How much do I need to save each month to hit my goal?

A savings goal is an annuity solved backwards. The forward version is the one every calculator does: put in $5,000, add $639 a month, run it at 4% for 3 years, see what comes out. You can watch that happen on the compound interest calculator with these exact inputs. What you actually want is the other direction, and it is one line of algebra away: rearrange the same equation for the payment and you get PMT = (FV - PV(1 + i)^n) * i / ((1 + i)^n - 1).

Read it in three pieces and it stops looking like a formula. PV(1 + i)^n is what you already have, left alone: $5,000 becomes $5,636 in 3 years without you doing anything. FV minus that is the gap your contributions have to close, $24,364. The last factor, i / ((1 + i)^n - 1), converts a lump sum at the deadline into the level monthly payment that builds it, and it is smaller than one over n because the early payments have time to earn as well. Here it turns $24,364 of gap into $638 a month: $22,972 of money you put in and $2,028 the account added, which is 6.8% of the final total.

Standing transfers are set in whole dollars, so the honest number to automate is $639, which lands at $30,034 rather than exactly $30,000. If the return turns out to be 0%, and for money you need on a fixed date that is not a silly thing to plan for, the formula collapses to the gap divided by the months: $694. The whole contribution of a 4% return over 3 years is the $56 a month between those two figures.

Every field on the calculator changes the answer. Only one changes it by multiples. Cut the runway from 5 years to 1 year and the same $30,000 goes from $360 a month to $2,029, roughly 5.6 times as much, while the return you assume is worth $56 a month across that entire 3 years. Waiting six months to start is not a small decision you can make up later. Here, halving the runway to 1 year and 6 months raises the payment from $638 to $1,333.

The table below is the same arithmetic from a standing start, nothing saved yet, at a 4% return. Read across a row for the cost of a shorter deadline; read down a column for what a bigger goal costs on the same one.

Notice the rows are almost exactly proportional: doubling the goal doubles the payment, because the formula is linear in FV. The columns are not. $25,000 in 1 year is $2,045 a month, and in 5 years it is $377, which is less than a fifth as much for five times the runway rather than one fifth exactly, because the contributions in the longer plan are themselves earning. That gap is the entire argument for starting a goal you cannot yet fully fund.

A required contribution is only useful if you can make it. When you cannot, the number that matters is the date. The same equation solves for n instead of PMT, n = ln((FV + PMT/i) / (PV + PMT/i)) / ln(1 + i), and the calculator runs both at once: the payment your deadline demands, and the deadline your payment produces.

On the default inputs those two answers disagree, which is the normal case. The deadline wants $638 a month. Saving $500 instead gets you to $24,727 by month 36, $5,273 short, and $30,000 arrives in 3 years and 9 months rather than 3 years. Being $138 a month behind costs 9 months, and that is the trade to make with your eyes open: move the date, move the goal, or find the difference. Two of those three are usually easier than the one people reach for first.

Where the difference comes from matters more than the calculator can see. If you are carrying a balance at a double-digit rate, the arithmetic is not close: paying it down is a guaranteed return at that rate, and this page assumes 4%. Price that side first on the debt payoff calculator, and treat the savings goal as what happens after. The one goal that legitimately jumps the queue is a cash buffer, because the whole point of it is to stop the next surprise from becoming more debt. That one has its own page: the emergency fund calculator sizes it from what your months actually cost rather than from a round number.

Sometimes the required contribution is zero, and a calculator that returns a negative payment or a divide-by-zero has failed you at exactly the useful moment. If what you have saved grows past the goal on its own before the date, this page says so and tells you when. Take $28,000 saved against a $30,000 goal 5 years out at 4%: the required contribution is $0, because $28,000 alone reaches $30,000 in 1 year and 9 months and holds $34,188 by the deadline.

That is a real answer, not a null. It tells you the goal is funded and that anything you add from here buys time rather than the goal itself, which is usually the cue to point new money at the next thing. It also raises the question this calculator will not answer for you: whether money you do not need for 5 years should be sitting where a 4% assumption is the right one at all. A goal with a date is a different instrument from a goal without one, and the second kind is the FIRE number: no deadline, just a balance large enough to replace an income. If the goal in the box above is a house deposit, the number that actually constrains you is not the deposit but the payment it unlocks, which is the house affordability question.

Tax on the interest. In a taxable account the interest and dividends are income in the year you receive them, so the rate that compounds for you is the after-tax rate, and this page has no idea what yours is. The fix is to type the return you expect to keep rather than the return you expect to earn: keeping 75% of 4% means entering 3%, which moves the required contribution from $638 to $652 a month. Inside a Roth IRA, a 401(k) or an HSA there is nothing to adjust.

That the return happens at all. 4% here is a fixed number applied to every month identically, which is not how any real account behaves. Cash and short Treasuries come close over a horizon this short, and their rate moves. Anything with equity in it does not come close: the average can be right and the path can still leave you short on the exact month you need the money, which is the one risk a savings goal with a date cannot absorb. The shorter and harder the deadline, the more the assumed return should look like something you can actually be sure of, and the more of the work the contribution should be doing.

What the thing will cost. The goal is taken exactly as typed and nothing here indexes it. If prices on it rise 3% a year, which is an assumption you are choosing rather than a fact this page knows, then $30,000 today is $32,782 on the date, and the contribution that buys it is $711 rather than $638 a month. Also absent: fees, which come out of the return; employer matching, which is a contribution you did not make; withdrawals along the way; any month you skip; and any account limit or early withdrawal penalty. Nothing here is investment advice.

This calculator is built to be used without a browser. Every input is a query parameter on this page, and the same parameters on the JSON twin return the complete answer as a document.

GET /tools/savings-goal.json?goal=40000&saved=8000&months=36&contribution=600

The response carries inputs after parsing and clamping, result with requiredMonthly, the contribution that lands on the goal, to the cent, and requiredMonthlyRounded, the whole dollar a standing transfer would be set to, with endBalanceRounded showing where that lands; alreadyFunded and fundedInMonths for the case where the starting balance clears the goal on its own; savedGrown, gap, growthFactor and monthlyRate, the four intermediate terms of the closed form; the inverse answer as yourMonths, yourMonthsExact, yourBalance, yourGap and yourMonthsDelta; horizons, the same goal priced at one, three and five years; yearly, the balance schedule; plus drivers and sensitivity across the rate and the horizon, drivers ranked by effect with a plain sentence each, assumptions that say for every field whether you supplied it and name the source when the default came from one, sources with a URL and an as-of date for each source the tool cites, which is an empty list on the calculators whose every default is an example input rather than a published figure, warnings, a disclaimer, and in tool the canonicalUrl and jsonUrl that carry only your non-default parameters. The canonical URL is the answer's permanent address; use it when you cite the number.

Parameters, all optional, in any order:

• goal ($), default $30,000.
• saved ($), default $5,000.
• months (months), default 36 months.
• contribution ($ per month), default $500 per month.
• rate (%), default 4%.

Values accept plain numbers and loose human formats such as 100k, $100,000, or 6.5%. Unknown parameters are ignored, values outside a field's range are clamped and reported in warnings, and the endpoint never fails on bad input. Responses are cacheable for a day; the defaults change when their sources publish, and tool.version changes when the method does.

This calculator cites no external source, on purpose. Every default is an example input: the goal, the balance, the deadline and the contribution are placeholders to replace with your own, and the return is an assumption you choose rather than a statistic anybody publishes about your money. The arithmetic itself is the standard annuity relation stated above, solved once for the payment and once for the time. The two illustrative fractions used in the copy, keeping 75% of the interest after tax and prices rising 3% a year, are labelled as assumptions where they appear and are not claims about your situation; every figure derived from them is computed by the same module the calculator runs.

Carlo is a personal finance agent. It knows your accounts, debts, and goals, so instead of one goal at an assumed rate it can see what you are actually setting aside each month, tell you which goals that pace really funds and by when, and say what has to give when a month goes badly. Text it the question.

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