How the monthly amount is worked out
Your goal is reached by two things: what you already have growing with interest, and the monthly deposits (plus the interest they earn). The calculator first works out what your current savings will grow to, then finds the deposit that covers the gap.
gap = goal − current × (1 + r)n
monthly deposit = gap × r ÷ ((1 + r)n − 1)
- r is the monthly interest rate: yearly rate ÷ 12 ÷ 100.
- n is the number of months.
With 0% interest, it's simply the gap divided by the number of months.
Worked example
You want 20,000 in 5 years, you have 2,000 now, and your savings account pays 4.5%.
Your 2,000 grows to about 2,503.59 on its own. That leaves a gap of 17,496.41.
Monthly deposit = 260.57. Over 60 months you put in 17,634.46 in total (including the 2,000), and interest adds the remaining 2,365.54.
How interest changes what you need to save
The same goal (20,000 in 5 years, starting from 2,000) at different rates:
| Interest rate | Save each month |
|---|---|
| 0% (cash) | 300.00 |
| 2% | 282.17 |
| 4.5% | 260.57 |
| 7% | 239.75 |
Over short periods, interest helps a little. Over 10 years or more it does much more of the work, which is why starting early matters more than the exact rate.
Tips for hitting a savings goal
- Automate it. Set up an automatic transfer on payday so the money moves before you can spend it.
- Use a separate account. Keeping the goal apart from everyday money makes it easier to leave alone, and you can see your progress.
- Choose where to keep it by deadline. For money you need within a few years, a high-interest savings account or fixed deposit is usually safer than stocks, which can fall just before you need the cash.
- Add windfalls. Putting part of a bonus or tax refund toward the goal can shorten the time a lot.
Good to know: this assumes a steady interest rate, monthly compounding, and a deposit at the end of every month. Real rates change, and interest may be taxed. It doesn't account for inflation, so a goal several years away may need to be a little higher to buy the same things. See the inflation calculator.
Frequently asked questions
What if I already have enough?
If your current savings will grow past the goal by the deadline, the monthly amount shows 0 and the calculator tells you the goal is reached on its own.
How big should an emergency fund be?
A common guideline is 3 to 6 months of essential expenses: rent, food, bills and debt payments. If your income is irregular, aim for the higher end.
Can I save weekly instead?
Yes. Multiply the monthly amount by 12 and divide by 52 for an approximate weekly figure. For 260.57 a month, that's about 60.13 a week.
Last reviewed November 2026.