Drawdown Analysis Calculator
The formula
What the drawdown analysis tells you
How long the money lasts: the drawdown analysis test runs the drawdown year by year with inflation-indexed withdrawals instead of a flat rule of thumb.
Calculation: Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year. Enter your inputs and every substitution is shown below the result.
Reading the result
Under 4 % historically survives 30-year retirements; over 6 % sequence risk dominates. The ending balance is the number to show a planner.
Rules of thumb: The 4 % rule (Bengen/Trinity) anchors US planning; index-linked variants suggest 3.25–3.75 % for 30+ year horizons.
Limitations and best practice
Deterministic math flatters itself — one bad decade at the start cuts real outcomes. Stress the return input at 0 % before trusting a pass.
This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Frequently asked questions
Does the drawdown analysis guarantee success?
Why index withdrawals to inflation?
Source & methodology
Trinity study / Bengen safe-withdrawal literature.
Drawdown Analysis explained: formula, worked example and honest limits
This page was written for one job: turning your own inputs into a defensible figure, with the working shown. There are plenty of pages about Drawdown Analysis; almost none of them show the working. This one does: the formula, every input, a fully computed example, and a sensitivity analysis calculated live from this engine’s own defaults.
Retirement math is a long game played with short inputs. Drawdown Analysis folds time, contributions and returns into Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year — and because time is the most powerful term, the inputs you control at the start matter more than heroics later.
In Retirement Planning the same quantity is often quoted under two or three different conventions. The formula printed above fixes one convention and applies it consistently, which is what makes results from this page comparable with each other.
What makes a calculation page trustworthy is that its copy is derived from its own arithmetic: here success over horizon = 100.0%, recomputed every time a field changes. Read the sections in order and you will be able to reproduce every figure by hand.
Inside the Drawdown Analysis calculation: formula and every input
Here is the complete model this tool runs — Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year — with each input explained below. If a competitor’s page gives you a different answer from the same inputs, this is the text that settles which of you is right.
Portfolio ($) (example value 965,097) is a measured number in the unit named by the label; the formula does not convert for you. Replace the example with the figure from your own records — the tool recomputes instantly and the printed steps follow your numbers.
Annual withdrawal ($) (example value 38,740) is a plain measured quantity — the unit shown in the label is the unit the formula expects. If you are unsure what belongs in this field, look at the printed steps: the substitution shows exactly how the engine uses it.
Expected return (%) (example value 5) is a measured number in the unit named by the label; the formula does not convert for you. Enter it exactly as your document states it — quoted annual, monthly and effective rates are three different numbers.
Inflation (%) (example value 3) is a plain measured quantity — the unit shown in the label is the unit the formula expects. Rates are the most mis-transcribed input on any page like this; copy it from the document rather than retyping from memory.
Horizon (years) (example value 29) is a measured number in the unit named by the label; the formula does not convert for you. Use the value as of today, not as of the last time you looked — time fields drift silently.
A fully worked Drawdown Analysis example
The tool prints its own working; this is the same arithmetic on the example values, reproduced so you can follow it by hand. Starting figures: Portfolio ($), Annual withdrawal ($), Expected return (%), Inflation (%). The computed success over horizon comes out at 100.0%, which the interpretation band labels “Standard band (the classic 4 % rule zone)”.
- Year-by-year: balance × (1 + 5.0%) − inflation-indexed withdrawal
- Start rate = $38,740.00 ÷ $965,097.00 = 4.01 %
- Portfolio survives the 29-year horizon with $765,219.29 left
Starting drawdown rate — 4.01%. If your inputs change, this is usually the first companion figure to move.
Ending balance — $765,219. Compare it against the main result of 100.0% before drawing conclusions.
Years funded — 29 yrs. This is the number experienced users quote when the headline alone would mislead.
Real purchasing power kept — 79.3%. Compare it against the main result of 100.0% before drawing conclusions.
Re-running with your own figures is instant; re-running by hand once is the best way to know the tool is telling you the truth.
Is your Drawdown Analysis good — reading the result bands
Nobody acts on a bare figure — they act on a figure with a comparison attached. The default case lands in the “Standard band (the classic 4 % rule zone)” band, and bands are deliberately wide because real situations overlap. The practical reading rules: ask what would have to change to move you one band. If the answer is “a small, plausible input difference”, the band itself is not the finding — the uncertainty is.
Related measures answer related questions, and the distinctions matter: Drawdown Analysis is the quantity, Success over horizon is this tool’s reading of it, and the decision that follows belongs to neither of them separately.
The errors that quietly break a Drawdown Analysis figure
Deterministic math flatters itself — one bad decade at the start cuts real outcomes. Stress the return input at 0 % before trusting a pass. This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Chasing precision in Annual withdrawal ($) while Portfolio ($) is still a guess. The sensitivity ranking above shows exactly where the accuracy budget should go.
A final trap is presentation: reporting Drawdown Analysis to more decimal places than the inputs support. The tool prints what the arithmetic gives; you should quote only what your least precise field justifies.
Before you trust your Drawdown Analysis: a short checklist
- State, in one sentence, which convention each rate, unit or period in the form is using.
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- Confirm the inputs are dated — a Drawdown Analysis figure should carry the date it was computed.
- Note the date and the inputs beside the number so the figure can be audited later.
- Record the date and the inputs alongside the number so future-you knows what was assumed.
- Repeat the ±10 % test on the inputs that matter and see whether the decision — not just the number — still holds.
Step by step: getting a trustworthy Drawdown Analysis out of this tool
Using a calculator well sounds trivial, but the difference between a decision-grade figure and a throwaway one lives entirely in the routine. The routine for Drawdown Analysis takes a minute to learn and applies to every input above.
Step 1 — start from evidence. The inputs behind Drawdown Analysis are portfolio ($), annual withdrawal ($), expected return (%), inflation (%), horizon (years). Write them down with their source next to each one; if you cannot name where a figure came from, that is the input most likely to be wrong. One decimal place more than your data supports is one decimal place of fiction.
Step 2 — enter the conservative case first. Resist the flattering scenario. Type the inputs you would defend in front of a sceptical reader, read the Success over horizon (100.0% for the example values), and note the verdict band. A figure nobody can reproduce is a figure nobody will act on twice.
Step 3 — play with the inputs on purpose. Ten percent up, ten percent down, one field at a time. Within a few minutes you will know this calculation better than most people who quote its results. Repeating a calculation with the same numbers proves only that the arithmetic is reliable — which is worth knowing.
Step 4 — stress before you commit. A decision that survives a ten-percent squeeze on its two biggest inputs needs no luck to be sound. One that does not survive is a decision about hope, not about arithmetic. Compare the calculation to the rough guess you arrived with, and ask why they differ.
Step 5 — record the context, not just the number. Note today’s date and the inputs alongside the 100.0% output. Six months from now the context is what turns this figure into a trend. Estimates improve most when the worst case is written down in ink.
Who actually uses Drawdown Analysis — and when
Most Retirement Income disagreements are arithmetic disagreements in disguise. When Success over horizon of 100.0% sits on the table with its working shown, the conversation stops being about who sounds more confident and starts being about which input is wrong. Repeating a calculation with the same numbers proves only that the arithmetic is reliable — which is worth knowing.
Professionals in Retirement Income use this style of calculation as a screening filter before spending real money or effort: a quick Drawdown Analysis check eliminates weak options in minutes, and the survivors earn the deeper, slower analysis. Write the figure down before moving on; memory flatters whichever number you saw last.
Nothing here is stored or transmitted, so the habit of checking is free: open the page, re-enter current figures, compare with the number you saved last time. Rounding early is the quietest way to introduce a permanent error.
Quick answers: what searchers ask about Drawdown Analysis
What is a typical Drawdown Analysis?
There is no honest universal average for Drawdown Analysis, but there is a reference point: the defaults on this page produce 100.0% (Standard band (the classic 4 % rule zone)). Replace the inputs with your own and compare — that comparison is the useful meaning of “typical”.
How do I calculate Drawdown Analysis by hand?
Three steps: write the formula (Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year), insert your values, and simplify. The worked example section shows exactly that chain for the default inputs; replicating it once on paper teaches you more about Drawdown Analysis than any number of calculator runs.
Is the Drawdown Analysis result of 100.0% good or bad?
Neither, on its own — the label “Standard band (the classic 4 % rule zone)” is the band this figure falls in for the example inputs, and your own inputs will place you elsewhere on the same ladder. Judge the number against your history and your alternatives.
What affects Drawdown Analysis the most?
Sensitivity depends on where you start, but the inputs Portfolio ($) and Annual withdrawal ($) typically move Drawdown Analysis further than the rest because they enter the formula multiplicatively. If you can only measure two things well, measure those and hold the others at conservative defaults.
How often should I check Drawdown Analysis?
Whenever an input changes by more than a few percent, and otherwise on the rhythm of your decisions — before a purchase, a review, a renewal. Drawdown Analysis is a snapshot, not a subscription; stale snapshots are the most common silent error in Retirement Planning planning.
Does the drawdown analysis guarantee success?
No — it answers the deterministic version of the question. Monte Carlo sequences change the odds, not the arithmetic.
Why index withdrawals to inflation?
A flat nominal withdrawal quietly shrinks real spending power; indexing keeps the standard of living constant, which is the honest test.
Is my data private on this page?
Yes — computation happens locally in your browser, with no account, no tracking of your inputs and nothing sent to a server. The printed formula is the whole story of what happens to your figures.
The vocabulary of Drawdown Analysis
- Starting drawdown rate
- 4.01% on the example inputs — a companion figure printed beside the headline of Drawdown Analysis so that no result is read in isolation.
- Ending balance
- $765,219 in the default Drawdown Analysis calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Years funded
- 29 yrs in the default Drawdown Analysis calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Success over horizon
- The primary output of this tool: 100.0% for the default inputs, computed exactly from Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year.
- Worked example
- Every substitution in order, from the example inputs to 100.0% — the audit trail for the headline figure.
- Verdict band
- A named zone on the range of plausible results; the example inputs land in “Standard band (the classic 4 % rule zone)”, and your inputs may not.
Where the Drawdown Analysis model comes from
Everything above runs on one stated formula, applied without hidden coefficients: Recursive drawdown: balance × (1+return) − withdrawal, with withdrawals inflation-adjusted each year. Source of record: Trinity study / Bengen safe-withdrawal literature. Any other implementation of this model should return the same figure for the same inputs. If one does not, the difference is in its assumptions — which this page prints and that one probably does not.
Nothing here replaces a qualified professional, and nothing here is approximate either — the arithmetic is exact, and the honesty is in the inputs you supply. Every intermediate value is printed so that the result can be checked line by line rather than accepted or rejected wholesale.
What to do with your Drawdown Analysis next
Save the number together with its inputs and today’s date; a Drawdown Analysis figure without context is unusable the moment an input changes.
Whoever you are (people who need one trustworthy number before their next decision), the next step is the same: replace the example inputs with your own, note the date, and re-run whenever a figure moves. In Retirement Planning, a dated figure is a trend, and an undated one is a rumour.