SmartFin

Runs one amount through three ways of buying the same US stock or index ETF over a chosen period, on real daily closing prices (adjusted for splits and reinvested dividends): all at once on the first trading day (lump sum), spread evenly on the trading day nearest the 1st of each month, or bought after the price falls a set % from its latest high. Returns each strategy's final value, total and yea

What an amount invested in a US stock or index ETF became over a past period under one strategy: lump_sum (all on the first trading day), monthly (spread on the trading day nearest the 1st of each month) or buy_the_dip (bought after falls of a set % from the latest high), on real daily closing prices (adjusted for splits and reinvested dividends). Returns final value, total and yearly return, wors

What a fixed amount in a US stock or index ETF became across reference periods ending today (or on as_of_date): since 2000, since the dot-com peak (24 Mar 2000), since the dot-com crash low (9 Oct 2002), since the 2007 peak (9 Oct 2007), since the 2008 crash low (9 Mar 2009), since 2010, since the COVID low (23 Mar 2020), since the 2022 low (12 Oct 2022), and the last 10, 5 and 1 years. Each row g

Monthly payment, total interest and total paid for a fixed-rate loan with monthly payments: mortgage, car, student or personal loan. Give either loan_amount, or home_price with down_payment_pct for a mortgage. Use when the user asks what a loan costs per month or in total, or how the rate or term changes the cost. Do not use for variable-rate loans, interest-only loans, or credit cards. Excludes t

Future balance of savings or an investment growing at a fixed yearly rate, with optional monthly contributions and a chosen compounding frequency. Returns the balance, total paid in and interest earned. Use for forward-looking "how much will I have" questions at an assumed rate. Do not use for what a real stock did in the past (use smartfin_calculate_investment_return). A fixed rate is an assumpti

What an amount will be worth in today's money after years of inflation at a fixed yearly rate, and what something costing that amount today will cost then. Use for questions about buying power or future prices at an assumed inflation rate. Do not use for historical CPI lookups: this uses one fixed rate, not official index data.

Works the way SmartFin's FIRE calculator does. The FIRE number today is yearly expenses divided by a withdrawal-rate assumption. Each year savings grow at an assumed return with the yearly savings added, while expenses (and so the FIRE number) rise with inflation; FIRE is the first year savings reach that year's FIRE number, searched up to 60 years. Also gives the savings rate and, with a traditio

Works the way SmartFin's withdrawal calculator does, with withdrawals monthly, quarterly or annually and the balance earning a yearly return between them. how_long: how many years a balance lasts at a set withdrawal, optionally rising each year with inflation. how_much: the withdrawal that lasts a given number of years, or that never touches the principal (lasts_forever). Use for "how long will my

The interest earned and the final amount on a principal at a fixed yearly rate over a number of years, when interest is not compounded (interest = principal x rate x time). Use for questions about simple interest on a loan or deposit, such as a short-term note or a bond coupon at a flat rate. Do not use when interest is added back to the balance (use smartfin_calculate_future_value or smartfin_pro

What a single present amount grows to at a fixed yearly rate with interest added to the balance at a chosen frequency, and the growth over the starting amount (FV = PV x (1 + r/n)^(n x t)). Use for questions about what a lump sum becomes after some years at an assumed rate, or the effect of compounding more often. Do not use for regular contributions (use smartfin_project_savings_growth), for what

Finds the one missing number among four that sit in the same equation, a single amount earning one fixed yearly rate with interest added at a chosen frequency (FV = PV x (1 + r/n)^(n x t)): the future value, the starting amount, the annual rate, or the time in years. Use when the user knows three of the four and wants the fourth, e.g. "what rate turns $10,000 into $20,000 in 10 years", "how many y

What an amount due in the future is worth today at a fixed yearly discount rate, and the discount between the two (PV = FV / (1 + r/n)^(n x t)). Use for questions about the value today of money received later, at a discount rate the user supplies. Do not use to pick a discount rate (the tool has none of its own), for several payments over time, or for a market price: it discounts one amount at one

The profit or loss and the ROI percentage from an initial investment and a final value (ROI = (final - initial) / initial x 100). Negative results are valid. It is not annualized. Use for questions about the total percentage return on money put in, from two values. Do not use for a return per year (use the CAGR calculator at smartfin.fyi/cagr-calculator.html), for what a real stock returned (use s

The profit and the profit margin percentage from revenue and total costs (margin = (revenue - costs) / revenue x 100). A negative margin is a valid result. Use for questions about profit as a share of sales, from two figures for the same period. Do not use for return on money invested (use smartfin_calculate_roi), for taxes, or to say whether a margin is good: the tool reports the figure only. The

Compares buying a home with a fixed-rate mortgage against renting a similar home and investing the money not spent on the home, over the years someone plans to stay, the way SmartFin's rent vs buy calculator does. Both start with the same cash and spend the same each month; whichever costs less that month invests the difference. Returns the modeled money each choice leaves (home sold and loan paid

Compares the modeled balances of a savings account and of an investment after 1 to 50 years, from the same starting amount and the same monthly contribution, the way SmartFin's savings vs investing calculator does. You give the savings rate and the investment return; each is held the same every year. Optional: a yearly increase in the monthly contribution (or one that follows inflation), a yearly

The HTML to put one of SmartFin's free calculators on a website the user runs: a blog post, a class or library page, a client resources page. One iframe line, free, no sign-up, no cookies or tracking; the widget fills the width it's given and follows the reader's light or dark mode. Calculators: investment (Investment growth calculator), compound_interest (Compound interest calculator), mortgage (