Savings Calculator

Each month the balance earns interest and your deposit is added on top: balance = balance × (1 + i) + deposit where i is the monthly rate derived from the APY. A $1,000 start with $200 a month at 4% APY for 5 years grows to about $14,400 — of which roughly $1,400 is interest the balance earned on its own, not money you deposited.

A savings account paying close to 0% and one paying 4–5% APY look like a small difference over a single month, but the gap compounds — each month's extra interest itself earns interest in every month that follows, so the advantage widens the longer the money sits. Over five or ten years, the difference between a near-zero rate and a competitive one can add up to a meaningful fraction of the total balance, entirely from a number that looked small at the outset. It is also worth checking whether a quoted rate is an introductory rate — some accounts advertise an attractive APY for a limited window before it drops to a lower ongoing rate, which changes the real long-run growth this calculator projects using a single constant rate.

In the early months, the deposits themselves are what drive the balance up — interest on a small starting amount is small. Over years, that flips: interest earned on the accumulated balance starts contributing more than any single new deposit. That is why a steady, automated monthly deposit — even a modest one, kept up consistently — tends to build a larger balance over time than waiting to accumulate a big lump sum before starting. The calculator holds the monthly deposit constant, so raising it, or starting it sooner, both compound in the same way the rate does.

APY is already the honest, compounded figure — unlike a bare nominal rate, it reflects how often interest is actually credited, so comparing accounts by APY (not by an advertised nominal rate) compares them fairly. What APY does not reflect is what happens to the money after it is earned: interest in a regular savings account is generally taxable income in the year it is credited, reported to you and the IRS on Form 1099-INT, whether or not you withdraw it. It also does not adjust for inflation — a dollar figure the calculator shows as growth reflects nominal dollars, and part of that nominal growth is only keeping pace with rising prices rather than adding real purchasing power.

This is a projection built on the rate, deposit and time you enter held constant — real savings accounts have variable APYs that change with broader interest rate conditions, so an account paying today's rate will not necessarily pay the same rate for the entire period you are projecting. Deposits held at a federally insured bank or credit union are protected up to the current FDIC or NCUA insurance limit per depositor, per institution — a real and useful protection, but a separate question from what rate the money earns. This calculator answers the growth question; whether a given account is insured, and what its rate will do beyond today, are worth confirming directly with the institution.