# Fixed APY
Annual Percentage Yield is abbreviated as **APY**. This calculates the real rate of return on your principal investment after compounding interest is applied. In Quanterra, your $QUANT represents your principal, and compound interest is calculated on a periodic basis (every 15 minutes), referred to as a 'Epoch'.
Your new principal amount is equal to the sum of your then-current $QUANT and your newly rebase token amount. This total is used to calculate your subsequent rebase rewards.
**Compound Interest's Magnificence** - It's critical to remember that your balance will grow exponentially over time, not linearly. Using a compound interest rate of 0.02355 percent / 15 minutes, the following calculation is made:
**EXAMPLE 1****: If you began the year with a balance of only 1 $QUANT, after a year, your balance will have increased to 3829.45 $QUANT**.
**EXAMPLE 2****: If you began with a $1,000 balance on day 1, after a year, your balance will have increased to $3,830,454**.
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