WebToolArcAPY vs nominal interest rate
Annual percentage yield is an effective annual return that includes intra-year compounding. For a nominal annual rate r compounded n times per year, the standard mathematical conversion is APY = (1 + r/n)n − 1. Continuous compounding uses er − 1.
Why recurring deposits are modeled separately
APY describes the account’s annualized yield; your deposits determine how many dollars are exposed to that yield. This Studio therefore reports principal, recurring contributions, interest and ending balance as separate quantities and lets you choose beginning- or end-of-period deposit timing.
Compare accounts without hiding fees and bonuses inside APY
Three-scenario comparison applies each entered APY to the same savings plan, then shows user-entered monthly fees and one-time bonuses as separate dollar adjustments. A promotional bonus or fee is not silently relabeled as the institution’s advertised APY.
Regulation DD arithmetic is a separate evidence layer
CFPB Regulation DD Appendix A annualizes the relationship between interest, principal or average daily balance, and actual days in the relevant term or statement period. Tiered, stepped and product-specific rules can change the interest figure that belongs in that formula, so this page provides a cross-check rather than a compliance determination.
Variable APYs and real purchasing power
The growth projection holds the entered APY constant. The optional tax and inflation fields are planning assumptions only; actual tax treatment and future inflation can differ, and variable-rate savings products can change at any time.