Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Projecting an existing balance plus ongoing contributions is highly sensitive to the assumed rate of return over a multi-decade horizon, since small differences in that single assumption compound into large differences in the projected ending balance the longer the projection runs.
Before you rely on it
What to check
Check whether the current saving path is actually approaching your goal at more than one plausible return assumption, not just a single optimistic one.
The common error
Where people go wrong with retirement savings calculator
Anchoring a retirement plan on a single, possibly optimistic, assumed rate of return projected decades into the future. A more conservative assumption run alongside it reveals how sensitive the whole plan actually is to that one number.
Sensitivity evidence
How expected annual return changes the future value
| Expected annual return | Future value | Estimated growth |
|---|---|---|
| 5.0% | $755,162 | $447,162 |
| 6.0% | $924,064 | $616,064 |
| 7.0%worked example | $1,138,307 | $830,307 |
| 8.0% | $1,411,002 | $1,103,002 |
| 9.0% | $1,759,206 | $1,451,206 |
Every input, tested
Which input moves the future value most
| Input | Tested from | To | Future value at each end | Swing |
|---|---|---|---|---|
| Time horizon | 22.0 years | 38.0 years | $592,592 to $2,092,122 | $1,499,530 (132%) |
| Expected annual return | 6.0% | 8.0% | $924,064 to $1,411,002 | $486,939 (43%) |
| Monthly contribution | $720 | $880 | $1,040,709 to $1,235,904 | $195,195 (17%) |
| Starting amount | $18,000 | $22,000 | $1,122,074 to $1,154,540 | $32,466 (2.9%) |
| Compounds per year | Annually | Daily | $1,128,222 to $1,139,267 | $11,045 (1.0%) |
Two variables at once
Future value by expected annual return and starting amount
| Expected annual return \ Starting amount | $16,000 | $20,000 | $24,000 |
|---|---|---|---|
| 5.0% | $737,291 | $755,162 | $773,033 |
| 6.0% | $899,973 | $924,064 | $948,154 |
| 7.0% | $1,105,841 | $1,138,307 | $1,170,773 |
| 8.0% | $1,367,259 | $1,411,002 | $1,454,745 |
| 9.0% | $1,700,284 | $1,759,206 | $1,818,129 |
Step by step
The worked example, input by input
| Input | Value used |
|---|---|
| Starting amount | $20,000 |
| Monthly contribution | $800 |
| Expected annual return | 7.0% |
| Time horizon | 30.0 years |
| Compounds per year | Monthly |
| Future value | $1,138,307 |
| Estimated growth | $830,307 |
Complete evidence
Full projection schedule
Show all 30 rows
| Period | Opening balance | Contribution | Growth | Ending balance |
|---|---|---|---|---|
| Year 1 | $20,000 | $9,600 | $1,400 | $31,000 |
| Year 2 | $31,000 | $9,600 | $2,170 | $42,770 |
| Year 3 | $42,770 | $9,600 | $2,994 | $55,364 |
| Year 4 | $55,364 | $9,600 | $3,875 | $68,839 |
| Year 5 | $68,839 | $9,600 | $4,819 | $83,258 |
| Year 6 | $83,258 | $9,600 | $5,828 | $98,686 |
| Year 7 | $98,686 | $9,600 | $6,908 | $115,194 |
| Year 8 | $115,194 | $9,600 | $8,064 | $132,858 |
| Year 9 | $132,858 | $9,600 | $9,300 | $151,758 |
| Year 10 | $151,758 | $9,600 | $10,623 | $171,981 |
| Year 11 | $171,981 | $9,600 | $12,039 | $193,620 |
| Year 12 | $193,620 | $9,600 | $13,553 | $216,773 |
| Year 13 | $216,773 | $9,600 | $15,174 | $241,547 |
| Year 14 | $241,547 | $9,600 | $16,908 | $268,055 |
| Year 15 | $268,055 | $9,600 | $18,764 | $296,419 |
| Year 16 | $296,419 | $9,600 | $20,749 | $326,769 |
| Year 17 | $326,769 | $9,600 | $22,874 | $359,242 |
| Year 18 | $359,242 | $9,600 | $25,147 | $393,989 |
| Year 19 | $393,989 | $9,600 | $27,579 | $431,169 |
| Year 20 | $431,169 | $9,600 | $30,182 | $470,950 |
| Year 21 | $470,950 | $9,600 | $32,967 | $513,517 |
| Year 22 | $513,517 | $9,600 | $35,946 | $559,063 |
| Year 23 | $559,063 | $9,600 | $39,134 | $607,798 |
| Year 24 | $607,798 | $9,600 | $42,546 | $659,943 |
| Year 25 | $659,943 | $9,600 | $46,196 | $715,739 |
| Year 26 | $715,739 | $9,600 | $50,102 | $775,441 |
| Year 27 | $775,441 | $9,600 | $54,281 | $839,322 |
| Year 28 | $839,322 | $9,600 | $58,753 | $907,675 |
| Year 29 | $907,675 | $9,600 | $63,537 | $980,812 |
| Year 30 | $980,812 | $9,600 | $68,657 | $1,059,069 |
Where the inputs come from
Starting amount is the total of every retirement account today: 401(k), IRAs and any old workplace plans, valued from the latest statements. Monthly contribution is what goes in each month, including your employer's match, which is free money and belongs in the total. Expected return is a planning assumption after fees, and the horizon is the years until you plan to stop working. Many people forget old accounts from previous employers, which can hold thousands.
When the result stops applying
The projection is in future dollars, so a million in 30 years buys much less than a million today. It assumes a constant return and steady contributions, while real careers include raises, gaps and market crashes near retirement. It ignores taxes on withdrawals from traditional accounts, which reduce what you can spend. Run a second case at a lower return and one at your inflation-adjusted contribution.
What to compare it with
Set the projected balance against a target using the retirement goal calculator, and translate it into income with the retirement withdrawal calculator. Check whether you capture the full employer match with the 401(k) match calculator, and the IRA growth page for a separate account. Raising your contribution by 1% of pay each year is one of the easiest changes that moves the outcome.
Worked examples for the Retirement Savings Calculator
3 real questions people ask, each worked through with this calculator at its own numbers.
How much will $10,000 plus $500 a month grow to at 7% over 30 years?
| Starting amount | $10,000 |
|---|---|
| Monthly contribution | $500 |
| Expected annual return | 7.0% |
| Time horizon | 30.0 years |
| Compounds per year | 12 |
| Future value | $691,150 |
The same contributions as the twenty-year version, given another decade. Compounding is not linear. So the extra ten years adds far more than half of what the first twenty produced. That back-loading is why leaving a portfolio alone in the final stretch matters so much and why withdrawing early costs more than it appears to.
Look at the difference between the twenty and thirty year results. Those last ten years are worth more than the first twenty.
Thirty years brings a rule most projections ignore: inflation. A large nominal figure at the end represents much less purchasing power than it looks. The other issue is that the assumed rate covers a period that will include several bad years, and the order they arrive in changes the result even if the average is the same.
Divide the final figure by the cumulative inflation you expect over thirty years to see it in today's money. At an assumed inflation of about three percent a year, the result is roughly cut by more than half.
How much will $50,000 plus $1,000 a month grow to at 6% over 20 years?
| Starting amount | $50,000 |
|---|---|
| Monthly contribution | $1,000 |
| Expected annual return | 6.0% |
| Time horizon | 20.0 years |
| Compounds per year | 12 |
| Future value | $627,551 |
A substantial starting balance and a substantial monthly commitment, at a conservative rate. This is what a serious mid-career savings plan looks like on paper. Six percent is a deliberately unexciting assumption, which makes the result more trustworthy than the same plan modelled at nine.
A conservative rate that still reaches the goal is a better plan than an aggressive one that only just does.
This plan is strong, and the weak point is the assumption that the contributions never stop. A job change, a health event or a child's education cost can interrupt a thousand a month more easily than any market can. It is worth knowing how much of the result depends on the last five years of contributions, since those are the ones that get skipped when times are hard.
Remove the final five years of contributions and re-run. The difference shows how much of the plan you would still have if the schedule ended early.
How much will $0 plus $500 a month grow to at 7% over 40 years?
| Starting amount | $0.00 |
|---|---|
| Monthly contribution | $500 |
| Expected annual return | 7.0% |
| Time horizon | 40.0 years |
| Compounds per year | 12 |
| Future value | $1,312,407 |
Five hundred a month, from zero, for forty years. No lump sum, no windfall, nothing but consistency. What this really models is a career of steady retirement contributions, and it is worth comparing against the same amount over twenty years to see exactly what the extra time is worth.
The contributions are the easy part to picture and the smaller part of the outcome. Time does most of the work here.
Retirement accounts often have an employer match, and the assumption here leaves it out. Where a match exists, it is an immediate return on the contribution that no market assumption can compete with. Missing it is the most expensive way to save less. Contribution limits also apply to tax-advantaged accounts, and a monthly amount that fits under them today may not after a large raise.
Check whether an employer match applies to you and add it to the monthly figure in the calculator. Then confirm the total sits under the annual limit for the account type.
People also ask
Frequently asked questions
How much should I have saved by retirement?
A common guide is 25 times your first-year spending, based on the 4% rule, so spending $60,000 a year points to about $1.5 million. Social Security and pensions reduce the amount you must save.
What return should I assume for a long horizon?
Many planners use 5% to 7% after fees for a stock-heavy portfolio and lower for conservative mixes. Testing a lower rate shows how much your plan depends on strong markets.
Does this include Social Security?
No. The result is only what your own savings could grow to. Estimate Social Security separately and subtract it from spending when you size the target.