Guide

How a savings goal payment is set

Published August 17, 2026

A savings-goal payment is what the deposits still have to supply, divided by the annuity factor. Reaching $30,000 in 5 years at 4 percent compounded monthly takes $452.50 a month. You pay in $27,149.74 and interest supplies $2,850.26.

Monthly deposit

$452.50

60 deposits reach $30,000 in 5 years.

Paid in over the term: $27,149.74
Interest earned: $2,850.26
Balance at the deadline: $30,000.00

Target amount

Years to the deadline

Annual rate

Already saved

Compounded and paid in

Deposits land at the end of each period, which is what a standing order does.

In short

Reaching $30,000 in 5 years at 4 percent compounded monthly, from a standing start, takes $452.50 a month. You pay in $27,149.74. Interest supplies $2,850.26.
Start with $5,000 already saved and the same target, rate and horizon. The head start grows to $6,104.98. The monthly deposit falls to $360.41.
Give the standing start three more years instead of a head start: 8 years to $30,000 at the same 4 percent is $265.68 a month. Time cuts the deposit more than a $5,000 head start did.
Short goals are mostly saving. On the five-year sheet, interest is a little under a tenth of the target. The deposit, not the rate, is doing the work.
The formula assumes a constant rate and a deposit at the end of every month. Missed months are not averaged in later. They are a smaller target or a longer wait.

What the deposits still have to supply

A savings goal is a future-value problem run backwards. You know the target. You know the rate. You want the deposit.

Grow whatever is already saved to the end date. Subtract that from the target. What is left is what the deposits still have to supply. Divide by the annuity factor for the rate and the number of deposits, and you have the payment.

On $30,000 in 5 years at 4 percent compounded monthly, with nothing saved yet, that payment is $452.50. Over 60 months you pay in $27,149.74. Interest supplies $2,850.26, a little under a tenth of the target.

The savings goal calculator on this page is that division. Compound interest is the engine underneath. Present value is the same arithmetic facing the other way.

An emergency fund is one use of this page: a target built from months of essentials, then a deposit that reaches it on a date you pick.

The deposit this page names has to land somewhere. Savings account types is which wrapper that somewhere is, and why a rate quoted on a locked term is not the same object as a rate you can spend next week.

The forward identity of that same stream is how annuity future value works: the payment in, the rate, the years, and the total on the last day, split into money paid in and interest.

A head start cuts the deposit

Keep the $30,000, the 5 years and the 4 percent. Start with $5,000 already saved. That $5,000 grows to $6,104.98 by the end date, so the deposits only have to supply the rest. The monthly figure falls to $360.41. You pay in $21,624.78. Interest, counting growth on the head start and on the deposits, is $3,375.22.

The head start works twice: it is money you do not have to save, and it compounds for the whole horizon. That is why $5,000 already in the account is worth more than five thousand extra dollars paid in later.

Time cuts it more

Back to a standing start. Give the same $30,000 eight years instead of five, still at 4 percent monthly. The deposit is $265.68 a month. You pay in $25,505.11. Interest supplies $4,494.89.

Three extra years cut the deposit by more than the $5,000 head start did ($452.50 down to $265.68, against $452.50 down to $360.41). On a short goal, time is the lever that moves the monthly figure most, because each extra year both spreads the saving and gives interest more periods to work.

The rate still matters. It matters more the longer the wait. On a five-year sheet, most of the $30,000 is money you put in.

A five-year target funded at 4 percent is mostly money you put in. That is saving. Saving against investing is when the same monthly figure is instead aiming at a return that can go backwards, and why those two jobs do not share a pot without a reason.

What this page is not doing

It is not a forecast of 4 percent, not a sinking fund with irregular deposits, and not a claim that $452.50 is the right amount for a household. The three sheets are $30,000 in 5 years from zero, the same target with $5,000 already saved, and $30,000 in 8 years from zero. This is educational material, not financial advice.

Worked examples

Reaching \$30,000 in 5 years from a standing start

You want $30,000 in 5 years. The account pays 4 percent compounded monthly and you have nothing saved yet. What goes in each month?

Find the period rate: $r/n = 0.04/12$ , a third of a percent a month. Carry it as the fraction, not as a rounded decimal, because the next step but one divides by it and so multiplies any rounding error by 300.
Count the deposits: $nt = 12 \times 5 = 60$ .
Build the growth factor: $(1 + 0.04/12)^{60} = 1.220996594$ .
Turn it into the annuity factor: $\frac{1.220996594 - 1}{0.04/12} = 66.298978$ .
Nothing is saved yet, so the deposits supply the whole target: $30000 / 66.298978 = 452.49566$ , which is $452.50 a month.
Add up what you pay in: $452.49566 \times 60 =$ $27,149.74.
The target minus the deposits is the interest: $30,000 less $27,149.74 is $2,850.26.

You need $452.50 a month. Over the 5 years you pay in $27,149.74 and interest supplies $2,850.26, which is a little under a tenth of the target. Short goals are mostly saving, not mostly earning.

The same target with \$5,000 already saved

Same $30,000 target, same 5 years at 4 percent compounded monthly, but there is already $5,000 in the account. What is the deposit now?

Grow the head start to the deadline first: $5000 \times 1.220996594 = 6104.98297$ , or $6,104.98.
That is what the $5,000 is worth on the day you need the money.
Take it off the target: $30000 - 6104.98297 = 23895.01703$ , which is what the deposits have to supply. Subtract the unrounded figure: rounding the head start to the cent here moves the total paid in by enough to change it.
The annuity factor is unchanged at 66.298978, because the rate and the term have not changed.
Divide: $23895.01703 / 66.298978 = 360.41305$ , which is $360.41 a month.
Total deposits: $360.41305 \times 60 =$ $21,624.78.
Interest is the rest: $30,000 less $21,624.78 less the $5,000 you started with is $3,375.22.

The deposit falls to $360.41, roughly a fifth less. The head start does two jobs: $5,000 of the target is covered on day one, and it grows to $6,104.98 by the deadline, so it covers more than its own face value. Interest now supplies $3,375.22 rather than $2,850.26.

Three more years instead of a head start

Same $30,000 at the same 4 percent compounded monthly with nothing saved, but you give yourself 8 years rather than 5. What does the extra time do?

The period rate is the same $0.04/12$ , but now $nt = 12 \times 8 = 96$ .
Growth factor: $(1 + 0.04/12)^{96} = 1.376395119$ .
Annuity factor: $\frac{1.376395119 - 1}{0.04/12} = 112.918536$ .
Divide the target by it: $30000 / 112.918536 = 265.67826$ , which is $265.68 a month.
What you pay in: $265.67826 \times 96 =$ $25,505.11.
Interest supplies the rest: $30,000 less $25,505.11 is $4,494.89.

$265.68 a month, against $452.50 for the same target in 5 years. Three extra years cut the deposit by about 41 percent, and interest now supplies $4,494.89 instead of $2,850.26. A better rate cannot compete with that over a short horizon: interest was supplying $2,850.26 of the $30,000, under a tenth of the goal, and a higher rate acts only on that tenth. Time acts on the count of deposits itself.

Common questions

Why is the five-year goal mostly saving, not earning?

Because five years is a short compounding window. On the first sheet, interest is $2,850.26 of a $30,000 target, a little under a tenth. The $452.50 deposit is doing the work. Stretch the wait to 8 years and interest's share rises, but the deposits still supply most of the target.

Does already-saved money just subtract from the target?

No. It grows. $5,000 already saved becomes $6,104.98 over 5 years at 4 percent monthly, so the deposits have to supply less than the full $30,000. Subtracting $5,000 from $30,000 and then solving would overstate the deposit.

What if I skip a month?

The formula assumes a deposit at the end of every month. A skipped month is not made up by averaging later. Recalculate with a smaller remaining target, a longer wait, or a larger deposit from here.

Keep reading

This page is educational material, not financial advice. The figures come from the formula shown and assume the inputs you enter hold for the whole term. Your own rate, fees, taxes and timing will differ, so treat the output as arithmetic to check a decision against, not as a recommendation.