— Investment
Monthly Investment Required Calculator
Set a target and find the monthly investment that gets you there — the reverse of projecting a fixed contribution forward.
Required monthly investment
$1,981.86
- Total you will invest
- $356,735.16
- Total gains
- $643,264.84
- Target amount
- $1,000,000
— Year by year
| Year | Invested | Gains | Balance |
|---|---|---|---|
| 1 | $23,782.34 | $1,603.98 | $25,386.32 |
| 2 | $47,564.69 | $6,427.57 | $53,992.26 |
| 3 | $71,347.03 | $14,879.12 | $86,226.15 |
| 4 | $95,129.38 | $27,418.73 | $122,548.11 |
| 5 | $118,911.72 | $44,564.88 | $163,476.6 |
| 6 | $142,694.06 | $66,901.78 | $209,595.84 |
| 7 | $166,476.41 | $95,087.75 | $261,564.16 |
| 8 | $190,258.75 | $129,864.61 | $320,123.36 |
| 9 | $214,041.1 | $172,068.24 | $386,109.34 |
| 10 | $237,823.44 | $222,640.55 | $460,463.99 |
| 11 | $261,605.78 | $282,642.88 | $544,248.67 |
| 12 | $285,388.13 | $353,271.21 | $638,659.34 |
| 13 | $309,170.47 | $435,873.18 | $745,043.65 |
| 14 | $332,952.82 | $531,967.34 | $864,920.15 |
| 15 | $356,735.16 | $643,264.84 | $1,000,000 |
— Path to your target
Download— How it works
P = (target − initial·(1 + i)ⁿ) × i ÷ [((1 + i)ⁿ − 1)(1 + i)]; i = monthly rate, n = months (start-of-period)
Working backwards from a goal
Most projection tools ask “if I invest this much, what will I have?”. This one flips the question: you name the amount you want and the time you have, and it solves for the monthly investment that gets you there. It is the algebraic inverse of a SIP projection — the same annuity relationship, rearranged to find the contribution.
The headline is the level monthly amount needed; the chart then traces that plan climbing year by year until it meets the target line at the end. Because the contribution is solved to land exactly on the goal, the path always finishes on the line — the value is in seeing how steep the climb is and how much of the final corpus is your own money versus growth.
Worked example — reach $1,000,000 in 15 years at 12%: You would need to invest roughly $1,980 a month. Over 15 years that is about $356,000 of your own money; the remaining $644,000 is growth.
Current savings, step-up and goal inflation
Three advanced levers change the picture. Money you have already saved compounds toward the goal alongside your contributions, so it lowers the monthly amount needed — the calculator shows that reduced figure when you enter a current balance. A planned annual step-up lets you start lower and raise the contribution each year, which suits a rising income; the “starting monthly” figure shows where you would begin.
Goal inflation matters most for distant goals. A target that sounds ample today — a child’s education, a retirement pot — will cost more in future money. Switch on a goal-inflation rate and the calculator grows the target to its future value, then shows the monthly needed to hit that larger, purchasing-power-preserving figure.
How this differs from the related tools
This calculator fixes the goal and solves for the contribution. The SIP and Monthly Contribution calculators do the opposite — fix the contribution and project the result. The Investment Goal calculator runs a complete plan forward to check whether it reaches a target, and the broader Investment Calculator lets you solve for any single lever — contribution, return, starting amount or time. Reach for this one when the contribution is the specific unknown you want, with goal inflation and step-up built in.
— Reader questions
How is this different from a SIP calculator?
A SIP calculator is forward-looking: you enter a monthly amount and it shows the maturity value. This one runs the same maths in reverse — you enter the maturity value (your target) and it solves for the monthly amount needed. They are two sides of the same annuity formula.
Does my current savings reduce the monthly amount?
Yes. Anything you have already saved keeps compounding toward the goal, so it does part of the work. Enter it under Advanced options and the calculator shows the lower monthly contribution you then need.
What does the goal inflation adjustment do?
It grows your target by the rate you set, so the goal keeps its real purchasing power. A million today will not buy the same in 15 years; with goal inflation on, the calculator targets the larger future figure and tells you the monthly amount required to reach it.
Why does a step-up let me start with less?
If you commit to raising your contribution each year, your later, larger contributions still have time to grow. That lets the early years be lighter, so the starting monthly amount is lower than a flat contribution would be.
What return should I assume?
Use a rate that matches where you will invest. Long-run equity returns have historically been higher but volatile; cash and bonds lower and steadier. A higher assumed return lowers the monthly amount needed — so it pays to be realistic rather than optimistic.
Is the result guaranteed?
No. It assumes a steady return every year, which real markets do not deliver. Treat the monthly figure as a sensible target rather than a promise, and revisit it as your returns and circumstances change.