Retirement Savings Calculator

Estimate how much you'll have when you retire

Retirement planning starts with a simple question: if I save a certain amount each month, how much will I have when I stop working? This calculator gives you that number based on your current age, your target retirement age, your monthly savings, and the expected annual return on your investments.

How the calculation works

The formula for the future value of a regular monthly contribution is:

FV = PMT × [(1 + r)^n − 1] / r

Where PMT is the monthly payment, r is the monthly interest rate (annual rate ÷ 12), and n is the total number of months (years × 12).

This is the standard future value of an annuity formula. It assumes you make consistent monthly contributions and that returns compound monthly.

The power of time

Time is the most important variable in retirement savings. Starting earlier has a dramatically larger effect than increasing contributions later.

Example: Saving $500/month at 7% annual return:

• Starting at age 25 (40 years): $1,327,000
• Starting at age 35 (30 years): $600,000
• Starting at age 45 (20 years): $247,000

The person who starts at 25 accumulates more than twice as much as the person who starts at 35, despite only contributing for 10 more years.

What interest rate to use

The choice of expected return significantly affects the result:

• 5%: conservative estimate, appropriate for a bond-heavy portfolio
• 7%: the traditional rule of thumb for a diversified stock-and-bond portfolio (real, inflation-adjusted return)
• 10%: approximate historical nominal US stock market return (before inflation)

Using real returns (after inflation) makes the result easier to interpret in today's dollars. Using nominal returns requires discounting the result for future inflation.

What this calculator does not account for

This projection assumes a constant monthly contribution and a constant annual return, which is a simplification of real life. It does not model market volatility year to year, changes to your contribution amount over time, taxes on withdrawals, or additional income sources such as a state pension. Treat the result as a useful, order-of-magnitude estimate for planning purposes rather than a guaranteed outcome, and revisit the numbers periodically as your actual savings rate and investment returns become clearer over the years ahead.

Improving your retirement outcome

Several levers increase retirement savings:

• Start earlier: Every year earlier has a compounding effect.
• Save more: Even small increases compound significantly over decades.
• Optimize asset allocation: Higher equity allocation historically produces higher long-term returns, with higher short-term volatility.
• Reduce fees: Investment fees of 1–2% per year reduce retirement wealth by 20–40% over 30 years.
• Tax-advantaged accounts: 401(k), IRA, Roth IRA (US), ISA (UK), and similar accounts shelter growth from taxes.

How much do you need to retire?

A common rule of thumb is the 4% rule: you can sustainably withdraw 4% of your portfolio per year without running out of money over a 30-year retirement. So to spend $40,000 per year you need $1,000,000 saved. To spend $60,000 per year you need $1,500,000.

Use this calculator to estimate what you will have, then compare it to the 4% rule target for your desired annual spending.

How to use the calculator

Enter your current age, your target retirement age, how much you plan to save each month, and the annual return rate you expect from your investments. The projected balance at retirement appears immediately, and every figure recalculates the instant you change any input, which makes it simple to test how retiring five years later, saving a little more each month, or assuming a more conservative return would shift your outcome.

Why compounding rewards patience

The future-value formula behind this calculator is a compound interest calculation, and compounding is powerful precisely because each month's returns are calculated not just on your original contributions but on all the growth those contributions have already produced. In the early years of saving, this effect is barely noticeable — most of the balance is still your own contributions. But by the later decades of a long saving horizon, the accumulated growth itself starts generating more growth than your monthly contributions do, which is exactly why starting a decade earlier tends to matter more than saving twice as much per month starting later. There is no way to manufacture those extra years after the fact, which is the single strongest argument for starting to save as early as possible, even with a small amount.

Adjusting your plan as circumstances change

Few people set a savings amount once and leave it untouched for forty years — incomes rise, priorities shift, and a plan is only useful if it is revisited periodically. Because every field in this calculator recalculates instantly, it works well as a check-in tool: run your numbers once a year with your current age, current monthly contribution and a realistic return assumption, and compare the new projection with the previous year's. A small raise redirected entirely into retirement savings, or a decision to push the target retirement age back by a couple of years, both show up immediately as a changed final balance, which makes the trade-offs involved in each decision concrete rather than abstract.

Private and instant

All calculations run entirely in your browser using the standard future-value-of-an-annuity formula, so projections update instantly as you adjust any input and no financial figures you enter are ever sent to a server, logged or shared.