250 a month for five years
Starting from 1 000 and saving 250 a month at 3%, the balance after five years is about 17 320.
You will have deposited 15 000 of that. The interest — roughly 1 320 — is what the plan earned while you were not looking.
Savings calculator
Three questions, one calculator: what your savings become, what you need to put aside to hit a goal, and how long that goal will take. Pick the question, and the form adapts.
This is a projection based on a constant rate. Real savings rates change, often at the bank’s discretion.
Result
Fill in the fields to see your result.
How it works
Saving with interest is two things happening at once. The amount you already have grows on its own, compounding period after period. The deposits you add form a second stream, each one earning interest for the time that remains. The calculator works them out separately and adds them — which is also why the results panel shows them separately.
The three modes solve the same equation for a different unknown. Ask what you will have, and it solves for the final balance. Ask what to put aside, and it solves for the deposit. Ask how long, and it solves for the number of periods — a logarithm, which is why the answer rarely lands on a whole month.
Deposit frequency matters more than most people expect, but not in the way they think. Saving 1 200 a year as twelve deposits of 100 beats one deposit of 1 200, because the early deposits earn for longer. The gain is real but modest: at 3%, roughly 1.4% more over a year.
Formulas used
Future value of a savings plan
F = P × (1 + i)^n + C × ((1 + i)^n − 1) ÷ i
- P
- amount already saved
- C
- deposit each period
- i
- interest rate per period
- n
- number of deposits
Multiply the second term by (1 + i) for deposits made at the start of each period.
Deposit needed to reach a goal
C = (F − P × (1 + i)^n) × i ÷ ((1 + i)^n − 1)
- F
- savings goal
- P
- amount already saved
- i
- interest rate per period
- n
- number of deposits
The same equation, rearranged for C instead of F.
Worked examples
A 25 000 goal in five years
The same 1 000 head start grows to 1 162 on its own, leaving about 23 840 to come from deposits.
That works out at just under 369 a month. Stretch the same goal to seven years and the monthly figure drops to around 254.
How long at 250 a month?
Keeping the deposit at 250 instead of raising it, the same 25 000 goal takes about seven years and one month.
That is 86 deposits, 21 500 of your own money and roughly 2 690 in interest.
Assumptions and limits
- The interest rate stays the same for the whole period.
- Every deposit is made, in full and on time.
- Interest is left in the account and never withdrawn.
- No account fees, tax or penalties are applied.
Frequently asked questions
What interest rate should I enter?
Use the rate your account actually pays, not the headline rate on the advert. Promotional rates usually expire after a few months and fall back to a much lower one.
For a long plan, entering a rate slightly below what you are offered gives you a projection you are unlikely to be disappointed by.
Is it better to save weekly or monthly?
Weekly wins, but barely. The same yearly total split into weekly deposits earns a little more because each deposit starts working sooner — at 3% the difference is a fraction of a percent over a year.
Pick the rhythm you will actually keep to. Consistency is worth far more than the frequency.
Why is the time never a round number of months?
Solving for time takes a logarithm, and the answer lands wherever it lands — 85.4 periods, for instance. Since you cannot make four tenths of a deposit, the calculator rounds up to the first whole deposit that carries the balance past your goal.
That is why the balance reached is usually a little above the target.
Does this include tax and inflation?
Interest is shown before tax. If your account is taxable, enter the rate after tax to get a realistic figure.
Inflation is optional: fill it in and the panel adds what the final balance would be worth in today’s money. A 3% return with 3% inflation leaves you exactly where you started in real terms.
Updated
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