Free Lumpsum Investment Calculator — One-Time Growth
November 2, 2026 · 3 min read · By the DollarWise team
How it works
A lumpsum investment puts all your money to work on day one. Enter the one-time amount, the annual return you expect and the number of years it will stay invested — this calculator compounds it annually, shows the future value and your gains, and compares it against investing the same total gradually through a monthly SIP.
## How the math works
A lumpsum earns compound interest from the very first day. With principal P, annual return r and years t, the future value is:
**FV = P × (1 + r)^t**
Gains are simply FV − P. The comparison against a SIP invests the same total P spread evenly across n = t × 12 monthly payments at the same annual return, using the standard SIP formula FV = monthly × [((1 + i)^n − 1) ÷ i] × (1 + i) with i = r ÷ 1200. Because the lumpsum is fully invested from day one while SIP money trickles in, the lumpsum almost always ends ahead at the same return.
## Everyday uses
- **Bonus or inheritance planning:** see what a one-time windfall could become if invested rather than spent.
- **Lumpsum vs SIP decision:** compare putting money in now against spreading it over months to decide which fits your risk tolerance.
- **Retirement gap check:** calculate how much extra a one-time top-up adds to your final retirement balance.
## Frequently asked questions
### Is a lumpsum always better than a SIP?
At the same rate of return, yes mathematically, because the full sum is invested longer. But markets can fall right after you invest, so a SIP reduces the risk of buying at a peak. The choice depends on your risk tolerance and market view, not just the math.
### What return should I assume?
Long-run diversified stock portfolios have averaged roughly 7–10% a year, bonds much less. Use a range — try 7% as a conservative case and 10–12% as optimistic — rather than planning around a single best-case number.
### Does this account for taxes and fees?
No. The projection is gross of fund fees, taxes and inflation, and assumes smooth returns. Your actual spendable amount will be lower. For PKR amounts, just treat every $ as Rs. — the compounding formula is currency-neutral.