Decision Tools
Seventeen free, interactive calculators that turn the data into a decision - from planning your money to sizing a bet. The money tools use proper statistics: geometric (compound) returns, Monte Carlo percentile ranges instead of a single fake line, real vs nominal dollars, and sourced long-run assumptions you can override. Everything runs live in your browser. Informational only, not financial advice.
Money & planning
Decision-grade calculators for the macro picture: what your money becomes, what it's worth after inflation, and how much risk you're taking.
Investment growth projection (Monte Carlo)
Project savings forward as a probability cone, not a single optimistic line. Runs thousands of simulations with realistic volatility and shows the 10th, 50th and 90th percentile outcomes in today's dollars.
Investment Growth Projection (Monte Carlo)
Median outcome: $215,135. Range $111,490-$449,983 (10th-90th percentile), in today's dollars. You contribute $160,000 over 25 years; the median path adds $55,135 of investment growth on top.
How to read this
We report the median, not the mean. Terminal wealth is lognormally right-skewed, so a few lucky paths drag the average above the typical outcome - the median is the honest middle. Volatility also imposes a drag: the compound return you actually realise is roughly your average return minus half the variance, so a higher volatility input lowers the median even at the same expected return. All figures are deflated into today's dollars, so they reflect real purchasing power. This is a probabilistic cone of 80.0% of simulated outcomes, not a guarantee; the true range is wider. Informational only, not financial advice.
Retirement & safe withdrawal
Will the money last? Enter your portfolio and spending; a Monte Carlo run reports the survival rate and how it compares to the 4% rule, the conservative forward-looking rate, and a valuation-aware (CAPE) rate.
Retirement & Safe Withdrawal (Monte Carlo)
Expect to cut spending - only 73% of paths last the full horizon. Below 75% your starting rate is high; plan to spend less, work longer, or save more.
Safe-withdrawal reference rates
| Method | Rate | Basis |
|---|---|---|
| Morningstar 2025 | 3.70% | Fixed-real, 30yr, 90% success, forward CMAs |
| Trinity / Bengen 4% | 4.00% | Classic historical anchor |
| Bengen 2025 SAFEMAX | 4.70% | Historical, 7 asset classes |
| FIRE (long horizon) | 3.25% | 40-50yr retirements |
| CAPE-aware (CAPE 39) | 3.03% | 0.0175 + 0.5 / CAPE - lower when valuations are stretched |
Your implied rate of 4.00% is above the CAPE-aware rate but within the classic 4% rule. Valuations matter: with the Shiller CAPE near 39, forward returns are likely below the long-run average, so a valuation-aware starting rate (~3.0%) is more conservative than the historical 4% rule. The headline rate is method-dependent - this shows the spread, not one "right" answer. Informational only, not financial advice.
Inflation & purchasing power
What today's dollars are really worth over time, and the real (after-inflation) return on an investment - using the Fisher equation, not a naive subtraction.
Inflation & Purchasing Power
In 20 years at 2.5% inflation, $1,000 buys what $610 buys today - a 39% loss of purchasing power.
Real (inflation-adjusted) return
7.0% nominal at 2.5% inflation is 4.39% real - by division, not subtraction. Subtracting gives 4.5%, which overstates your real gain.
CPI vs PCE - which inflation number?
CPI (FRED series CPIAUCSL) is a fixed-basket Laspeyres index and runs roughly 0.3-0.5 percentage points hotter than the Fed's preferred PCE price index (FRED series PCEPI), which lets the basket shift as people substitute. The Fed targets 2% PCE, not CPI. The official BLS inflation calculator uses CPI-U NSA (not seasonally adjusted).
Use a higher rate (~2.5%+) when budgeting against everyday prices; use ~2% when reasoning about Fed policy. Informational only - not financial advice.
Portfolio risk & Sharpe
Mix stocks, bonds and cash and see the expected return, volatility, Sharpe ratio and a realistic bad year - with diversification handled through the full covariance, not a naive average.
Portfolio Risk & Sharpe
Sharpe 0.30 - weak risk-adjusted return for a long-only mix. You are taking on volatility without much reward over cash. Remember correlations rise toward 1 in a crash, so a real bad year can be worse than the modeled 1-in-20 downside.
Assumptions used (long-run nominal)
| Asset class | Return / yr | Volatility |
|---|---|---|
| US stocks (S&P 500) | 9.5% | 18.5% |
| US 10-yr Treasuries | 4.7% | 10.0% |
| Cash / T-bills | 4.0% | 3.0% |
These are long-run historical figures (Damodaran / Dimson-Marsh-Staunton); forward estimates are lower. Risk is not symmetric: a 50% drawdown needs a +100% gain just to recover. Informational only, not investment advice.
Dollar-cost averaging vs lump sum
Invest it all now or spread it out? Simulated head-to-head with idle cash correctly earning the T-bill yield - the comparison most calculators get wrong.
Dollar-Cost Averaging vs Lump Sum
Lump sum wins 52% of the time here. Vanguard found lump-sum beats DCA roughly two-thirds of the time historically, because markets rise more often than they fall - so cash on the sidelines usually forfeits the risk premium. DCA still earns its keep as a behavioral hedge: it narrows the spread of outcomes and softens the regret of buying in right before a drop.
Read this before you decide
The cash yield is load-bearing: while DCA waits to deploy, the idle money here earns the T-bill rate (default 4.5%), not 0%. With cash paying that much, DCA's drag is smaller than the old "you lose the whole sidelined return" framing suggests - but the risk premium still usually wins. This assumes you ALREADY hold the lump sum and are deciding how to deploy existing cash, NOT investing new income as it arrives (paychecks naturally dollar-cost average and that math is different). Informational only - not investment advice.
Mortgage & rent-vs-buy
Monthly payment, total interest and the payoff effect of extra principal - plus an honest rent-vs-buy break-even that charges opportunity cost on both sides and counts only mortgage interest as a cost.
Mortgage & Rent-vs-Buy
Add an extra monthly principal payment above to see the payoff and interest savings.
At 7 years, renting is cheaper — buying nets $157,434 vs renting $154,219. Overall, buying is cheaper if you stay longer than ~8 years.
How to read this
Mortgage principal is not a cost — it converts cash into home equity, so only interest, taxes, maintenance, insurance and the opportunity cost of your tied-up cash count against buying. Transaction costs (buy + sell closing) are the reason a break-even exists: you have to live somewhere long enough to out-earn the round trip. Both sides are charged the same 5.0% opportunity-cost rate so the comparison is fair.
Rate reference: FRED MORTGAGE30US (~6.5%, 2026). Note the 2026 standard deduction means most homeowners don't itemize, so this model deliberately does notover-credit the mortgage-interest deduction. Informational only — not financial advice.
Markets & betting
Tools for trading the odds themselves - bet sizing, edge-finding, cross-venue arbitrage, and the macro models behind the MacroOdds Signal.
Size the bet: Kelly criterion
The math for how much to stake. Enter your probability and the market price; get the growth-optimal bet size, capped for safety. Defaults to the live Fed-cut price.
Kelly Bet Sizer
Bet YES - stake $250.00 (25.0% of bankroll, ~25000 contracts), capped at 25% for safety
Why fractional Kelly
| Kelly multiple | P(double before halve) | Relative growth |
|---|---|---|
| Quarter (0.25x) | 0.96 | 0.44 |
| Half (0.5x) | 0.89 | 0.75 |
| Full (1.0x) | 0.67 | 1.00 |
| Double (2.0x) | 0.50 | 0.00 |
Full Kelly maximises long-run growth but swings hard. Half-Kelly keeps ~75% of the growth with far smaller drawdowns - the standard choice. Double Kelly grows nothing while risking everything.
Expected value & edge
Enter your own probability and the market price to see whether a bet has positive expected value.
EV / Edge Calculator
Positive expected value - you have an edge
Blend the sources into one signal
Pool Polymarket, Kalshi and CME FedWatch into a single consensus probability using log-odds weighting - the method that scores best on forecast accuracy.
Multi-Source Signal Blender
Weighted log-odds pooling - the method that scores best on forecast accuracy. Weight each venue by how much you trust it (volume is a good proxy). Keep the confidence boost modest: Polymarket, Kalshi and FedWatch all read the same futures, so they are correlated, not independent.
Strip out the vig
Prices across mutually-exclusive buckets sum to more than 100%. Remove the overround to get true, normalised probabilities before you trust any single number.
Vig Remover (de-vig)
Raw market prices across mutually-exclusive buckets sum to more than 100% - that excess is the vig. The true-odds column strips it out so the probabilities sum to exactly 1. Use this before trusting any single bucket number.
How much to trust a price
A thinly-traded price is a noisier estimate. This Wilson confidence interval shows the plausible range for the true probability - useful for telling a real edge from noise.
Price Confidence Interval
A thinly-traded price is a noisier estimate than a deeply-traded one. This Wilson band shows the range the true probability plausibly sits in - if two venues' bands overlap, an apparent edge may just be noise. Use trade count, not dollar volume, for the sample size.
Fees & break-even
What Kalshi and Polymarket actually charge per contract, and the price your bet has to clear to make money. Polymarket is no longer free.
Fee & Break-Even Calculator
Both venues charge most at the 50c midpoint and almost nothing on lopsided contracts. Your edge has to clear the break-even price to make money. Polymarket is no longer free - factor it in.
Cross-venue arbitrage
When two venues quote the same event, a price gap can be risk-free profit. This finds it and splits your capital so both outcomes pay the same.
Cross-Venue Arbitrage Detector
Arbitrage exists: prices sum to 0.950. Stake $484.21 on YES and $515.79 on NO to lock $52.63 (5.26%) whichever way it resolves.
Confirm both contracts resolve on identical terms, and remember venue fees plus the cost of moving capital between Polymarket (crypto) and Kalshi (USD) eat into the spread. Thin order books may not fill the full size.
Recession probability (yield curve)
The New York Fed's yield-curve model, translating the 10-year minus 3-month Treasury spread into a 12-month recession probability. Pre-filled with the latest yields.
Recession Probability Gauge
Curve is positive (+0.78pp). The model reads a 14.7% chance of recession within 12 months.
Based on the published Estrella-Mishkin probit model used by the New York Fed. It forecasts the next 12 months, not today, and the post-QE term premium can bias the read - treat it as one signal, not a verdict.
Fed rate-path simulator
Set how many 2026 cuts you expect and compare your implied year-end rate with the market.
Rate Path Simulator
Each cut = 25 bps (0.25%).
Build your own Signal
Re-weight the indicators behind the MacroOdds Signal and see how the cut-or-hold read changes.
Interactive Signal Weighting
Your weighting: is mixed
What it means for you
How a rate move hits a mortgage payment, and what inflation does to your savings.
Mortgage Payment Impact
Based on a 30-year fixed-rate term.
Inflation Real Return on Savings
You gained purchasing power this year.
See these in context on the Fed decision dashboard and the 2026 rate-cut path.