# Annual Percentage Yield APY stands for Annual Percentage Yield. This measures the real rate of return on your principal tokens amount by taking into account the effect of compounding interest. In the case of Forever Safu, your $4SAFU tokens represent your principal, and the compound interest is added periodically on every Rebase event (Every 10 minutes). Your new principal amount is your then current 4SAFU token amount, plus your new rebase token amount. This total amount is what gets calculated for your next rebase rewards. One interesting fact about APY is that your balance will grow not linearly but exponentially over time! Assuming a daily compound interest of 2.488%, if you start with a balance of 1 $4SAFU on day 1, after a year, your balance will grow to about 6819.8080 $4SAFU. That is the power of compound interest! ![](https://4127744435-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FghBB5dxVecfP9869GXaP%2Fuploads%2FsaNHqwwpcgVImbEpKhCL%2FPage%205-1.png?alt=media\&token=c7dcd277-5ea5-40e1-ade6-004937e39532) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://foreversafu.gitbook.io/forever-safu/annual-percentage-yield.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.