Savings Plan Calculator
Use this savings plan calculator to project how your savings will grow over time, or to work backwards from a target amount and discover exactly how much you need to set aside each week, month, or year. Enter an initial deposit, a regular contribution, an interest rate, and a time horizon. Switch to Goal mode and the calculator solves for the required periodic contribution automatically. Results update instantly and include a full year-by-year breakdown.
How savings compound over time
Compound interest means your interest earns interest. In the first year you earn interest on your initial deposit. In the second year you earn interest on that deposit plus last year's interest, plus whatever you added. Over long horizons the effect is dramatic: at 5% APY compounded monthly, a single $10,000 deposit becomes about $16,470 in 10 years and $26,533 in 20 years, without adding a single extra dollar. The key variable is the Annual Percentage Yield (APY), which is the nominal rate adjusted for compounding frequency. Daily compounding at 5% gives an APY of about 5.127%; monthly compounding gives 5.116%. The difference is small in the short term but adds up over decades.
Forward mode vs. Goal mode
This calculator works in two directions. Forward mode answers the question: "If I save X per month at Y% for Z years, what will I have?" Goal mode flips the question: "I need $50,000 in 5 years - how much do I need to save each month?" Both modes use the same compound interest engine; the goal solver uses a binary search to find the contribution amount that exactly reaches your target. In goal mode the calculator also shows you the breakdown between contributions and interest, so you can see how much of the work the interest is doing for you.
The effect of contribution frequency and annual increases
Saving weekly instead of monthly is not just about discipline: it earns slightly more interest because your money enters the account sooner within each month. On a 20-year savings plan at 5%, switching from annual to monthly contributions can add several hundred to a few thousand dollars to the final balance. The annual increase feature lets you model a realistic scenario where your contribution rises each year, perhaps to match inflation or salary increases. A 3% annual increase is a common rule of thumb. This can meaningfully close the gap between what a flat contribution would accumulate and what you actually need.
Tax and after-tax savings strategies
In a taxable brokerage or savings account, the interest you earn is generally taxable in the year it is credited. A 20% tax rate on a 5% return effectively reduces your yield to 4%. Over 20 years, that gap compounds significantly. Tax-advantaged accounts eliminate or defer that drag: Roth IRAs and Roth 401(k)s grow tax-free; traditional IRAs and 401(k)s defer tax until withdrawal. In the UK, an ISA wrapper protects all growth from income and capital gains tax. If you are choosing between a taxable HYSA and a tax-advantaged account, the tax savings are often more valuable than a slightly higher headline rate.
High-yield savings rate benchmarks (2024-2025)
| Account type | Typical APY range | Best suited for |
|---|---|---|
| Traditional savings account | 0.01% - 0.50% | Emergency fund, short-term goals |
| High-yield savings account (HYSA) | 3.50% - 5.25% | Emergency fund, 1-3 year goals |
| Money market account | 3.00% - 5.00% | Emergency fund, flexible access |
| 6-month CD | 3.50% - 5.20% | Short-term fixed goals |
| 1-year CD | 3.50% - 5.30% | Known 1-year expenses |
| 5-year CD | 2.50% - 4.00% | Longer fixed-term goals |
| I Bonds (US) | Inflation-linked (2-5% range) | Inflation protection, 1+ year hold |
| Index fund (historical average) | ~7% real / ~10% nominal | Retirement, 10+ year horizon |
Typical APY ranges from FDIC-insured accounts and low-risk vehicles. Rates change frequently.
Frequently asked questions
What is the savings plan calculator used for?
It projects the future value of a savings account that grows through compound interest and regular contributions. You can also run it in reverse: enter a savings goal and time horizon, and it tells you how much you need to deposit each week, month, or year to reach that target.
What does compounding frequency mean?
Compounding frequency is how often interest is calculated and added to your balance. If interest compounds monthly, interest earned in January is added to the February starting balance so it earns interest in February too. Daily compounding does this 365 times a year. The more often interest compounds, the slightly higher your effective annual yield (APY) will be compared to the stated nominal rate.
How is APY different from the interest rate I was quoted?
The interest rate you are quoted is the nominal or annual rate. APY (Annual Percentage Yield) accounts for the effect of compounding within the year. For example, a 5% nominal rate compounded monthly gives an APY of about 5.116%. Banks in the US are required to disclose APY so you can compare accounts fairly. This calculator shows you the APY alongside the nominal rate you enter.
Should I include a tax rate?
If your savings are in a regular taxable account, enter your marginal income tax rate on interest. In the US, savings account interest is taxed as ordinary income, so someone in the 22% bracket would enter 22. If you are using a Roth IRA, 401(k), ISA, or other tax-sheltered account, leave the tax rate at 0, because interest in those accounts grows tax-free or tax-deferred.
What is a realistic interest rate to use?
For cash savings, high-yield savings accounts and money market accounts were offering 4-5% APY in 2024-2025. CDs typically range from 3.5 to 5.3% depending on term. For long-term goals in an investment account, many financial planners use 6-7% real (after inflation) or about 8-10% nominal for a diversified stock index fund, based on historical averages. Using a conservative rate leads to a healthier savings buffer.
What is the annual contribution increase feature?
It lets you model a growing contribution. If you set it to 3%, your contribution increases by 3% every year. For example, if you start saving $200 a month and apply a 3% annual increase, by year 5 you are saving about $231 a month. This is useful if you expect your income to rise and want to see a more realistic projection than a flat contribution assumption.
How does the Goal mode solve for the required contribution?
Goal mode uses a binary search algorithm. It tests a contribution amount, runs the full compound-interest simulation, checks whether the final balance meets your target, and adjusts the contribution up or down until the result converges to within a cent. This approach handles compounding frequency, tax, and annual contribution increases exactly, rather than using an approximation formula.