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A 50% savings rate gets you to FIRE in roughly 17 years. A 25% rate takes 32 years. A 75% rate takes 7 years. Your savings rate — the percentage of income you invest — determines your retirement timeline more than your salary, your investment returns, or which index fund you pick.
This is the single most important number in FIRE planning. Not your income. Not your investment strategy. Your savings rate.
| Savings Rate | Years to FIRE* | Monthly Savings on $5K Income | FIRE Number at $3K/mo Expenses |
|---|---|---|---|
| 5% | ~66 years | $250 | $900,000 |
| 10% | ~51 years | $500 | $900,000 |
| 15% | ~43 years | $750 | $900,000 |
| 20% | ~37 years | $1,000 | $900,000 |
| 25% | ~32 years | $1,250 | $900,000 |
| 30% | ~28 years | $1,500 | $900,000 |
| 35% | ~25 years | $1,750 | $900,000 |
| 40% | ~22 years | $2,000 | $900,000 |
| 45% | ~19 years | $2,250 | $900,000 |
| 50% | ~17 years | $2,500 | $900,000 |
| 55% | ~14.5 years | $2,750 | $900,000 |
| 60% | ~12.5 years | $3,000 | $900,000 |
| 65% | ~10.5 years | $3,250 | $900,000 |
| 70% | ~8.5 years | $3,500 | $900,000 |
| 75% | ~7 years | $3,750 | $900,000 |
| 80% | ~5.5 years | $4,000 | $900,000 |
| 85% | ~4 years | $4,250 | $900,000 |
| 90% | ~2.5 years | $4,500 | $900,000 |
*Assumes 7% real return, 4% SWR, starting from $0 saved. Existing savings shorten the timeline. Run your exact numbers with your actual savings.
Income is misleading. Three people with the same $100K salary can be in completely different positions:
| Person | Salary | Expenses | Savings Rate | FIRE Number | Years to FIRE |
|---|---|---|---|---|---|
| Person A | $100K | $90K | 10% | $2,250,000 | 51 years |
| Person B | $100K | $60K | 40% | $1,500,000 | 22 years |
| Person C | $100K | $35K | 65% | $875,000 | 10.5 years |
Same income. Person C reaches FIRE 40 years before Person A. The difference is entirely about spending.
This cuts both ways. If someone earning $50K has a 50% savings rate ($25K expenses), their FIRE number is $625,000 and they reach it in ~17 years. They retire before Person A earning twice as much. This is why the FIRE community focuses on savings rate, not income level.
The formula:
Savings Rate = (After-Tax Income - Total Expenses) ÷ After-Tax Income × 100
Example: $6,000 after-tax monthly income, $3,200 monthly expenses.
Savings = $6,000 - $3,200 = $2,800
Savings Rate = $2,800 ÷ $6,000 × 100 = 46.7%
Plug these numbers directly into the FIRE calculator — it computes your savings rate automatically and shows your FIRE number and timeline.
Not all savings rate increases are created equal. The biggest year-reduction per percentage point is in the 20-50% range:
The first 20 percentage points (10% → 30%) save roughly 23 years. That is the sweet spot of effort vs. impact. After 50%, each additional point has diminishing returns on time saved and requires increasingly extreme lifestyle changes.
Sorted by impact (largest expense categories first):
The single biggest lever. Options: get a roommate ($500-800/month savings), move to a lower-cost area, house hack (buy a duplex, live in one unit, rent the other), or negotiate rent at lease renewal. Saving $500/month on housing adds $6,000/year to savings and reduces your FIRE number by $150,000.
The second biggest lever. Options: drive a paid-off car instead of financing, switch to one car for a couple, use public transit, bike commute. The average American car payment is $738/month — eliminating that adds nearly 15 percentage points to a $5,000/month income savings rate.
Cooking at home saves roughly $500-700/month versus regular restaurant meals. Meal prepping on Sundays eliminates the "too tired to cook" takeout orders that blow up food budgets.
If cutting expenses is hard, growing income while keeping expenses flat achieves the same result. A $1,000/month raise with no lifestyle inflation adds 20 percentage points to the savings rate of someone earning $5,000/month. Job hopping every 2-3 years is the most reliable way to increase salary — average raises for switching are 10-20%, versus 3-5% for staying.
See how your savings rate affects your retirement date.
Calculate Your Timeline →This is the most powerful concept in FIRE math and it bears repeating: every dollar cut from expenses does two things simultaneously.
Cutting $200/month in expenses: adds $2,400/year to savings AND reduces FIRE number by $60,000. No investment return or salary increase provides that kind of double benefit. This is why the FIRE community emphasizes frugality alongside income growth — it is literally twice as effective, dollar for dollar.
To model exactly how cutting expenses accelerates your compound growth, use our compound interest calculator with the increased monthly contribution. For the full FIRE number calculation with all variables, the FIRE calculator handles it in one step.