Understand your money well enough to argue with us.
Most personal finance is either a calculator with no explanation or an explanation with no calculator. Ledgerwise pairs working tools with the research behind them, so you end up with a plan you can defend — including to yourself, at the moment the market is falling and the plan stops feeling good.
No account needed. Everything works anonymously — sign in only when you want your plan saved across devices.
- working tools
- 12
- years of market data
- 97
- evidence notes
- 15
- cited sources
- 27
working tools
years of market data
evidence notes
cited sources
Calculators that use your numbers
One profile feeds every tool. Change your income once and the emergency fund, the debt comparison and the retirement target all move together, because in real life they do.
Simulators that run on real history
Sequence risk, market timing and the cost of averaging in are tested against every starting year since 1928 — not a smooth average that never happened to anyone.
Arguments with citations attached
Every claim links to the study behind it, the size of the effect, and the conditions under which it stops being true. A finding without its caveats is marketing.
12 tools, in the order the arithmetic puts them
The sequence is not a matter of taste. Each step is placed by the certainty-adjusted return of the money that flows into it — which is why an employer match comes before clearing a credit card, and a cash buffer comes before an index fund.
Foundations
The steps that come before investing, in the order the arithmetic puts them.
Building wealth
Contributions, costs and what to own.
Retirement and drawdown
Targets, ranges, and the risk of a bad decade.
Decisions under uncertainty
The gap between what portfolios return and what investors earn.
You already know to buy and hold. The question is whether you will.
The best-measured finding in retail investing is that investors earn less than the funds they own, because of when they buy and sell. Reading that changes nothing. So the decision simulator drops you into twenty years of real market history with the dates hidden, lets you allocate each year, and then prices exactly what your reactions cost against simply holding.
Play a runMonte Carlo projection
What is the range of outcomes, not just the average?
Sequence risk explorer
What if I retire into a bad decade?
Lump sum vs averaging in
I have a windfall. All at once, or spread out?
The cost of being out
What does missing the best years cost?
The decision simulator
How would I actually behave in a crash?
The five periods every plan has to survive
Each bar is one calendar year of US stock returns after inflation. Any plan built on an average return is really a bet that you would have sat through all of these — so the tools test against them rather than around them.
The Great Depression
1929–1938- Worst year
- -38%
- Whole period
- +2%
Stocks fell for four straight years and lost roughly 80% peak to trough. Deflation meant real losses were smaller than nominal ones — the only time that has helped.
The 1970s
1966–1982- Worst year
- -33%
- Whole period
- -1%
Nominally, stocks roughly broke even. In real terms this was a 16-year loss. The decade that proves nominal returns can flatter a disaster.
The lost decade
2000–2009- Worst year
- -39%
- Whole period
- -29%
A negative total return for US stocks across ten calendar years, bracketed by two 45%+ drawdowns. Bonds carried the balanced investor.
The global financial crisis
2007–2013- Worst year
- -39%
- Whole period
- +31%
A 37% single-year fall, then a full recovery within about four years for anyone who held on and kept contributing.
2022
2021–2024- Worst year
- -24%
- Whole period
- +37%
Stocks and bonds fell together, the failure mode a 60/40 portfolio is not supposed to have. Diversification is not a guarantee.
- Open sequence risk →
Run your own numbers through them
The sequence risk tool replays every 97-year record starting point against your withdrawal plan, and reports the ones that failed rather than the average that did not.
The evidence library
15 notes covering the findings this whole product rests on. Each states a falsifiable claim, rates how strong the evidence actually is, and lists the conditions under which it fails.
Fees are the most reliable predictor of returns you control
A one percentage point difference in annual cost compounds into roughly a fifth of a portfolio's final value over a working life. It is the one input that is known in advance.
2 citationsMost active funds underperform, and past winners rarely repeat
The question is not whether skilled managers exist. It is whether you can identify them in advance, and whether their skill exceeds their fee. The evidence on both is discouraging.
2 citationsInvestors underperform the funds they own
The gap between fund returns and investor returns is the cost of decisions. It is the largest avoidable drag most people face after fees.
3 citationsMarket timing requires being right twice, and the good days cluster in the bad times
The familiar statistic is true but incomplete. The real argument against timing is not that returns concentrate — it is that exiting and re-entering are two separate correct calls, and the second is the one nobody makes.
2 citationsMost individual stocks lose money; a few pay for everything
Positive market returns coexist with most individual stocks losing money, because returns are extremely skewed. This is the strongest argument for owning the whole market rather than a selection of it.
2 citationsBuilding a plan on US returns is a bet, not a neutral assumption
Nearly every retirement calculator, including the historical simulator on this site, runs on US data. That is a choice with consequences worth naming.
1 citation