Calculation approach
The calculators use standard formulas for compound growth, present and future value, amortization, cash flow and inflation. They keep full precision behind the scenes and round displayed amounts for readability, so a total may differ slightly from the sum of its rounded line items.
Results depend on user inputs and stated assumptions. They are estimates, not account statements, quotes, tax calculations, credit decisions or forecasts.
The investment growth, savings goal and time-to-goal calculators place recurring deposits at the beginning or end of each selected contribution period. Weekly and every-two-week schedules use 52 and 26 evenly spaced periods per year, not calendar dates. Planning horizons are rounded to whole months. A one-time deposit in month 0 is added today; other month numbers mean the end of that month.
Missing information is not zero
Required inputs must be completed before a result is shown. An optional cost left blank is excluded from the estimate, not looked up or assumed to be a verified zero. Enter costs that apply to you. Invalid numbers are flagged beside the field; the calculators do not infer a nearby state or substitute an outdated rule.
When you enter a net or after-tax amount, the calculator does not subtract the same tax again. Controls that mark an amount as already included prevent double-counting.
Planning shortcuts
The financial independence calculator estimates bridge spending in stages, allowing for income that starts or stops during the plan. The bridge is shown in today's dollars without investment growth during the bridge itself. The portfolio target uses the largest annual spending gap across those stages and your withdrawal-rate assumption. It is not a year-by-year withdrawal simulation.
Refinance break-even divides closing costs after lender credits, including financed costs and any entered prepayment penalty, by initial monthly payment savings. Cash applied to principal is tracked separately. This shortcut does not compare future equity or total wealth.
Where a period offers months or years, switching units keeps the same duration. Calculations that operate month by month round the period to whole months. Saved scenarios retain the underlying duration even when reopened in the default unit.
Federal and state rules
We only supply a federal value when it has a current effective year, an official source and a review record. State and local rules vary widely. Unless a specific, dated state rule is built in, you enter the relevant amount or effective rate.
The product does not infer a state from an IP address or browser location. Rule changes can occur after publication, so users should verify current requirements before acting.
Returns, fees, taxes and inflation
- Investment returns are scenarios and are never guaranteed.
- A return already stated after fees or taxes is not reduced by the same item again.
- Nominal and real dollars are labeled and inflation is applied once.
- Tax treatment is modeled only from an explicit rule or user-supplied effective assumption.
- Cash flow and economic cost are separated when loan principal or asset value would otherwise be counted twice.
Editorial and source policy
Guides are published by the Editorial team. This identity does not imply professional certification. We prefer primary sources such as the IRS, SSA, CFPB, SEC, BLS, Department of Labor and official state agencies. Secondary research is used only when it directly supports a clearly labeled concept that an official source does not address.
A publication date records the first public edition. A modified date is added when a documented content or source change materially affects the guide. Each guide links to sources that readers can inspect directly.
Testing and limitations
Testing covers formulas, edge cases, validation, keyboard use, responsive layout and representative browser flows. Some results are compared with independent calculations or official examples. Tests can reveal defects but cannot certify suitability for a particular person or guarantee that an external source remains current.
Material corrections are prioritized. A time-sensitive rule that cannot be verified should be disabled in favor of manual input.
Questions and corrections
To report a possible error, include the calculator, non-sensitive inputs, expected result and source you used. Do not send account numbers, tax documents, passwords or other sensitive records through the contact form.