Fill in your amounts on the left and click Calculate to see how your extra funds grow.
An additional fund is any money you put into a savings or investment account on top of what is already there. It could be a single large deposit — like a tax refund, work bonus, or inheritance — or a fixed extra amount you add every month alongside your normal contributions.
Even a small additional fund makes a bigger difference than most people expect, because of compound interest. Every extra dollar you add starts earning returns, and those returns earn more returns over time. The sooner you add the money, the longer it has to grow.
This calculator shows you the complete picture: how much your extra money is worth at the end of your chosen period, how much interest it alone generates, and how much better off you are compared to doing nothing extra. If you are working toward a specific target, try the savings goal calculator to find out exactly how long it takes to get there.
The calculator uses the standard compound interest formula with monthly additions:
Example: $5,000 balance + $2,000 lump sum + $200/month at 5% for 10 years → Future balance of approximately $42,800, with over $11,800 in interest earned. Not sure how much you can set aside each month? The daily budget calculator can help you find money to put toward your extra contributions.
| Lump Sum | 5 Years @ 5% | 10 Years @ 5% | 20 Years @ 7% |
|---|---|---|---|
| $500 | $638 | $815 | $1,935 |
| $1,000 | $1,276 | $1,629 | $3,870 |
| $2,500 | $3,190 | $4,072 | $9,675 |
| $5,000 | $6,381 | $8,144 | $19,349 |
| $10,000 | $12,763 | $16,289 | $38,697 |
| $25,000 | $31,907 | $40,722 | $96,742 |
| $50,000 | $63,814 | $81,445 | $193,484 |
Values use monthly compounding. Past rates do not guarantee future results. To see how growing funds fit into your overall financial picture, the net worth calculator tracks all your assets and liabilities in one place.
| Extra / Month | 5 Years @ 5% | 10 Years @ 5% | 20 Years @ 7% |
|---|---|---|---|
| $50/mo | $3,400 | $7,764 | $26,208 |
| $100/mo | $6,801 | $15,528 | $52,397 |
| $200/mo | $13,601 | $31,056 | $104,794 |
| $500/mo | $34,003 | $77,641 | $261,985 |
| $1,000/mo | $68,006 | $155,283 | $523,971 |
Assumes contributions at start of each month with monthly compounding.
How a one-time extra deposit grows at different annual interest rates over 10 years.
| Lump Sum | 2% | 3% | 4% | 5% | 6% | 7% | 8% | 10% | Interest Gain @5% |
|---|
Year-by-year growth of a combined lump-sum and monthly addition strategy.
| Year | Starting Balance | Interest Earned | Contributions | Ending Balance |
|---|
Future value of different monthly additions at various rates over 10 years.
| Extra / Month | 3% | 4% | 5% | 6% | 7% | 8% | Total Added |
|---|
Use these as a starting point for your interest rate input.
| Account Type | Typical Rate | Risk | Notes |
|---|---|---|---|
| Basic Savings Account | 0.5 – 1% | Very Low | FDIC/FSCS insured, easy access |
| High-Yield Savings | 4 – 5.5% | Very Low | Online banks, currently competitive |
| Money Market Account | 4 – 5% | Very Low | May require minimum balance |
| Certificate of Deposit | 4 – 5.5% | Very Low | Locked for fixed term |
| Bonds / Bond Funds | 3 – 5% | Low–Medium | Government or corporate |
| Balanced Portfolio | 5 – 7% | Medium | 60/40 stocks/bonds, historical avg |
| Stock Index Fund | 7 – 10% | Higher | Long-term historical, not guaranteed |
| Real Estate (REITs) | 6 – 9% | Medium–High | Dividends + price growth |
Real (purchasing power) value of a lump sum after inflation erodes it — why growing your money matters.
| Years | Nominal | Real @ 2% Inflation | Real @ 3% | Real @ 4% | Real @ 5% |
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