Retirement Savings Calculator
The useful retirement question is not how large the pot is but what income it produces and for how long. A balance is only meaningful once it is converted into an annual withdrawal that has to last an unknown number of years.
The calculator projects the pot from what you have and what you save, applies a withdrawal rate you choose, and compares the resulting income against the target you enter — then reports the additional monthly saving that would close the gap.
Project the pot and the income
Enter the income you want in today's money, and use a return net of inflation, so the answer is in today's money too.
Withdrawal rate is an assumption, not a rule
The familiar four percent figure came from historical research into how much could be withdrawn from a balanced portfolio, rising with inflation, without exhausting it over a thirty-year retirement. It was a finding about the past, not a guarantee about the future.
It is sensitive to things the headline hides: the length of retirement, the asset mix, fees, and the order in which returns arrive. A poor first decade is far more damaging than the same decade later, because withdrawals are being taken from a shrinking base.
Treat the rate as a dial rather than a constant. Running the projection at a lower rate shows what a more cautious assumption costs in required savings, which is a more useful output than a single confident number.
Work in today's money
Inflation is the reason a projected balance can look ample and buy considerably less than it appears to. Over a long horizon the erosion is substantial.
The cleanest way to handle it is to work entirely in today's money: state the income you want at today's prices, and use a real return — the expected return minus expected inflation — rather than a nominal one. Every figure then means what it appears to mean.
Mixing the two is the common error. A target stated in today's dollars compared against a pot projected at a nominal return overstates readiness by a wide margin, and the mistake is invisible unless you look for it.
If you enter a nominal return, the projected pot is in future dollars and cannot be compared against an income target expressed in today's.
What else funds retirement
The pot in this calculator is one component. Subtract the other reliable sources from your income target before deciding what the invested portion has to produce, or you will conclude you need substantially more than you do.
- Social Security, which for many households covers a meaningful share of the target — get your estimate from the Social Security Administration rather than guessing.
- A defined benefit pension, where one exists.
- Home equity, either through downsizing or by having no housing payment.
- Part-time work in the early years, which reduces the withdrawal rate when it matters most.
- Taxable accounts and cash, which offer flexibility that tax-advantaged accounts do not.
Why starting early dominates everything
The contribution required to reach a given target rises steeply with delay, because each year removed is a year of compounding removed from the front of the sequence where it matters most.
The practical consequence is that a modest contribution begun in your twenties frequently reaches the same place as a much larger one begun in your forties. The total put in is smaller and the result is similar, which is the clearest argument available for starting before the amount feels serious.
It also means a delayed start is not a lost cause, only a more expensive one. The calculator makes the price explicit — run it at your current age and again five years out, and the difference is what waiting costs.
The sequence risk nobody plans for
Two retirements with identical average returns can end very differently depending on when the poor years fall. Losses early, combined with withdrawals, permanently reduce the base that later growth applies to.
The standard responses are holding one to three years of spending in cash or short-duration assets so withdrawals need not come from a fallen market, and being willing to reduce spending temporarily in a bad year.
Neither is visible in a projection built on a smooth average, which is why a projection is a planning tool rather than a forecast. Its value is in comparing scenarios, not in the precision of any single answer.
Reviewing it
Rerun this annually with actual balances rather than projected ones. Reality diverges from any projection quickly, and the point of the exercise is to notice the divergence while there is still time to respond.
The things that most often change the answer are a salary increase not matched by a contribution increase, a period of not contributing, and a fee structure nobody checked. All three are correctable and none announces itself.
Raise contributions with each pay rise before the money is absorbed. Directing half of every raise to retirement is close to painless and is the single most reliable way a projection improves over a career.
Frequently asked questions
Enough that the withdrawal rate you are comfortable with produces your target income, after subtracting Social Security, any pension and other reliable sources. Working backwards from income is more useful than aiming at a round balance.
It was a historical finding rather than a guarantee, and it is sensitive to retirement length, asset mix, fees and the order returns arrive in. Treat it as a dial — running a lower rate shows what caution costs in required savings.
Yes, and the cleanest way is to work entirely in today's money: state the income you want at today's prices and use a return net of inflation. Mixing a today's-money target with a nominal projection overstates readiness substantially.
The risk that poor returns arrive early in retirement, when withdrawals are being taken from a falling balance. Two retirements with the same average return can end very differently because of it, which is why holding some cash to draw on matters.