Year-by-year investment growth
Each bar is the balance at the end of that year, split across its three sources.
Detailed schedule
| Year | Opening balance | Deposits this year | Total deposits | Interest this year | Total interest | Closing balance |
|---|
Compound interest means your returns are calculated on your capital plus the returns that have already accumulated, not on the capital alone. The gap looks small in year one, then widens every year because the base you earn on keeps growing.
The compound interest calculator at the top of this page recalculates the moment you type, with no calculate button. It gives you the final value and total profit, a chart of your investment growing year by year, and a detailed annual table you can copy or download as an Excel file.
If you are not sure what numbers to enter, click one of the ready-made examples above the form — Starting to save, Saving for tuition, Lump sum with no deposits, or Early retirement — and every field fills with a realistic scenario, with the result appearing straight away. The Random example button generates different numbers on every click, if you want to see how the outcome moves as the inputs change.
Compound interest vs simple interest
Simple interest is calculated on the original amount only for the whole term, so it adds a fixed amount each year. Compound interest is added back into the capital at the end of each period, and the next period’s interest is calculated on the new total.
The result is accelerating growth rather than linear growth. This is the core of the time value of money: a riyal today is not worth a riyal ten years from now.
How to calculate compound interest: the full formula
For a single amount with nothing added to it, the formula is:
Final value = Principal x (1 + annual rate / compounding frequency) ^ (compounding frequency x years)
- Principal: the amount you start with.
- Annual rate: the expected yearly return, so 7% enters the formula as 0.07.
- Compounding frequency: how many times returns are added back into the capital per year: 12 monthly, 4 quarterly, 2 semi annually, 1 annually.
- Years: how long the money stays invested.
That formula is not enough once you add a monthly deposit, because each deposit arrives at a different time and only earns interest for the time it is actually held. So the calculator works month by month: it adds the deposit at the start of the month, then grows the balance by a monthly growth factor derived from the annual rate and the compounding frequency:
Monthly growth factor = (1 + annual rate / compounding frequency) ^ (compounding frequency / 12)
This way every riyal earns interest for the time it was really invested, not for a full period it never spent.
The clearest way to see what the formula does is to watch the base itself grow. Take 1,000 at 10% a year, with no monthly deposit, compounded annually:
| Year | Base at the start of the year | Interest (10%) | Closing balance |
|---|---|---|---|
| 1 | 1,000.00 | 100.00 | 1,100.00 |
| 2 | 1,100.00 | 110.00 | 1,210.00 |
| 3 | 1,210.00 | 121.00 | 1,331.00 |
The rate is a flat 10% in all three years, yet the interest climbs from 100 to 110 to 121. The base the rate is applied to grows every year by the previous year’s interest. That is compounding, and all the calculator above does is repeat that step month by month for as many years as you enter.
How to use the Qoyod compound interest calculator
- Currency: pick your currency from the list. The calculator supports the Saudi riyal, Jordanian dinar, UAE dirham, Egyptian pound, Kuwaiti dinar, and Bahraini dinar.
- Principal: the capital you start with.
- Monthly deposit: the amount you add each month. Leave it at zero for a one off investment.
- Annual interest rate: the expected return, as a percentage.
- Years: the investment horizon.
- Compounding frequency: monthly, quarterly, semi annually, or annually.
Results appear right after the last field you fill in: total profit, final investment value, total amount invested, and how many times interest is compounded per year. Below them, a chart splits each year’s balance into three sources: the principal, total deposits, and accumulated interest.
The annual table under the chart shows, for each year, the opening balance, the deposits made, the interest earned, and the closing balance. You can copy the whole table with one button or download it as an Excel file to use in a financial model or share with your accountant.
A fully worked example
Take these inputs: a principal of SAR 10,000, a monthly deposit of SAR 1,000, an annual rate of 7%, a term of 10 years, and monthly compounding.
- Total amount invested: SAR 130,000, which is SAR 10,000 of capital plus SAR 120,000 of deposits over 120 months.
- Final value: SAR 194,191.08.
- Total profit: SAR 64,191.08.
Interest alone added roughly half of what you put in, without a single extra riyal of deposits.
Does compounding frequency change the result?
Yes. The more often returns are added back into the capital during the year, the earlier those returns join the growth cycle. Using the same inputs as the example above and changing only the frequency:
| Compounding frequency | Final value | Difference vs annual |
|---|---|---|
| Annually | SAR 191,690.40 | 0 |
| Semi annually | SAR 193,023.69 | SAR 1,333.29 |
| Quarterly | SAR 193,717.71 | SAR 2,027.31 |
| Monthly | SAR 194,191.08 | SAR 2,500.68 |
That gap between the rate you are quoted and the rate you actually collect is the difference between the nominal interest rate and the effective interest rate. When comparing two bank offers, compare the effective rate, not the nominal one.
The three factors that decide how much compounding gives you
Three inputs drive the result, and their weight is nowhere near equal. Here they are strongest first — an order that surprises most people.
Time, by a wide margin. Put 10,000 in at 8% a year and leave it. After 10 years it is 21,589.25. After 20, 46,609.57. After 30, 100,626.57. The last ten years alone added more than 54,000 — more than the first twenty put together. Time does not multiply the result, it raises it exponentially.
Then the rate. Same amount, same twenty years, at 6% instead of 8%: 32,071.35 rather than 46,609.57. Two percentage points, a gap of more than 14,500. But higher rates normally carry higher risk, and the figure you type into the calculator is your assumption, not anybody’s promise.
The amount comes last. Doubling your capital doubles the result and nothing more: 20,000 at 5% for five years gives 25,525.63, exactly twice what 10,000 gives. Its effect is linear, unlike time. Which is why starting small and early beats waiting for a large amount later.
Three worked examples, step by step
These run with no monthly deposits, so you can see the formula on its own. Add a monthly deposit and the calculator above handles it for you.
One — 10,000 at 5% for five years.
Final value = 10,000 × (1 + 0.05)^5 = 10,000 × 1.27628 = 12,762.82.
That is 2,762.82 in profit. Simple interest would have paid 2,500, so compounding alone added 262.82.
Two — same amount, 10%, ten years.
Final value = 10,000 × (1 + 0.10)^10 = 10,000 × 2.59374 = 25,937.42.
More than two and a half times the money without adding a single unit.
Three — quarterly compounding.
5,000 in a fund paying 2% per quarter, for two years. Periods = 2 × 4 = 8 quarters.
Final value = 5,000 × (1 + 0.02)^8 = 5,000 × 1.17166 = 5,858.30.
What matters here is that the rate and the period must agree: a quarterly rate with a count of quarters, never an annual rate with a count of years. Mixing the two is the most common mistake in hand-calculated compound interest.
What compounding does over thirty years
10,000 at 10% a year, with nothing added:
| After | Value | Accumulated interest |
|---|---|---|
| 10 years | 25,937.42 | 15,937.42 |
| 20 years | 67,275.00 | 57,275.00 |
| 30 years | 174,494.02 | 164,494.02 |
The amount invested never changed — 10,000 in all three rows. Only the time did. Between year twenty and year thirty the investment added 107,219, more than twice what it added in the whole twenty years before that. This is why delaying the start costs far more than it looks like it should.
Putting compounding to work
Those numbers reduce to four rules — not general advice, but direct consequences of what you just saw:
- Start now, not when the amount is bigger. Ten years of delay in the last example cost more than 54,000, more than any extra saving over those years would have covered.
- Reinvest the returns instead of withdrawing them. Withdrawing turns compound interest back into simple interest and cancels everything above.
- Deposit regularly. A monthly deposit adds a new base every month, which is why the calculator above works month by month rather than once at year end.
- Compare on the effective rate, not the nominal one. Two offers quoting the same headline rate can pay differently if they compound at different frequencies, as the table above shows.
If what you need is not the growth of an amount over time but investment arithmetic solved for a specific unknown, the investment calculator fits better.
Related calculators and templates
- ROI calculator to measure the return on an investment that has already run, rather than projecting growth.
- Loan payment template for when compounding works against you in a loan instead of for you in an investment.
- Percentage calculator for quick ratio math.
- Profit margin calculator to check how much of your revenue survives as profit.
Frequently asked questions
What is the difference between simple and compound interest?
Simple interest is calculated on the original amount only, so it adds a fixed sum each year. Compound interest is calculated on the original amount plus prior earnings, so it grows faster the longer the term runs.
Does compounding frequency change the result?
Yes. With a principal of 10,000, a monthly deposit of 1,000, and a 7% rate over 10 years, the final value is 191,690.40 with annual compounding and 194,191.08 with monthly compounding, a gap of about 2,500 from the frequency alone.
How does the calculator handle monthly deposits?
It adds the deposit at the start of each month, then grows the balance by a monthly growth factor derived from the annual rate and the compounding frequency. That way each deposit earns interest only for the time it was actually held.
Does the calculator account for taxes or fees?
No. Results are based on the numbers you enter, before any taxes or administrative fees. For a result closer to reality, enter the net interest rate after the taxes and fees you expect.
Can I save or download the results?
Yes. The detailed annual table has a button to copy the full table and a button to download it as an Excel file, so you can carry on working with it in your own model.
Does the calculator work in currencies other than the Saudi riyal?
Yes. Pick the currency at the top of the form. The calculator supports the Saudi riyal, Jordanian dinar, UAE dirham, Egyptian pound, Kuwaiti dinar, and Bahraini dinar.
This calculator is a math tool that projects how an amount grows at a return rate you assume. It is not investment advice and not a promise of any return. Your actual rate depends on the instrument you choose.
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