Savings Calculator

This savings calculator (also called a savings account calculator, saving calculator, or savings interest calculator) projects what your money grows to with regular deposits and compound interest. It doubles as a HYSA calculator for high-yield savings accounts, a CD calculator for certificates of deposit, and a savings bond calculator when you plug in Treasury bond rates. All inputs are editable, so you can compare a 4.5% HYSA against a 5.0% CD in seconds.

1. Initial Deposit: how much you are starting with today. For a CD, this is your lump sum. For a new HYSA, it is your opening transfer.
2. Monthly Deposit: how much you add each month. Set this to $0 for a one-time deposit (for example, a CD or savings bond that does not allow additions after opening).
3. Annual Interest Rate (APY): find this on your account disclosure or CD offer. Traditional savings accounts pay 0.01% to 0.5% APY. High-yield savings accounts at online banks run 4% to 5% APY. 12-month CDs are in a similar 4% to 5.5% range, depending on the rate environment.
4. Savings Period: how many years you plan to leave the money. For a CD, use the term length (6 months, 1 year, 5 years). For a HYSA, use your target horizon.

The output shows your final balance, the total you deposited, and the interest earned. The year-by-year table below the result is where compounding becomes visible: early years are mostly your own deposits, later years are mostly interest. If you see that the interest slice is small, either the rate or the time horizon is doing the heavy lifting, and one of them needs to go up for your savings plan to reach the goal.

FV = P(1 + r/n)^(nt) + PMT * [(1 + r/n)^(nt) - 1] / (r/n)

Where:
FV = Future value (final balance)
P = Initial deposit
PMT = Monthly contribution
r = Annual interest rate (decimal)
n = 12 (monthly compounding)
t = Time in years

Compound Interest on a Lump Sum

If you are not making monthly contributions (for example, a CD or savings bond held to maturity), the formula simplifies to the classic compound interest equation:

A = P(1 + r/n)^(nt)

Example: $10,000 CD at 5.0% APY for 3 years, monthly compounding
A = 10,000 × (1 + 0.05/12)^(12 × 3)
  = 10,000 × (1.004167)^36
  = 10,000 × 1.16147
  = $11,614.72

Daily compounding (n = 365) produces a slightly higher result than monthly compounding at the same APR, but APY already accounts for the compounding frequency, so when you are comparing two accounts by APY the numbers are directly comparable.

Contribution Frequency: Monthly vs Annual

Depositing the same annual total in 12 monthly installments beats a single year-end lump sum because the early deposits compound for longer. Depositing $200 at the start of each month for a year at 5% APY earns about $54 in interest. Depositing $2,400 in one shot at year-end earns $0 in that first year. Over 30 years the gap between monthly and annual contributions of the same size grows to several thousand dollars on a modest savings plan.

The Rule of 72 for Doubling Time

For a rough estimate of how long it takes money to double at a given rate, divide 72 by the rate: 72 ÷ 4.5 is about 16 years, so $10,000 in a 4.5% HYSA doubles to $20,000 in roughly 16 years with no contributions. At 6%, doubling takes 12 years. At 2%, it takes 36 years. The rule is accurate to within a few months for rates between 2% and 10% and works for any kind of compounding investment.

Quick Reference: $10,000 at 4.5% APY

With no monthly contributions, a $10,000 deposit at 4.5% APY compounded monthly grows like this:

Add a $200 monthly deposit to the same account and the 30-year balance jumps to roughly $190,400, of which about $118,400 is interest. The monthly contribution is doing most of the work past year 15.

The savings interest calculator above works for any fixed-rate product, but picking the right product matters as much as the math. Traditional savings, high-yield savings, money market accounts, CDs, and Treasury savings bonds all pay interest on cash, but they trade off rate, liquidity, and rate-lock in different ways. Use this section to match the account type to the goal.

Account Types Compared

Rates below reflect typical 2024-2025 ranges. Specific offers change monthly, so check current APYs before opening an account.

When a CD Beats a HYSA, and When It Does Not

A HYSA rate floats with the federal funds rate. When the Fed cuts rates, your HYSA APY drops within a few weeks. A CD locks in today's rate for the full term, so it wins when rates are about to fall and loses when rates are about to rise. In a flat or falling rate environment, a 12-month CD at 5.0% beats a HYSA at 4.5% that may be 4.0% in six months. In a rising rate environment, the HYSA adjusts up and the locked CD looks worse. The trade-off is liquidity: breaking a CD early usually costs 3 to 12 months of interest, depending on the term.

CD Laddering: Get Most of the Rate Without the Lockup

A CD ladder spreads one lump sum across multiple CD terms so part of the money matures every year. Split $25,000 five ways: a 1-year, 2-year, 3-year, 4-year, and 5-year CD at $5,000 each. When the 1-year matures, you either spend the cash or roll it into a new 5-year CD. After five years, you hold five 5-year CDs with one maturing every year. You get close to the long-term CD rate while always having cash coming free within 12 months, and you never have to guess which way rates are heading.

FDIC Insurance: $250,000 Per Depositor, Per Bank, Per Ownership Category

FDIC (and NCUA for credit unions) insures up to $250,000 per depositor, per insured bank, per ownership category. A single account holder at one bank is covered for $250,000 total across checking, savings, money market, and CDs combined. Add a joint account and the joint side has its own $250,000 cap per co-owner. Two spouses with individual accounts and a joint account at the same bank are covered for $1,000,000 ($250K each individual, $500K joint). Above those limits, spread the money across multiple FDIC-insured banks, or use a cash sweep program that splits deposits automatically. Treasury savings bonds are not FDIC-insured because they are direct federal debt, which is backed by the full faith and credit of the US government.

I-Bonds vs EE-Bonds: Two Very Different Tools

Series I savings bonds pay a composite rate that resets every six months: a fixed rate plus an inflation component tied to CPI. The fixed rate stays with the bond for its 30-year life, so an I-bond bought when the fixed rate is 1.0% keeps a 1.0% real-return floor for the full term. Purchase limit is $10,000 per person per year through TreasuryDirect, plus an extra $5,000 in paper bonds via a tax refund. You cannot redeem an I-bond in the first 12 months, and redeeming before 5 years forfeits the last 3 months of interest. Series EE savings bonds pay a low fixed rate but carry a federal guarantee that the bond will double in value if held for 20 years, giving an effective yield of about 3.5% regardless of the stated rate. Both bonds earn interest that is exempt from state and local tax, and can be federally tax-free if the proceeds pay for qualified higher-education expenses.