Savings Rate Calculator

Why savings rate is the lever

Most personal-finance advice focuses on income — earn more, get promoted, switch jobs, learn a high-paying skill. All sound advice. But the math of early retirement turns out to depend almost entirely on something else: the share of your income you actually save.

The reason is that savings rate compounds in two directions. Saving more means more capital flowing into your portfolio. It also means lower spending, which lowers your FIRE target — the number you need invested before you can stop working. A 4% withdrawal rate implies a 25× expense multiplier, so each $1k you trim from annual spending is $25k less you need to accumulate.

The result is the curve in the calculator above: a steep, almost cruel function of savings rate. At 5% savings, FIRE takes about 66 years. At 50%, it takes 17. At 75%, it takes 7. The difference between these scenarios isn't 10× — it's nearly 10× in time, which is the only thing that actually matters.

The math

From Pete Adeney's 2012 article "The Shockingly Simple Math Behind Early Retirement" . Closed-form, given starting balance of zero, constant real return r, savings rate s, and withdrawal rate w:

n = log(1 + (1/w) · r · (1 − s) / s) ÷ log(1 + r)

At w = 4%, that 1/w becomes 25 — the classic 25× expense multiplier. At r = 5% and s = 0.5, this gives n ≈ 17: 17 years from broke to financial independence.

Every percentage point of savings rate moves the date more than the rate of return does.

The canonical table (5% real return, 4% withdrawal)

These are the same numbers Pete published in 2012, and they haven't changed — because the math doesn't change. What changes is your starting position.

How to lift your savings rate

There are two levers — earn more, or spend less. Both work; one scales much better.

• Bank raises. The single most reliable way to raise your savings rate is to keep lifestyle flat as income rises. A 5% annual raise spent on a nicer apartment doesn't move savings rate. A 5% raise routed to investments lifts it every year.
• Audit recurring expenses. Subscriptions, insurance, vehicle costs, housing — these compound the same way savings do, but in the wrong direction. A $200/mo recurring expense costs $60k of FIRE number at a 4% rate.
• Pick lower-cost geography. Cost of living dwarfs almost every other lever. Moving from a high-COL metro to a moderate one can take a 25% saver to 50% overnight.
• Resist convenience spending. Delivery, paid parking, daily takeout. None of these individually look like real money; together they're the difference between 25% and 35% savings rate for a lot of people.
• Front-load investments. Max 401(k) and IRA contributions are a forcing function — money moved before you see it can't be spent. Most people who hit 50%+ savings have automated all of it.

What this calculator doesn't model

• Starting balance. The math assumes you start from $0. If you have meaningful investments already, your real years-to-FIRE is shorter — use Standard FIRE for that picture.
• Variable returns. Real markets don't return a constant 5%. The classic FIRE math averages this away; sequence-of-returns risk doesn't show up in the curve.
• Career changes. Salary jumps, sabbaticals, parental leave, business ventures — none of these are in the constant-savings-rate model.
• Taxes on the way out. The 4% rule is pre-tax. If most of your savings are in traditional accounts, your real FIRE number is 10–20% higher.
• Lifestyle inflation. If your savings rate drifts down as you age, your time-to-FIRE drifts up. The calculator's number is "if you keep doing what you're doing."