Retirement Savings Calculator

How this is calculated

Two things compound together here. Your existing balance grows on its own, and each monthly contribution grows from the moment it lands - so a contribution made 30 years out has 30 years to work and one made next year has one. THE FORMULA is the future value of a lump sum plus the future value of a series of payments: balance times (1 plus r) to the power n, plus contribution times ((1 plus r) to the n, minus 1) divided by r - where n is the number of months (years times 12) and r is the MONTHLY return, which is the annual rate divided by 12 and then by 100 - so 7 percent annual is 0.0058333 per month. Both conversions live inside the formula rather than beside it, because a formula and its glossary drift apart and the glossary is the part readers skip. ⚠️ THE SPLIT IS THE POINT. The calculator shows what you put in and what the growth added, separately, because the ratio between them is what actually argues for starting early. Over long periods the growth becomes the larger share, and it does so quite suddenly - that is what compounding looks like from the inside. TIME MATTERS MORE THAN AMOUNT, and by a wider margin than most people expect. Sweep the years input and watch: adding five years at the start of a working life typically does more than a substantial increase in monthly contribution, because those early contributions are the ones with the longest to grow. That is the single most useful thing this arithmetic can tell you. ⚠️ THE RETURN IS AN ASSUMPTION, NOT A FORECAST, and it dominates the answer. A percentage point either way over decades changes the result enormously, and nobody knows what the next thirty years will do. Long-run historical averages for broad stock markets are often quoted around 7 to 10 percent before inflation - but the sequence matters as well as the average, and real portfolios do not deliver a smooth number. ⚠️ THIS IS ALL IN NOMINAL DOLLARS. It does not adjust for inflation, and over 30 years that is a very large omission - money buys substantially less at the end than at the start. If you want a figure in today's purchasing power, enter a REAL return instead: roughly your expected return minus expected inflation. That gives a smaller and more honest number. WHAT IT DOES NOT MODEL: fees, which compound against you exactly as returns compound for you; taxes, which depend entirely on the account type and jurisdiction; irregular contributions; employer matching; and the sequence of returns, which matters a great deal near retirement. This is arithmetic on assumptions you supply. It is not financial advice, and a calculator cannot know your circumstances.

Common questions

Why show what I contributed separately?

Because the ratio between your money and the growth is the whole argument for starting early, and a single final number hides it completely. Over long periods the growth becomes the larger share - and it crosses over quite suddenly rather than gradually, which is what compounding actually looks like from the inside. Seeing the split is far more instructive than seeing the total.

Does time really matter more than the amount?

By a wider margin than most people expect, and the calculator is built to show it. The 'five more years' output exists for exactly this: compare it against your projected value and notice that the gap is far larger than the 60 extra contributions that produced it. The reason is that early contributions have the longest to grow, so years added at the START of a working life are worth much more than the same years added at the end.

Is 7 percent a reasonable return?

It is a common assumption rather than a fact, and it dominates the answer - a percentage point either way over decades changes the result enormously. Long-run historical averages for broad stock markets are often quoted around 7 to 10 percent before inflation, but nobody knows what the next thirty years will do, and the SEQUENCE of returns matters as well as the average. Treat this input as the assumption you are choosing to make, and try a lower one to see how much rests on it.

Why isn't inflation included?

Because including it would require guessing at a second unknown, and the honest fix is simpler. This shows nominal dollars, so over 30 years the final figure buys substantially less than the same number today. If you want a result in today's purchasing power, enter a REAL return instead - roughly your expected return minus expected inflation, so 7 percent expected and 3 percent inflation becomes 4. The number gets smaller and considerably more honest.

What is missing from this?

Several things that matter. Fees, which compound against you exactly as returns compound for you, and which a percentage point of over decades costs about what a percentage point of return gains. Taxes, which depend entirely on the account type and where you live. Employer matching, irregular contributions, and pauses. And the sequence of returns, which matters little at the start and a great deal near retirement, because a bad few years just as you begin drawing down does far more damage than the same years early on.

Is this financial advice?

No. It is arithmetic on assumptions you supply, and every one of those assumptions is doing more work than the formula is. It cannot know your circumstances, your tax position, your other assets, your risk tolerance or your plans. What it is genuinely useful for is comparing scenarios against each other - five more years against a higher contribution, one return assumption against another - because the RELATIONSHIPS it shows are far more reliable than any single figure it produces.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Retirement Savings Calculator at https://www.bfcbrilliance.com/tools/retirement-savings-calculator.

What I entered:
- What you have now ($): ___
- Added each month ($): ___
- Years until you need it (years): ___
- Assumed annual return (%): ___

What it calculated:
- Projected value: ___
- What you put in: ___
- What the growth added: ___
- Growth as a share of the total: ___
- Contributions alone: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Keep this general and do not give financial advice — flag where I should talk to a qualified adviser.

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