How to use the savings calculator
Enter your savings goal, what you have saved already, how many years you have and the APY your account pays. Pick how often you will save (weekly, every two weeks to match a biweekly paycheck, or monthly) and whether each deposit goes in at the start or end of the period. The calculator shows the deposit you need every period, how much you will put in, how much interest adds, and a year-by-year plan.
Already know what you can afford? Type it into "How long will it take?" to see when you will reach the goal at that pace. Everything runs in your browser, and nothing you type is sent anywhere.
How much do I need to save each month?
Without interest the answer is simple: subtract what you have from the goal and divide by the number of deposits. To get from $2,000 to $20,000 in 3 years with 36 monthly deposits, that is $18,000 ÷ 36 = $500.00 a month.
Interest lowers that. At a 4% APY your $2,000 grows to $2,249.73 by itself, and each deposit earns interest from the day it goes in, so you need only $465.38 a month. You deposit $16,753.84 in total and interest supplies the other $1,246.16. At the FDIC national average savings rate of 0.38% (FDIC National Rates and Rate Caps), the same goal takes $496.61 a month, because interest does almost none of the work.
More time helps far more than a higher rate. Stretching the same goal to 5 years drops the deposit to $265.44 a month, with $2,073.48 coming from interest.
The savings goal formula
Banks quote savings accounts as an annual percentage yield, which already includes compounding (CFPB: Regulation DD (Truth in Savings)). The calculator turns the APY into a rate per deposit period: i = (1 + APY)1/k − 1, where k is 12 for monthly, 26 for every two weeks or 52 for weekly. At 4% APY the monthly rate is 0.3274%.
With n deposits, your starting balance P grows to P(1 + i)n. A deposit D at the end of every period grows to D × [(1 + i)n − 1] ÷ i, the future value of an annuity. Set the two equal to your goal and solve for D: D = [Goal − P(1 + i)n] × i ÷ [(1 + i)n − 1]. Deposits at the start of each period earn one extra period of interest, so the formula is divided by (1 + i). When deposits rise each year, the calculator works it out deposit by deposit instead.
For a feel for how interest builds on interest over long periods, the SEC's Investor.gov (SEC): compound interest calculator shows the same idea for investments.
Weekly, biweekly or monthly?
Saving more often barely changes the total, but it can make the goal easier to fit into your budget. For the $20,000 example, you need $107.26 a week, $214.60 every two weeks or $465.38 a month. Weekly deposits add up to about $464.80 a month, a little less than monthly saving because each dollar starts earning sooner. Putting each deposit in at the start of the month instead of the end saves only $1.52 a month.
The CFPB suggests making saving a habit with a specific amount each day, week or payday, and calls automatic recurring transfers one of the easiest ways to do it (CFPB: An essential guide to building an emergency fund). Match the frequency here to your paycheck and set up the transfer for the day you get paid.
Raising your deposits every year
If you expect raises, you can start smaller and increase your deposit each year. Saving for $20,000 over 5 years, a flat deposit is $265.44 a month. If you raise it 5% every year, you can start at $241.11 a month and finish at $293.07 in year 5. The year-by-year table shows the deposit for each year.
How long will it take to save?
Turn the question around when you know your budget. Starting from zero, saving $150 every two weeks at a 4% APY builds a $10,000 emergency fund in 64 paychecks, about 2 years and 6 months, with $471.09 of that from interest. The CFPB notes that even a small emergency fund helps you recover faster from surprise expenses, and suggests putting part of a tax refund toward it to get started.
Where to keep money you are saving
For goals a few years away, an insured savings account, money market account or CD keeps your principal safe. Deposits at FDIC-insured banks are covered up to $250,000 per depositor, per insured bank, for each account ownership category (FDIC deposit insurance). To compare savings accounts, use the high-yield savings calculator; if you can lock money up until a set date, try the CD calculator. For goals decades away, see the retirement calculator.
Interest is taxable income in the year it is credited to an account you can withdraw from, and banks send Form 1099-INT when it reaches $10 or more (IRS Topic No. 403: Interest received). The calculator shows results before tax.
Updated November 1, 2026 · Sources are linked in the text above · How we build and check our calculators