Interest Rate Converter
✓ Link copiedTranslate an interest rate or investment return from one time period to every other, with the compounding done correctly. Type a rate into any of the four boxes — daily, weekly, monthly, or annual — and the other three recalculate as you type. Unlike naive multiplication, the converter compounds the rate: a 1% daily return is not 7% a week but (1.01)⁷ − 1 ≈ 7.2135%, and over a 365-day year it snowballs to roughly 3,678%. That makes the tool ideal for sanity-checking trading strategies ("what does 0.5% a day really mean per year?"), comparing savings products quoted over different periods, annualizing a weekly portfolio result, or breaking an annual percentage yield down into its daily equivalent. Negative rates work too, so you can see how a small daily loss compounds into a painful annual one. Everything runs entirely in your browser — nothing you type is uploaded — so it is private, instant, and works offline.
Type a rate in any box and the other periods update instantly. Conversions compound: 1 week = 7 days, 1 month = 365 ÷ 12 days, 1 year = 365 days — so a 1% daily return is (1.01)⁷ − 1 ≈ 7.2135% weekly, not 7%.
How to use
Enter a percentage rate in whichever box matches the period you know — for example, type 1 into the Daily box for a 1% daily return. The weekly, monthly, and annual boxes fill in immediately with the compounded equivalents, and each box has a copy button. To convert the other way, just type into a different box: whichever field you edited last becomes the source and the rest are derived from it. Rates can be negative (a loss) down to -100%. The note under the fields spells out the conversion assumptions: 7 days per week, 365 ÷ 12 days per month, and 365 days per year.
Frequently asked questions
- Why is a 1% daily return not 7% weekly and 365% annually?
- Because returns compound: each day's gain earns its own return on every following day. Growing by 1% a day for 7 days multiplies your money by 1.01 seven times — (1.01)⁷ ≈ 1.0721, a 7.2135% weekly return. Over 365 days the same 1% compounds to (1.01)³⁶⁵ − 1 ≈ 3,678%, roughly ten times what the naive 365% guess suggests. The gap between the simple sum and the compounded result grows dramatically with the rate and the number of periods.
- What assumptions does the converter make about period lengths?
- The day is the base unit: a week is exactly 7 days, a month is 365 ÷ 12 ≈ 30.42 days, and a year is 365 days. Defining the month this way keeps everything self-consistent — twelve compounded months equal exactly one year, and converting daily → monthly → annual gives the same answer as daily → annual directly. Real calendar months vary between 28 and 31 days, so treat the monthly figure as a uniform average rather than a calendar-specific one.
- Can I use it for losses or for bank interest rates?
- Yes. Enter a negative percentage to model a loss — a 1% daily loss compounds to about a 6.79% weekly loss and a 97.4% annual loss, which is exactly why consistent small losses are so destructive. Rates below -100% are rejected, since you cannot lose more than everything per period. For bank products, note this tool converts compound (effective) rates like APY; a quoted nominal APR that banks divide across periods without compounding is a different convention, so check how your rate is quoted. All calculations happen locally in your browser and nothing is sent to a server.