool explains what it includes and what the general estimate cannot reproduce.
The signed document controls
A calculator can test a scenario, but the final contract, disclosure or policy sets the real obligation.
Loan calculations
Fixed-rate payment uses the standard amortization formula. Monthly rate is annual rate divided by twelve for illustration; actual disclosures may calculate finance charges differently. Total cost adds entered upfront fees to scheduled payments.
Affordability calculations
The stress test subtracts proposed housing costs, essential spending, maintenance and the user’s safety buffer from take-home income. It is a cash-flow screen, not a debt-to-income underwriting result.
Break-even calculations
Simple break-even divides incremental upfront or claim cost by periodic savings. Mortgage points compare the entered upfront points with principal-and-interest savings; PMI and deductible results likewise omit uncertain investment returns and claim frequency.
Payoff and ownership-cost calculations
The extra-payment tool simulates monthly interest and principal until payoff. Car total cost adds financing and entered running costs, then subtracts estimated vehicle value.
Lease-versus-buy compares cash out over one time period and subtracts estimated purchase equity. Taxes, opportunity cost and unentered charges remain outside the result.
Rounding and privacy
Currency results are rounded to the nearest dollar for planning. Calculations run in the browser; entries are not submitted or stored by BEFORE.YOU.
Input validation and edge cases
Tools treat blank or negative number entries as zero. They show estimates, not transaction quotes. Zero-interest loans use straight-line principal repayment.
Date tools use calendar days unless the page says to confirm another rule. Run the tool again whenever an offer, term, rate, fee or timeline changes.
How calculations are checked
Each calculator in the complete tools collection has a defined result area. We test page access, metadata, related guidance and stated limits. Formula changes get syntax and route checks before release.
A lender, insurer, tax agency or contract may use timing and definitions that a general tool cannot copy. The calculator methodology makes that boundary clear.