For FIRE planning, use your net savings rate: everything you save divided by your income after taxes. It measures the share of the money you actually control that you don’t spend, and that ratio sets both how fast your portfolio grows and how big it needs to be. Gross savings rate (savings divided by pre-tax income) is simpler and fine for comparing against rules like “save 15% for retirement,” but it understates how efficiently you live.
Either works if you use it consistently. The mistakes come from mixing the two, usually by dividing by take-home pay while forgetting the 401(k) money that never reached your bank account.
What’s the difference between gross and net savings rate? #
| Gross savings rate | Net savings rate | |
|---|---|---|
| Denominator | Total pay before taxes | Pay after all income and payroll taxes |
| Best for | Comparing with “save 15%” guidelines | Estimating your FIRE date |
| Easy to find? | Yes, on your W-2 or pay stub | Needs a little arithmetic |
| Downside | Counts tax money you never had | Easy to get wrong with pre-tax savings |
How do you calculate your savings rate? #
Gross savings rate formula #
Gross savings rate = total savings ÷ gross income
Total savings includes pre-tax 401(k) and HSA contributions, Roth contributions, taxable investing and cash you set aside.
Net savings rate formula #
Net savings rate = total savings ÷ (gross income − all taxes)
“All taxes” means federal, state and local income tax plus Social Security and Medicare (FICA). Subtract taxes from gross pay, not from your paycheck deposit. That way your pre-tax 401(k) contributions are counted in both the top and the bottom of the fraction, which is what keeps the math honest.
A worked example #
Sarah earns $120,000. Here’s her year:
- Taxes (federal, state, FICA): $24,000
- Traditional 401(k), pre-tax: $18,000
- HSA through payroll, pre-tax: $3,000
- Roth IRA: $7,000
- Taxable brokerage: $12,000
Her paycheck deposits total $75,000 ($120,000 minus taxes and the pre-tax contributions). After the Roth IRA and brokerage transfers, she spends $56,000.
- Total savings: $18,000 + $3,000 + $7,000 + $12,000 = $40,000
- Income after taxes: $120,000 − $24,000 = $96,000
- Net savings rate: $40,000 ÷ $96,000 = 41.7%
- Gross savings rate: $40,000 ÷ $120,000 = 33.3%
A quick sanity check: savings plus spending should equal after-tax income. $40,000 + $56,000 = $96,000.
The mistake to avoid #
If Sarah divided by her $75,000 of paycheck deposits but still counted her 401(k) and HSA as savings, she’d get $40,000 ÷ $75,000 = 53%. That overstates her rate, because $21,000 of the savings never passed through the $75,000. Always divide by income after taxes, not by what lands in your checking account.
Why net savings rate predicts your retirement date better #
Your time to financial independence depends on the ratio of what you save to what you spend. Net savings rate captures exactly that. At a 41.7% net rate, Sarah spends 58.3% of her after-tax income.
This table assumes you start from zero, earn 5% a year after inflation, and retire when your portfolio reaches 25 times your spending (a 4% withdrawal rate):
| Net savings rate | Years to financial independence |
|---|---|
| 10% | about 51 |
| 20% | about 37 |
| 30% | about 28 |
| 40% | about 22 |
| 50% | about 17 |
| 60% | about 12 |
| 70% | about 9 |
Sarah’s real 41.7% puts her at roughly 21 years. Plug her 33.3% gross rate into the same table and you’d get about 26 years, because the table would assume she spends $80,000 rather than $56,000. Five years of error from picking the wrong denominator. Our post on how your savings rate dictates your retirement date goes deeper into the curve.
One caveat: this math treats retirement spending as equal to today’s spending. If your savings sit mostly in pre-tax accounts, withdrawals will be taxed, so add an estimate of retirement taxes to the spending figure.
Common savings rate mistakes #
- Counting the employer match only on top. If you add your 401(k) match to savings, add it to income too. Our guide on factoring your employer 401(k) match into your savings rate shows the math.
- Mixing methods. Gross one month and net the next makes your trend meaningless.
- Counting mortgage principal inconsistently. It can count, but decide once. See whether paying off your mortgage counts toward your savings rate.
- Forgetting FICA. Social Security and Medicare taxes are taxes. Leave them out and your net income looks bigger than it is.
When the gross savings rate makes sense #
Gross isn’t wrong. It’s the better choice when you’re comparing yourself with a percent-of-salary guideline, when you want a number you can pull straight from a W-2, or when tax changes would otherwise make your year-to-year trend jump around. Just don’t feed a gross rate into a FIRE timeline built on net math.
From savings rate to a retirement date #
A savings rate tells you how fast you’re moving. It doesn’t tell you when you’ll arrive. Retire Goals doesn’t calculate your savings rate, but it turns the dollars behind it into a date: log each contribution to a goal and the projected finish date, growth curve and milestones update together. Its compound growth calculator shows how long a given monthly amount takes to reach your FIRE number, which is the question your savings rate is really answering.
Frequently asked questions #
Should I include my employer match in my savings rate? #
Yes, if you add it to both sides. Put the match in savings and in income. With $10,000 saved, a $3,000 match and $50,000 of after-tax income, the rate is $13,000 ÷ $53,000, or 24.5%.
What is a good savings rate for FIRE? #
Many people pursuing FIRE aim for a net savings rate of 50% or more, which works out to roughly 17 years from zero under the assumptions above. A 25% to 35% rate still gets most people to financial independence decades before a typical retirement age.
Do I subtract FICA taxes when calculating net savings rate? #
Yes. Subtract federal, state and local income taxes plus Social Security and Medicare taxes from gross pay. Don’t subtract pre-tax retirement or HSA contributions; those are savings, not taxes.
Does paying down debt count as savings? #
Paying principal on a mortgage or student loan raises your net worth, so some people count it. Interest never counts. The key is picking one rule and sticking with it so your savings rate stays comparable over time.