Free tools

Calculators

Small, exact tools for the questions I kept answering by hand. No signup, no accounts, and nothing leaves your browser.

Derivatives
Options P&L calculator
Build any combination of options, futures and underlying, and see the exact payoff at expiry, modelled P&L before it, Greeks and breakevens.Open
Derivatives
Dynamic hedging simulator
Sell an option and delta-hedge it to expiry. Set the volatility you sold against the volatility the market delivers, and watch the premium leave through the hedge.Open
Derivatives
Volatility smile
Put in a strip of bid-ask quotes and get an implied vol for each side, a fitted smile, and the strikes the market prices clear of its own curve.Open
Personal finance
How much is enough?
Retirement planning across an ISA, a LISA and a pension. A thousand return paths give the chance the money lasts, and the spending it could actually support.Open
Personal finance
UK take-home, four ways
Employed, self-employed, own company or umbrella — the same money through each wrapper, so you can see what the structure costs rather than the band.Open
Personal finance
Compensation comparison
Startup, hypergrowth or enterprise: price each bet as a distribution — downside, weighted and upside — after dilution and UK tax.Open