Compound interest
See how a starting amount, regular deposits, and time could grow your money.
Saving & investingBIG IDEAS. LITTLE CALCULATORS.
Serious math.
A little
horseplay.
Make sense of your money without a finance degree. Free calculators, plain-English answers, and just the right amount of horsing around.
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Small steps.
Long strides.↘
Long strides.↘
THE COMPOUND EFFECT TRY IT
5,000 to start. 200 added monthly.
$124,379
A little consistency goes a long way.
You put in$53,000
Modeled growth$71,379
Give it time
Illustration: USD, 7% nominal annual rate, monthly compounding, end-of-month deposits. No fees or tax. Not a forecast.
Put in your own numbersCHIEF OATS
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PICK YOUR WORKHORSE
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18 calculators. Zero spreadsheets required.
Savings goal
Work backward from a goal to the monthly amount that could get you there.
Saving & investingLoan & extra payments
Estimate loan payments and see what extra repayments could save in time and interest.
Everyday moneyInflation & buying power
Estimate future prices and how inflation can nibble away at the money you hold.
Economics 101Depreciation
Compare straight-line and accelerated depreciation, with a year-by-year book value schedule.
Business basicsMargin & markup
Find your profit, margin, and markup—or work out the price needed for a target margin.
Business basicsBreak-even point
Find how many units cover your costs, and how many could hit your profit goal.
Business basicsPercentage toolkit
Calculate a percentage, compare two numbers, or increase and decrease an amount.
Everyday moneyDiscount & sales tax
Stack two discounts, add a tax rate, and see the final price and actual saving.
Everyday moneyAnnualized growth (CAGR)
Turn a start and end value into a smoothed annual growth rate.
Saving & investingReturn on investment
Calculate the total return on an investment, including additional costs and income received.
Saving & investingThe little-spend calculator
See what a recurring expense adds up to—and what the same money could grow into.
Saving & investingEmergency fund
Set your own savings cushion and see the gap, coverage, and time needed to build it.
Everyday moneySalary converter
Convert an hourly rate or annual salary into annual, monthly, weekly, and hourly equivalents.
Everyday moneyUnit price showdown
Compare two packs fairly—even when their sizes are different.
Everyday moneyRule of 72
Compare the famous quick estimate with the exact constant-rate doubling time.
Saving & investingReal return
Adjust a nominal return for fees and inflation to estimate a change in buying power.
Economics 101Price elasticity
Measure how quantity responds to a price change using the midpoint method.
Economics 101No horses in this paddock.
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A MOMENT OF HORSE SENSE
Big numbers.
Small print that actually helps.
Every calculator shows its working, explains its assumptions, and tells you what the answer means. Because a number without context is just a very confident guess.
How we do the math01 / THE MONEY MYTH“A 50% markup means
“A 50% markup means
a 50% profit margin.”
Nope. Buy for 40. Sell for 60.
That’s 50% markup, but 33.33% margin.
Same profit. Different denominator.
Your numbers stay yours.
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Aha, not alphabet soup.
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