A goal is a date plus a number
Saving without a target usually produces a balance that is whatever it happens to be when the money is needed. A savings goal reverses that: you name the amount and the date first, and the arithmetic then tells you the monthly saving the plan actually requires. This calculator works in both directions. In monthly mode you give it a goal, what you have already saved, a rate and a number of years, and it returns the exact monthly amount to set aside. In time mode you give it the monthly amount you know you can afford, and it counts the months until that habit, plus growth, reaches the goal. Either way, money you have already saved is not treated as static: it grows for the whole term first, and only the remaining gap has to be covered by new deposits. The general growth view is on the Savings Calculator; this page is the goal-first version of the same mathematics.
The savings goal formula
Gap = goal − FVcurrent · Monthly needed = gap × r ÷ ((1 + r)n − 1)
Where r is the monthly rate (yearly rate ÷ 12 ÷ 100) and n is the number of months. If the rate is zero, the monthly amount is simply the gap divided by the months. In time mode there is no closed-form shortcut used — the balance is grown month by month, with the deposit added at each month end, until it first reaches the goal, with a cap of 1,200 months.
Why your head start is worth more than it looks
The already-saved amount does quiet, outsized work. Because it is invested for the entire term, every dollar of it earns growth for every single month of the plan — unlike the monthly deposits, which arrive gradually and each earn growth only for the months remaining after they land. In the default example, $5,000 already saved at 5% over eight years grows to about $7,452.93 on its own: nearly $2,453 of the $50,000 goal is covered before the first new deposit is made, and the monthly requirement falls accordingly. This is the mathematical reason starting a goal with any lump sum — a bonus, a tax refund, the proceeds of selling something — beats starting the same goal from zero with a slightly larger monthly amount. The head start compounds for the longest possible time.
Worked example
Goal: $50,000 in 8 years. Already saved: $5,000, growing at 5% a year with monthly compounding at the monthly rate. Step one: the $5,000 grows over 96 months to about $7,452.93. Step two: the gap is $50,000 − $7,452.93 = about $42,547.07. Step three: the level monthly deposit whose own growth fills exactly that gap over 96 months is about $361.36. Check the intuition — 96 deposits of $361.36 total about $34,691 of your own money, and the remaining roughly $7,856 of the gap is covered by growth on the deposits themselves, the earliest deposits earning the most. Save the same amount with no head start and the monthly requirement would be noticeably higher; give the plan two more years and it falls sharply, because the deposits get more months of growth and the head start compounds for longer.
Choosing a rate you can defend
The rate field is where savings plans quietly become fantasies. Money in an insured savings account earns the account's actual rate — modest, but genuinely predictable. Money invested may earn more on average, with down periods along the way and no guarantee for a specific finish date, which matters when the goal has a hard deadline such as a house deposit or a school start. A sound habit is to run the calculator at two rates: the one you hope for, which sets the optimistic monthly figure, and a lower one you are confident of, which sets the figure to actually budget. If the goal only works at the hopeful rate, the plan — not the arithmetic — needs adjusting: a later date, a larger deposit, or a smaller target.
Worked example
To reach $50,000 in 8 years with $5,000 already saved at 5%: the saved amount grows to about $7,452.93, leaving a gap of about $42,547.07, which a monthly saving of about $361.36 covers exactly — roughly $34,691 from your deposits and the rest from growth.
How to use this calculator
- Choose the direction: monthly mode if you know the date and need the amount; time mode if you know the amount you can save and need the date.
- Enter the goal and what you have already saved toward it.
- Enter a yearly rate you can defend — your savings account rate, or a cautious return if the money is invested.
- In monthly mode enter the years available; in time mode enter the fixed monthly amount instead.
- Budget the figure from a cautious-rate run, and revisit the plan whenever the rate, the goal or the date changes.
When the answer is more than you can save
Sometimes the calculator's honest answer is a monthly amount your budget cannot carry, and that is useful information rather than a failure — it arrives years before the deadline does. The formula leaves exactly four levers. Save for longer, which helps twice: more deposits, and more growth on each one. Find a larger starting amount, which compounds for the full term. Aim the goal at a smaller target, or split it into stages — a first milestone you can reach, then a second plan from a stronger starting position. Or raise the monthly amount gradually, increasing it with each pay rise; a deposit that grows each year reaches a goal sooner than the level figure suggests, so treat the level answer as the ceiling of what you need, not the only path.
Goals compete — rank them
Most households run several goals at once — an emergency fund, a holiday, a deposit, a car — and a single monthly surplus has to be divided among them. The emergency fund usually deserves first claim, because it protects all the others from being raided when life interrupts; goals with fixed external deadlines come next, because their dates cannot move; flexible goals take what remains. Running each goal through this calculator separately, then adding the monthly figures, shows whether the combined plan fits the surplus. If it does not, the ranking — not wishful thinking — decides which date moves.