Project growth with regular deposits, compare two scenarios, and separate contributions from interest.
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| Year | Contributions | Interest | Balance |
|---|---|---|---|
| 0.0 | 10,000.00 | 0.00 | 10,000.00 |
| 1.0 | 10,000.00 | 722.90 | 10,722.90 |
| 2.0 | 10,000.00 | 1,498.06 | 11,498.06 |
| 3.0 | 10,000.00 | 2,329.26 | 12,329.26 |
| 4.0 | 10,000.00 | 3,220.54 | 13,220.54 |
| 5.0 | 10,000.00 | 4,176.25 | 14,176.25 |
| 6.0 | 10,000.00 | 5,201.06 | 15,201.06 |
| 7.0 | 10,000.00 | 6,299.94 | 16,299.94 |
| 8.0 | 10,000.00 | 7,478.26 | 17,478.26 |
| 9.0 | 10,000.00 | 8,741.77 | 18,741.77 |
| 10.0 | 10,000.00 | 10,096.61 | 20,096.61 |
Compound interest is growth calculated on the initial principal and previously accumulated interest. Growth uses a constant nominal annual rate and fractional compounding periods between deposit dates. Monthly or annual deposits use the selected start/end timing; only complete deposit periods count. Taxes, fees and inflation are excluded; returns are not guaranteed. B−A compares the selected final balances, which may have different time horizons. The annual table and growth chart show A.
Recomputed from this page's implementation at build time · checked 2026-10-22
Compounding frequency is the quietest input on the page and the second-largest lever after time. On a 30-year horizon it moves the result by more than five thousand, then the curve flattens so hard that going from twelve periods a year to three hundred and sixty-five adds under five hundred.
| 3 | 4 | 5 | 6 | 7 | 8 | |
|---|---|---|---|---|---|---|
| 10 | $13,494 | $14,908 | $16,470 | $18,194 | $20,097 | $22,196 |
| 20 | $18,208 | $22,226 | $27,126 | $33,102 | $40,387 | $49,268 |
| 30 | $24,568 | $33,135 | $44,677 | $60,226 | $81,165 | $109,357 |
| 40 | $33,151 | $49,399 | $73,584 | $109,575 | $163,114 | $242,734 |
Read the columns, not the rows. Going from 3 to 8 per cent is a smaller change than going from 10 to 40 years at any single rate, which is the ordering most people get backwards when they shop for a rate instead of waiting.
Everything in the third row is growth, and it is more than four times what was paid in. Set against the yearly figure above, monthly compounding alone adds 5,042.42 — more than the interest earned across the first five years combined. That is the size of the lever, and nobody had to change the rate.
The deposit is added after interest is credited for that period, so each one starts earning in the following month. Paid-in money is 10,000 plus 360 deposits of 100, and the rest is growth. This ordering is the common bank convention and the one the page assumes unless you change it.
Same 46,000 paid in, and the balance is higher because every deposit collects one extra month of interest — 360 of them, compounding on each other for three decades. The paid-in row does not move at all. That is what makes the timing control worth exposing: it changes only the growth, never the contribution.
The contribution row is identical to the monthly case, down to the cent, because 100 a month and 1,200 a year are the same 46,000. The balance is not: a year of deposits sitting in cash at the end of each year misses the growth the monthly schedule had already collected. Annual saving is a habit decision, and it shows up here as a cost.
The comparison exists to make one point visible: the last twenty years add four times what the first ten did, on the same monthly deposit. Read the difference as the price of starting late rather than as a gain, since both scenarios pay in the same amount every month from the same starting balance.
inputError
A compounding frequency of twice a year
The frequency control is a four-item whitelist — yearly, quarterly, monthly, daily — not a free number. Semi-annual and bi-weekly are missing rather than approximated into the nearest neighbour, because silently rounding 2 up to 4 would misstate the balance without any visible warning.
inputError
A negative starting balance
This page projects a savings balance, so both the principal and the deposit must be non-negative. A debt payoff calculation inverts the sign of every term and belongs to a different tool rather than to a special case here.
inputError
A hundred and one years
The cap is a hundred years. Beyond that the balance table grows to the point of being unreadable and the result stops being a number anyone plans with — at 7% monthly, a century already multiplies the principal more than a thousandfold.
inputError
A rate of one hundred and one percent
The rate runs from minus one hundred to plus one hundred, inclusive at both ends. The negative end is real and usable; the upper cap exists so that a typo in the slider cannot produce a balance in the trillions that still renders like a plausible answer.
Calculator.net compound interestchecked 2026-10-22
Why they built it that wayThe form is built around a single deposit, with recurring contributions added afterwards. That is why deposit timing is a small dropdown instead of a first-class field: the page originally answered a different question.
Converting a rate and projecting a balance are different questions. This page cannot tell you the annual equivalent of a rate compounded daily; it answers what the balance becomes, deposits included, which is usually the reason someone opened a compound interest calculator in the first place.
Enter 10,000 at 7% for 30 years with no deposits and step through the four frequencies: 76,122.55 yearly, 80,191.83 quarterly, 81,164.97 monthly, 81,645.26 daily. Then add 100 a month and switch the timing control from end to begin — the paid-in total stays at 46,000 while the balance rises.
Checked against the closed form, plus a zero-rate case that must land exactly on the deposit total · impl 47631576
Apply the nominal annual rate divided by the compounding frequency to the initial balance. Each recurring deposit grows from its scheduled beginning or end of a complete month or year; a partial final deposit period adds growth but no new deposit. At 0% interest, an initial 1000 plus twelve monthly deposits of 100 ends at 2200 after one year. Total deposited includes the initial amount; interest is final balance minus that total. Scenario B uses its own rate, deposit and duration, while the annual table and chart show A. A B − A difference with different durations is a balance comparison, not an equal-time return comparison. Supported limits are 1 billion initially, 10 million per deposit, 0–100 years and −100% to 100% nominal annual interest. Taxes, fees and inflation are excluded; returns are not guaranteed.
These calculators give estimates for general information only. They are not financial, tax or investment advice and do not take your personal circumstances into account. Before borrowing, investing or filing, confirm the numbers with a qualified adviser in your jurisdiction.
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
A = P·b^(n·t) + Σⱼ₌₁ᴺ C·b^(n·(t−(j−δ)/f)); b = 1+r/n; N = ⌊f·t⌋; I = A−(P+C·N)
Growth uses a constant nominal annual rate and fractional compounding periods between deposit dates. Monthly or annual deposits use the selected start/end timing; only complete deposit periods count. Taxes, fees and inflation are excluded; returns are not guaranteed. B−A compares the selected final balances, which may have different time horizons. The annual table and growth chart show A.
Compound interest is growth calculated on the initial principal and previously accumulated interest. With no recurring deposits, the model uses P × (1 + r/n)^(n × t), where r is the nominal annual rate as a decimal, n is the number of compounding periods per year and t is years.
Choose monthly or annual deposits and period beginning or end. Only complete deposit periods count. For example, 1.5 months includes one monthly deposit; the remaining half-month adds growth but no second deposit. At 0% interest, an initial 1000 plus twelve monthly deposits of 100 ends at 2200 after one year.
Total deposited is the initial amount plus scheduled deposits. Interest is the final balance minus that total and can be negative. These are fixed-rate projections excluding taxes, fees and inflation; returns are not guaranteed.
B − A subtracts the selected final balance of A from B. Each scenario uses its own rate, deposit and duration. If durations differ, this is not an equal-time return comparison. The annual table and growth chart show scenario A.