Definition
Your burn rate is the speed at which money leaves your accounts — the dollars per year (or per month) you actually spend. The term is borrowed from startups, where "cash burn" measures how fast a company is consuming its funding and runway measures how long the money lasts at that pace. A household living off its savings is the same arithmetic pointed at a person: the nest egg is the funding, the spending is the burn, and the years remaining are the runway.
Two versions of the number matter, and they are easy to mix up:
- Gross burn — everything you spend in a year. Housing, food, insurance, healthcare, taxes, travel, gifts, the new water heater. Every dollar out, no matter where it came from.
- Net burn — gross burn minus the income that arrives on its own: Social Security, a pension, dividends and distributions, rent, part-time work. What remains is the amount your portfolio has to produce, usually by selling something.
Net burn is the number that actually stresses a portfolio, and runway falls straight out of it:
Runway (years) = portfolio ÷ net burn
A $700,000 portfolio against a $28,000 net burn has 25 years of runway — meaning 25 years *if the portfolio never grows and the burn never changes*. Both of those assumptions are wrong, in opposite directions, which is why runway is a sanity check rather than a forecast. It is still the fastest honest read you can get on where you stand.
The same two inputs, divided the other way, give you a percentage:
Burn rate as a percentage = net burn ÷ portfolio
That percentage is the same quantity the 4% rule calls a withdrawal rate. The difference is which end you start from. The 4% rule fixes the rate and solves for the spending you are *allowed*; burn rate measures the spending you *have* and solves for the rate you are actually running. Same equation, read in opposite directions — and the burn-rate direction is the one that matches how people really live, because spending is a fact about your life before it is a variable in a formula.
Why It Matters
Nearly every retirement guideline you will encounter — the 4% rule, guardrails, the "25× your expenses" shorthand — quietly assumes you already know your burn rate. It is the input, not the output. Yet most people can recite their portfolio balance to the dollar and have no idea what they spend in a year beyond a rough guess. The result is a plan built on a number nobody measured.
Burn rate also happens to be the input you can control. You cannot control market returns, the order those returns arrive in, or inflation. You can control spending. And a dollar cut from the burn rate does double work: it is a dollar you do not withdraw this year, *and* it lowers the portfolio you needed in the first place — at a 4% rate, by roughly $25. Trimming $4,000 a year of spending is worth about $100,000 of nest egg you never had to save. No investment decision available to an ordinary saver has that kind of leverage.
There is a risk dimension too. Net burn is what determines whether a bear market can force you to sell. A household whose income covers most of its spending sells little or nothing in a downturn; a household with a large net burn is liquidating shares at depressed prices, which is the exact mechanism behind sequence-of-returns risk. Two retirees with identical portfolios and identical gross spending can face completely different risk simply because one of them has $10,000 of net burn and the other has $45,000. This is also why an income floor works: it does not reduce what you spend, it reduces what the *market* has to fund.
Finally, the number converts an abstraction into a horizon. "I have $700,000" is a fact with no meaning attached. "I have 25 years of runway, and I am 62" is a decision you can act on.
How to Measure Yours
Burn rate is a measurement, not a budget. A budget is what you intend to spend; a burn rate is what actually left your accounts. Only one of those is useful for planning, and it is not the optimistic one.
- Pull twelve months of statements. Every checking account, every credit card. Twelve months, not one month multiplied by twelve — a single month misses the lumpy expenses that typically account for a meaningful slice of the year.
- Total the outflows, then remove the double-counts. Credit-card payments made from checking are not spending on top of the card charges; transfers between your own accounts are not spending at all. Count each dollar once, at the point it left for good.
- Add the lumps you have not paid yet. Property tax, annual insurance premiums, deductibles, a car every ten years, a roof every twenty. Divide each by the years between occurrences and add that annual slice, even in a year you did not pay it.
- Adjust for the retirement version of your life. Some spending stops, some starts.
| Usually falls or stops | Usually rises or starts |
|---|---|
| Payroll taxes, retirement contributions | Health insurance before Medicare |
| Commuting, work clothes, work lunches | Out-of-pocket healthcare, dental, vision |
| Mortgage, once it is paid off | Travel and hobbies in the early years |
| Supporting children | Home and yard services later on |
- Count taxes as spending. This is the step most often skipped. Money withdrawn from a traditional IRA or 401(k) is ordinary income, so funding a $60,000 lifestyle may require a $72,000 withdrawal. Qualified dividends and long-term gains are taxed more gently, and Roth withdrawals not at all — which is why tax-efficient income investing shows up directly in your burn rate rather than in some separate ledger.
- Subtract your automatic income to get net burn. Social Security, pension, annuity, dividends, rent. Whatever is left is what the portfolio must cover.
A reasonable practice is to redo this once a year. Spending drifts, and the version of the number you measured before you retired is not the version you are living now.
Example
Every figure below is illustrative — invented to show the structure, not a projection of anyone's actual results.
Consider a 62-year-old with a $700,000 portfolio. Twelve months of statements, plus amortized lumpy costs and estimated taxes, come to $72,000 of gross burn — $6,000 a month. Social Security pays $30,000 a year, and the portfolio's dividends and distributions throw off about $14,000.
| Line | Annual | Monthly |
|---|---|---|
| Gross burn — everything spent, taxes included | $72,000 | $6,000 |
| − Social Security | −$30,000 | −$2,500 |
| − Dividends and distributions | −$14,000 | −$1,167 |
| Net burn — what the portfolio must fund | $28,000 | $2,333 |
Now run the same portfolio through both versions of the number and watch the story change completely:
| Measure | Calculation | Result |
|---|---|---|
| Gross burn as a % of portfolio | $72,000 ÷ $700,000 | 10.3% |
| Runway on gross burn alone | $700,000 ÷ $72,000 | 9.7 years |
| Net burn as a % of portfolio | $28,000 ÷ $700,000 | 4.0% |
| Runway on net burn | $700,000 ÷ $28,000 | 25 years |
Same household, same month, same statements. Measured one way it looks about a decade from broke; measured correctly it is sitting almost exactly on the 4% rule with a 25-year runway before a single dollar of growth is counted. The gap between the two rows is entirely Social Security and dividend income doing their job, and it is why gross burn on its own is a misleading number to carry around.
Turn your own figures into a portfolio target — enter your net burn as the annual spending:
Two practical notes on the income side of that table. First, the $14,000 is only a genuine offset if it keeps arriving; a payout funded largely by return of capital is your own principal coming back, which lowers net burn on the spreadsheet while quietly shrinking the portfolio that has to last. A fund advertising a headline distribution rate well above the market — a covered-call fund like JEPI, say — deserves that check before you subtract its income from your burn. Second, many retirees hold one to two years of *net* burn in T-bills or a T-bill fund such as SGOV, so a bad market never gets a vote on the grocery budget. At $28,000 of net burn, that buffer is $28,000–$56,000 — a far smaller and more achievable number than the gross-burn version, which is another practical reason to know which one you are working with.
Why Burn Rate Is Not Flat
A single number is a starting point, not the whole picture, because burn rate moves over a retirement in two distinct ways.
Inflation lifts it. At 3% inflation, $72,000 of spending becomes about $96,800 in ten years and $130,000 in twenty. That sounds alarming until you notice the income side moves too. Social Security carries a cost-of-living adjustment, and a dividend-growth fund such as SCHD has historically raised its payout over time. Assuming a 3% COLA and 5% annual distribution growth — illustrative assumptions, not promises:
| Gross burn | Social Security | Dividend income | Net burn | |
|---|---|---|---|---|
| Today | $72,000 | $30,000 | $14,000 | $28,000 |
| Year 10 | $96,800 | $40,300 | $22,800 | $33,600 |
| Year 20 | $130,000 | $54,200 | $37,100 | $38,700 |
Gross burn rises 81% over the twenty years; net burn rises 38%. Inflation-linked and growing income absorbs most of the increase, and the portfolio's job grows far more slowly than the grocery bill does. That is the real argument for holding growing income rather than a fixed payout — it is defense against your own burn rate. It also fails if the growth does not materialize, which is why portfolio income stability matters more than a headline yield. For the general point that a rising cost of living eats a fixed payout, see nominal vs real yield.
Life bends it. Actual retirement spending tends not to march upward in a straight line. Researchers describe a "go-go, slow-go, no-go" pattern: heavy travel and activity early, tapering through the seventies, then a late-life rise as healthcare and support services take over from discretionary spending. Real spending often dips in the middle decades even as prices rise. The takeaway is not to model every wrinkle — it is to avoid over-trusting a single flat projection thirty years out, and to re-measure as you go.
Common Mistakes
- Budgeting instead of measuring. A budget is a plan and plans are optimistic. Twelve months of statements will usually come in above the number you would have guessed, and the gap is the whole reason to do the exercise.
- One month times twelve. Insurance, property tax, holidays, car repairs, and medical bills do not distribute themselves evenly across the calendar. A clean month extrapolated to a year understates the burn, sometimes badly.
- Leaving taxes out. Withdrawals from tax-deferred accounts are taxable income, and once required minimum distributions begin they are not optional. A burn rate that ignores the tax bill is not a burn rate.
- Comparing gross burn to the 4% rule. The 4% rule describes the portfolio-funded share of spending. Holding gross burn up against it makes a perfectly sound plan look like a crisis — exactly the 10.3% versus 4.0% confusion in the example above.
- Treating runway as a forecast. Portfolio ÷ net burn assumes zero growth *and* zero inflation. Those errors point in opposite directions and do not reliably cancel. Use runway as a quick read, and use a Monte Carlo simulation when the answer actually needs to be right.
- Only cutting spending once trouble arrives. Deciding what to trim during a 30% drawdown is the worst possible time to decide. Guardrails set the thresholds and the cuts in advance, while you are calm.
- Assuming income can substitute for measurement. Living on dividends does not exempt you from knowing the number — it just means you are checking whether income covers burn rather than how fast the balance drains. That comparison is the whole subject of can you live off dividends.
FAQ
What is a burn rate in personal finance?
A burn rate is how fast money leaves your accounts — total spending measured per year or per month. The term comes from startups, where cash burn describes how quickly a company consumes its funding. Applied to a household living off savings, it is the figure that determines how long the money lasts: portfolio divided by burn rate gives you runway in years. Unlike a budget, which describes what you intend to spend, a burn rate is measured from what actually left your accounts over the past twelve months.
How do I calculate my burn rate?
Add up twelve months of real outflows from every checking account and credit card, removing transfers between your own accounts so no dollar is counted twice. Add an annual slice of the irregular costs you did not happen to pay this year — property tax, insurance, a car every decade, a roof every two — and include income taxes, since a withdrawal from a traditional IRA is taxable. That total is your gross burn. Subtract Social Security, any pension, and your dividend and distribution income to get net burn, the amount your portfolio must actually produce.
What is the difference between gross and net burn rate?
Gross burn is everything you spend; net burn is gross burn minus the income that arrives without selling anything. The distinction matters because only net burn draws on the portfolio. In the worked example above, $72,000 of gross burn against a $700,000 portfolio looks like a 10.3% withdrawal rate, while the $28,000 net burn that remains after Social Security and dividends is 4.0% — the same household reading as either a crisis or a textbook plan depending on which number you use.
Is burn rate the same as a withdrawal rate?
They are the same quantity approached from opposite ends. A withdrawal rate is chosen — the 4% rule sets the percentage and tells you what you may spend. A burn rate is measured — you total what you spend and divide by the portfolio to see what percentage you are actually running. Comparing the two is the point: if your measured net burn is 3.2% of the portfolio, you are spending below the classic guideline; if it is 6%, the plan needs either a larger portfolio, more income, or less spending.
What is a good burn rate in retirement?
There is no universal figure, because the answer depends on the portfolio behind it and the years it must cover. As a rough orientation, a net burn near 4% of the portfolio lines up with the traditional guideline for a roughly 30-year retirement; below 3% is conservative, and above 5% carries real shortfall risk unless you have flexibility built in. What matters more than hitting a target number is knowing yours and checking it against your own horizon, income sources, and willingness to adjust spending when markets misbehave.
How does dividend income change my burn rate?
Dividends and distributions do not change gross burn at all — you spend what you spend. They reduce net burn, because every dollar of income is a dollar you do not have to raise by selling shares. That is why a retiree with substantial dividend income can withstand a downturn better than one with the same portfolio and no income: fewer shares are sold at depressed prices. The caveat is that the income has to be real and durable. A payout composed largely of return of capital hands back your own principal, which flatters net burn on paper while shrinking the asset that funds it.
How much cash should I hold against my burn rate?
A common approach is one to two years of net burn in short-term Treasuries, a T-bill fund such as SGOV, or a money market fund, so that near-term spending never depends on selling equities into a bad market. Sizing it against net rather than gross burn keeps the buffer realistic: at $28,000 of net burn, one to two years is $28,000–$56,000 rather than the $72,000–$144,000 the gross figure would imply. Holding much more than that has a cost, since cash reserves lag inflation over long stretches — see income floor for the structured version of this idea.
