Savings goal calculator

1. It turns your timeframe into months and your yearly return into a monthly rate, the yearly rate divided by 12.
2. It finds the monthly deposit that, added at the end of each month and left to grow, lands exactly on your target.
3. It also works out the single amount you could put away today instead, under the same return.
4. It splits the target into what you deposit and what growth adds, year by year.

Both reach the same goal. A lump sum needs less money in total because all of it starts growing on day one. Monthly saving needs more in total but spreads it out.

Over short periods, not much: it trims about $20 a month off the $10,000 goal. Over long periods it does a lot. Saving $819.69 a month for 30 years at 7% reaches $1,000,000, and only $295,088.98 of that is your own money.

Because every dollar of a lump sum grows for the full time, while monthly deposits made near the deadline barely grow at all. The lump sum figure is the target worked backward at your return, a step called discounting.

Check the default. Put $9,050.25 away today at 5% a year, and after 24 months of growth it reaches $10,000. Saving monthly instead takes 24 deposits of $397.05, or $9,529.13 in total, because the later deposits have little time to earn anything. The gap of about $479 is the price of spreading the money out.

A smaller goal shows the same pattern. To reach $5,000 in one year at 4%, you could save about $409.08 a month or put about $4,804.27 away today. Neither choice is better in general. If you already have the cash, the lump sum is cheaper. If you are saving from each paycheck, the monthly figure is the one to automate.

Match the return to where the money will sit. For money you need within a few years, use what your savings account or Treasury bills actually pay, because a fall in the stock market right before your deadline could leave you short. A higher assumed return adds uncertainty; it is not a promise, even for a long goal. The input is a nominal annual rate divided by 12. To convert an advertised APY to this input, use 12 × ((1 + APY/100)^(1/12) − 1) × 100. Taxes and fees are not deducted.

Insured savings accounts and short Treasury bills are the usual choices. Bank deposits are covered by the FDIC, and accounts at federally insured credit unions are covered up to $250,000 by the NCUA.⁴

Treasury bills are loans to the U.S. government that mature in 4, 6, 8, 13, 17, 26 or 52 weeks. You buy them for less than face value, in $100 steps, and receive the full face value at maturity; the difference is your interest.³ A goal exactly one year away fits neatly into a 52 week bill bought at the start.

The catch is that rates change. A savings account rate can drop next month, and a bill that matures has to be reinvested at whatever the new rate is. So for a multi year goal, enter a return a little below today’s rate. If the net return exceeds your assumption and deposits stay on schedule, you may finish early.

For short goals, safety comes first. FDIC bank coverage and NCUA credit-union coverage generally protect up to $250,000 per depositor or member, per insured institution, for each ownership category.¹ Stocks suit goals that are many years away, because they can fall sharply in any single year.

The calculator uses nominal dollars and does not raise your target for inflation. If your goal is a price, such as a car or a down payment, it may cost more by the time you get there. The inflation calculator shows how much more.

• Automate it. Set a transfer for the day after payday, so the money moves before you can spend it.
• Keep goals separate. One account per goal makes progress easy to see.
• Check in yearly. This tool starts from zero: grow your existing balance to the deadline at the same assumed rate, subtract that future value from the target, and calculate the monthly amount needed for the remainder.

Grow the target by expected inflation before you enter it. Inflation is usually measured with the Consumer Price Index, which tracks the average change in prices paid by urban consumers.⁶

Say a car costs $30,000 today and you plan to buy in three years. If prices rise 3% a year, multiply by 1.03 three times: the car costs about $32,782 by then. At a 4% return, reaching $30,000 takes $785.72 a month, but reaching $32,782 takes about $858.58. Skip the adjustment and you arrive roughly $2,800 short.

For goals only a year or two away, the difference is small. For a college fund 18 years out, it can be large, so redo the math once a year with a fresh price and your real balance. A simple habit is to check the current price of what you are saving for, raise the target if it has climbed, and let the calculator reset the monthly amount. Small yearly corrections are far easier than one large catch up near the deadline.