Tools you can use.
Practical calculators and reference materials from Investing With Purpose, built to put the IWP Concepts to work. Everything here is free, with no sign-up.
Downloadable resources
Templates and cheat sheets to drop straight into your own process.
100 finance formulas across 11 sections, from time value of money to options, each with a plain-English note and a difficulty level. A clean, connected reference to keep.
A practical field guide to delta, gamma, theta, vega, and rho: what each measures, how it behaves, and how to trade around it, with sign tables and a tear-out cheat sheet.
A professional discounted cash flow model: fair-value range, mid-year convention, a WACC vs growth sensitivity table, and a Conservative / Base / Optimistic scenario toggle.
A linked three-statement model with three years of history, working-capital drivers derived from that history, an opex-growth driver, and a Conservative / Base / Optimistic scenario toggle.
Interactive tools
Portfolio Builder
Mix your assets and see what the blend returns, and how risky it is, over the long run. Set an allocation across stocks, bonds, direct real estate, gold, cash and alternatives, in dollars or percentages, with the rest auto-balancing to 100%, adjust each one's expected return, and the tool works out your blended return, your portfolio risk after diversification, and how the whole thing could grow. It shows why the split between assets, not any single pick, drives most of your long-term result.
Set any class by dollars or the slider, the rest rebalance so you always stay at 100%.
Diversification trims your risk from 11.6% (the average of the parts) to 9.3% (the portfolio), because the assets don't all move together.
How it works
The effective return is the weighted average of each asset's return by its share of the portfolio (weights are normalised to 100%). Portfolio risk is the annualised volatility from the full covariance of the holdings, so low-correlation assets lower it below the simple average. For a mortgaged property the return and risk are measured on your equity: leverage of loan-to-value multiplies the gap between your yield and your mortgage rate, in both directions. Long-run averages, not guarantees. Educational only.
Position Size Calculator
Work out how many shares to buy so a losing trade costs only what you decided to risk. Set your risk as a share of your whole account (the 1% rule), choose how much room to give the trade, and it sizes the position and places your stop. Because risk is measured against your account, ten trades at 1% each put about 10% at risk at most, never your whole portfolio.
Sized to risk $496.00 (0.99% of your account). Buy 62 shares with your stop 8% below entry, at $92.00.
Formula used
shares = (account × risk%) ÷ (entry × stop%) · capped at (account × maxPos%) ÷ entry
Your risk budget (account × risk%) divided by the per-share loss at your stop gives the share count, so a stop-out costs exactly your budget. The position is then capped at your chosen share of the portfolio. Stop price = entry × (1 − stop%). Shares are rounded down.
Compound Interest Calculator
Project how an investment grows when returns compound and you keep contributing. Compounding is the engine behind long-run wealth: each period's gains earn their own gains, so time in the market matters more than timing it.
Formula used
A = P(1 + r/n)nt + PMT × [((1 + r/n)nt − 1) ÷ (r/n)]
P = initial, PMT = contribution per period, r = annual return, n = periods per year, t = years.
FIRE Calculator
Financial independence is the point where your investments can cover your spending for good. Set what you have, what you save, and what you'll spend, and see the age you could reach it. By default it uses the classic 4% rule: your nest egg is 25 times your yearly spending. Open Fine-tune to change the return, the withdrawal rate, or switch to a drawdown that runs your money down to a chosen age.
You save $30,000 a year (35% of income).
That's about 23 years away, with a $1.4M nest egg that covers $55,000 a year.
How it works
Each year your savings grow by your real return and you add what you don't spend (income minus spending). The tool finds the earliest age your balance reaches your FIRE number. By the 4% rule that number is 25 times your yearly spending, a pot large enough that returns cover your withdrawals for good. Switch to spend to an ageand it instead sizes the pot to run down to about zero by the age you pick. Returns are real (after inflation), so every figure stays in today's money. Educational only, not a retirement plan.
Options Payoff Calculator
Pick a strategy or build your own, then see the profit-and-loss at expiration across every underlying price. Green is profit, red is loss; the dashed line marks today's price and the dots mark break-even.
Profit / loss at expiration ($) vs the underlying price. Hover for any price. Each contract = 100 shares.
How it works
At expiration a call is worth max(price − strike, 0) and a put max(strike − price, 0). Buying pays the premium; selling collects it. The curve sums every leg across underlying prices, so max profit, max loss, and break-even fall out of the shape. This ignores early exercise, dividends, and time value before expiry. Educational only.
Where the reference becomes action.
The Investing With Purpose Substack applies this same research standard to individual stocks: fundamental and technical analysis, the news that moves them, and a clear, risk-managed trade plan for each, with a fresh plan across every name we cover each week.