Personal finance starts with knowing four numbers: what you own, what you owe, what you bring in, and what you spend. Most of the rest of financial planning is downstream of those four. Our personal finance calculators are organized around making those numbers concrete and showing how decisions today affect them over time.

The budget calculator gives you a structured monthly view using the 50/30/20 framework (50% needs, 30% wants, 20% savings and debt) as a starting baseline. The debt-to-income (DTI) calculator computes the ratio lenders use to qualify you for mortgages and loans — most lenders want DTI under 43% for conforming mortgages and prefer it under 36%. The cost of living calculator compares city-to-city pay equivalents so a $80k offer in Atlanta can be compared apples-to-apples with a $120k offer in San Francisco.

For life-event planning, dedicated calculators address pay raise impact (including bracket creep), inflation-adjusted salary needs over time, wedding budgets, student budgets for college years, and side-hustle income projections. The life expectancy calculator uses CDC actuarial tables to estimate how long retirement savings need to last — a particularly important input for the retirement category's safe-withdrawal calculations.

Currency conversion is included for international travel and remote work, using current exchange-rate references that update against the European Central Bank reference rates.

Where we use national averages (cost-of-living indices, average inflation rates, life expectancy), data sources are: BLS Consumer Price Index for inflation; BEA Regional Price Parities for cost-of-living comparisons; CDC NCHS life tables for life expectancy. Currency rates are reference-only — your actual exchange rate at a bank or card transaction will include a 1-3% spread above the reference rate. None of these calculators replace a relationship with a fee-only fiduciary financial planner for major life decisions.