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Monte Carlo SWP

Markets don’t pay a steady return. This runs your withdrawal plan through a thousand bumpy markets and counts how often the money lasts.

Chance of success

29% chance your money lasts to 90

In 1,000 simulated markets averaging 10% a year with 15% swings, 29% never ran out. When it did run out, it was typically around age 80. With steady returns, it would run out at 87.

Shown in future amounts. Turn on Today’s money to adjust for 6% inflation.

Fragile: it depends on markets being kind. Lower the withdrawal or the yearly increase.

$
$
%
%
%
How much yearly returns swing. Roughly 15–20% for equity, 5–8% for a balanced fund.
yrs
yrs
%
Bad markets (10th pct)
$0
left at 90
Typical (median)
$0
left at 90
Good markets (90th pct)
$6.98M
left at 90

Range of outcomes

Median10th and 90th percentileFuture amounts

The spread between the lines is the uncertainty a single steady-return number hides.

Your age
Show the numbers as a table
Range of outcomes: data
Age10th pctMedian90th pct
60$1,000,000$1,000,000$1,000,000
61$855,860$1,025,265$1,217,836
62$786,843$1,064,378$1,373,945
63$751,137$1,080,211$1,488,030
64$725,151$1,093,038$1,636,545
65$696,618$1,107,649$1,730,097
66$646,255$1,122,252$1,846,461
67$600,477$1,114,672$1,965,366
68$542,583$1,134,508$2,179,645
69$481,594$1,118,039$2,299,353
70$401,829$1,112,879$2,457,596
71$315,676$1,098,924$2,621,087
72$220,702$1,074,424$2,732,693
73$107,556$1,044,608$2,910,379
74$0$1,008,113$3,090,907
75$0$955,766$3,207,360
76$0$883,752$3,422,520
77$0$770,301$3,758,924
78$0$655,358$4,015,397
79$0$516,262$4,238,872
80$0$396,424$4,446,431
81$0$211,112$4,653,264
82$0$22,613$5,015,212
83$0$0$5,005,565
84$0$0$5,141,007
85$0$0$5,545,404
86$0$0$6,032,754
87$0$0$6,135,522
88$0$0$6,442,841
89$0$0$6,796,994
90$0$0$6,976,069

Still going, by age

Your age
Show the numbers as a table
Still going, by age: data
AgeMoney left in
60100% of runs
61100% of runs
62100% of runs
63100% of runs
64100% of runs
65100% of runs
66100% of runs
67100% of runs
68100% of runs
69100% of runs
7099% of runs
7199% of runs
7297% of runs
7394% of runs
7489% of runs
7585% of runs
7681% of runs
7776% of runs
7871% of runs
7967% of runs
8061% of runs
8156% of runs
8251% of runs
8346% of runs
8443% of runs
8540% of runs
8637% of runs
8734% of runs
8832% of runs
8930% of runs
9029% of runs
How this is calculated

Each of the 1,000 runs draws a return for every year from a bell curve centred on 10% with a 15% standard deviation. That year’s return is applied month by month, after each withdrawal.

R = 10% + 15% × z, z ~ N(0, 1), floored at −95%
success = balance never hits 0 before 90

Runs are seeded, so a shared link shows the same result. “Run a different set of markets” changes the seed; the percentage moves a little because 1,000 runs is a sample.

Real returns have fatter tails than a bell curve and can trend for years, so treat this as a guide to robustness, not a forecast. Tax isn’t modelled.