Investment Calculator (Monthly Contributions, Any Currency)
What a regular investment grows to — or what it takes to reach your goal.
Returns are not guaranteed: investments can fall in value, and this projection assumes the same return every year, with no tax or fees.
Growth year by year
Year-by-year breakdown
How this was calculated
Results are estimates for general information and planning, not financial advice. Banks and institutions may calculate differently (rounding, fees, rate changes). Confirm figures with your lender or a qualified adviser before deciding.
About the Investment Calculator (Monthly Contributions, Any Currency)
Enter what you start with, what you add every week, two weeks, month, quarter or year, and the return you expect, and see what the investment could grow to — with the part you put in and the part that is growth, year by year. The same plan answers three more questions: the contribution needed to reach a target, the return needed, and the time to reach it.
Contributions can be made at the start or the end of each period and can rise every year by a percentage or a fixed amount. The return can be compounded yearly (an effective rate, the way fund returns are reported), half-yearly, quarterly, monthly, daily or continuously. Add an inflation rate to see the result in today’s money. It works in any currency: amounts follow your country’s number format and the currency’s own decimal places, and no tax is assumed.
How to use it
- Choose what to work out: Balance, Contribution needed, Return needed or Time to goal, and the currency.
- Enter the starting amount and the regular contribution, how often you add it and whether at the start or the end of each period. Add a yearly increase if your contributions rise with your pay.
- Enter the expected return per year and how it is compounded, and the number of years — or the target for the three goal questions.
- Optionally enter inflation: values are then also shown in today’s money, and a target is treated as today’s money.
- Read the answer, the chart and the year-by-year table; copy the summary or download the table as CSV.
Examples
Balance 292,465.03 · put in 130,000 · growth 162,465.03
Contributions earn the monthly equivalent of 7% a year: 1.07^(1/12) − 1 = 0.5654% a month.
Balance 81,939.67 (0.5% a month: the textbook annuity factor 163.879)
855.10 a month — or 131,367.12 invested once today
7.18% a year (2^(1/10) − 1)
10 years 3 months (10.24 years: ln 2 ÷ ln 1.07)
Common uses
- Seeing what a monthly investment in an index fund or a retirement account could grow to.
- Working out how much to invest every month, or every payday, to reach a goal by a date.
- Checking what return a plan quietly assumes before you rely on it.
- Comparing contributions at the start or the end of the month, or with a yearly increase.
How the balance is calculated
The return r you enter is a yearly rate compounded m times a year, so it grows money by the effective annual rate EAR = (1 + r ÷ m)^m − 1 (or e^r − 1 compounded continuously). With yearly compounding r is already the effective rate.
Each contribution earns the equivalent rate for its own period, j = (1 + EAR)^(1/k) − 1 for k contributions a year, so every amount grows at the same effective yearly rate however often you contribute. For a level contribution C at the end of each period, over n periods and t years:
FV = S × (1 + EAR)^t + C × [((1 + j)^n − 1) ÷ j]
where S is the starting amount; contributions at the start of each period earn one more period, × (1 + j). With a yearly increase the calculator adds up every contribution grown from the day it is made. How this was calculated under the result shows the formula with your numbers.
Contribution, return and time to a goal
- Contribution needed solves the formula for C exactly (the balance rises in a straight line with the contribution) and also gives the one amount you could invest today instead.
- Return needed finds the yearly return that ends exactly on the target by repeated halving (bisection). It can be negative when the target is less than what you put in.
- Time to goal follows the balance period by period and finds the moment it reaches the target, also between two contributions; the time is shown rounded up to the month in which the target is reached. With inflation the target grows with prices, so the goal is reached later.
Why calculators disagree
Most differences come from two choices: whether the yearly return is turned into a monthly one as r ÷ 12 (which is the same as choosing monthly compounding here, and earns more than r a year) or as the effective (1 + r)^(1/12) − 1 (yearly compounding here), and whether contributions are counted at the start or the end of each period. The U.S. Securities and Exchange Commission’s compound interest calculator on Investor.gov asks for the same core inputs — an initial investment, a monthly contribution, the years, an estimated rate and how often it compounds — so when you compare, set the same compounding and timing. Results can still differ a little, because calculators handle contributions made between two compounding dates in different ways.
Currencies and rounding
The currency starts as your country’s and can be changed to any of about 150 currencies. Amounts are rounded to the currency’s minor units from ISO 4217 List One: two decimals for the dollar or the euro, none for the yen or the won, three for the Kuwaiti dinar. The maths does not depend on the currency, and no tax or fee is taken off.
In India?
The SIP Calculator (India) does the same maths for monthly SIPs in rupees — with yearly compounding and contributions at the start of each month, the two give the same balance — with lakh and crore amounts and India’s step-up and goal modes.
Limitations
- Assumes the same return every year. Real returns go up and down, and the order of good and bad years changes the result of a plan with regular contributions.
- Taxes, fund fees, platform charges and currency conversion are not deducted: use a return that is already after costs.
- Weekly contributions use 52 weeks a year and daily compounding 365 days a year.
- The yearly increase is applied every 12 months from the first contribution.
- Past returns do not guarantee future returns; the result is an estimate, not advice.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
What return should I assume?
There is no safe single number. Use a cautious rate based on the long-run history of what you invest in, after fees, and try two or three rates to see a range. Cash and bonds usually return less than shares over long periods, and shares swing far more from year to year.
Should contributions be at the start or the end of the month?
Choose the start if the money is invested at the beginning of each period (for example the day after payday) and the end if it goes in at the end. At the start, every contribution earns one more period of growth.
What is the difference between yearly and monthly compounding here?
With yearly compounding the rate you enter is the effective yearly return: 7% grows money by exactly 7% a year. With monthly compounding 7% means 7% ÷ 12 a month, which adds up to 7.23% a year. Fund and index returns over several years are usually stated as effective yearly rates (CAGR), so yearly compounding fits them.
How is the value in today’s money worked out?
The balance is divided by (1 + inflation)^years. At 2.5% inflation, 292,465 in 20 years buys about what 178,483 buys today.
Is my money or data sent anywhere?
No. Everything is calculated in your browser, and nothing you type leaves your device.