Coast FIRE Calculator for Married Couples
Free Coast FIRE Calculator for Married Couples. Calculate your Coast FIRE number with country-specific defaults, formulas, worked examples, and FAQs.
Your Numbers
Coast FIRE Achieved!
$71,432
is your Coast FIRE number. You already have enough!
Progress 119%
FIRE Nest Egg
$1,375,000
at retirement age
Coast Age
25
Already coasting!
Cash Freed
$12,000
per year from saving
Real Return
5.37%
after inflation
Growth Projection
Coast (no more saving) Keep saving Target nest egg
How to Use the Coast FIRE Calculator for Married Couples
To use the Coast FIRE calculator as a married couple, enter your joint finances and choose whose retirement date anchors the plan. The calculator returns your household's Coast FIRE number, and running it once for each spouse's retirement date shows how much your age gap changes the answer.
- Decide which spouse's timeline to use. For a cautious plan, use the older spouse, who retires first. For a plan where the younger spouse keeps working longer, use the younger spouse.
- Enter that spouse's Current Age and Retirement Age.
- Enter household Annual Spending in Retirement, minus both spouses' benefits. Use your joint budget and subtract both Social Security or pension amounts.
- Enter combined Current Invested Assets. Add both spouses' retirement and taxable accounts. Joint and individual accounts both count.
- Enter your combined Monthly contribution. Include both employer matches.
- Run the calculator a second time for the other spouse's timeline. Compare the two Coast FIRE numbers. Your real answer sits between them.
How to read your results
- Coast FIRE number: the joint balance you need invested today.
- Progress: how close your combined savings are to that number. Above 100% means you have already coasted.
- FIRE Nest Egg: the full joint portfolio needed at retirement.
- Coast Age: the anchor spouse's age when your household can stop saving.
- Cash Freed: the yearly saving both of you get back.
How the Coast FIRE Calculator for Married Couples Works
The calculator treats a married couple as one household with one nest egg, then discounts that nest egg back to today using your real return. The number of years you enter has the largest effect, which is why a spousal age gap matters.
The formula
FIRE Nest Egg = Joint Annual Spending ÷ Safe Withdrawal Rate
Real Return (r) = (1 + Growth Rate) ÷ (1 + Inflation Rate) − 1
Coast FIRE Number = FIRE Nest Egg ÷ (1 + r)^Years| Variable | Meaning | Unit |
|---|---|---|
| Joint Annual Spending | Household spending after both spouses' benefits | currency, today's value |
| Safe Withdrawal Rate | First-year withdrawal as a share of the joint portfolio | % |
| Growth Rate | Blended yearly return before inflation | % per year |
| Inflation Rate | Average yearly rise in prices | % per year |
| Years | Anchor spouse's Retirement Age − Current Age | years |
Worked example
Dana is 45 and Chris is 39. They spend $80,000 a year and expect $40,000 a year from Social Security combined, so their portfolio must cover $40,000. They hold $350,000 and save $1,200 a month together.
| Plan A: retire when Dana is 67 | Plan B: retire when Chris is 67 | |
|---|---|---|
| Years to retirement | 22 | 28 |
| FIRE Nest Egg | $1,000,000 | $1,000,000 |
| Growth factor at 3.88% real | 2.312 | 2.906 |
| Coast FIRE number | $432,490 | $344,109 |
| Progress | 81% | 102% |
| Coast Age | Dana at 52 | Already coasting |
Under Plan B, Dana and Chris have already reached Coast FIRE. Under Plan A, they need seven more years of saving. A six-year age gap moves their Coast FIRE number by $88,381.
Factors that change your result
- Survivor planning. When one spouse dies, the household loses the smaller Social Security benefit, but costs rarely drop by half. Test a higher spending input to build a survivor buffer. Raising Dana and Chris's spending gap to $52,000 lifts their Plan A Coast FIRE number to $562,237.
- Joint tax filing. Married couples filing jointly in the US get wider tax brackets, which lowers tax on retirement withdrawals. The calculator doesn't apply tax, so enter gross spending.
- Spousal accounts. A working spouse can fund a spousal IRA for a non-working spouse. A surviving spouse can roll an inherited IRA into their own.
- Rounding. Results are rounded to whole currency units, contributions are added yearly, and Coast Age is shown in whole years.
Coast FIRE Calculator for Married Couples FAQs
How do married couples with an age gap use the Coast FIRE calculator?
Run the calculator once with each spouse's age and retirement age. The older spouse's timeline gives fewer years of growth and a higher, safer Coast FIRE number. The younger spouse's timeline gives a lower number that assumes the money stays invested longer.
Do married couples need a bigger Coast FIRE number?
No, married couples usually need less than two single people combined. Shared housing and household costs lower joint spending, and two Social Security benefits cover more of the budget. The total nest egg is larger than one person's, but smaller than two.
What happens to our Coast FIRE plan if one spouse dies?
The surviving spouse keeps the larger of the two Social Security benefits, but the household loses the smaller one. Spending usually falls by much less than half. Add a buffer to your spending input, or hold life insurance until you reach your Coast FIRE number.
Should married couples file taxes jointly for Coast FIRE?
Most married US couples pay less tax filing jointly, which helps a Coast FIRE plan. Joint filing gives wider brackets for retirement withdrawals and allows spousal IRA contributions. The calculator doesn't apply tax, so plan withdrawals with your own tax situation in mind.
Can one spouse retire earlier than the other under Coast FIRE?
Yes, one spouse can stop work earlier while the other keeps earning. Set the monthly contribution to what the working spouse keeps saving, and anchor the timeline to your joint retirement date. The Coast Age result shows whether the plan still works.
Is the Coast FIRE calculator accurate for married couples?
The calculator is accurate for one shared timeline, but it doesn't model two separate retirement dates in one run. Running it for both spouses' dates gives you a realistic range. Recheck the plan after any big change, such as a new child, a job change, or an inheritance.