How we build the numbers

We show our working so you can check it, and we're honest about what a number can and can't tell you.

Calculators run in your browser

Every calculator on Financial Mastery runs on your own device. What you type is never sent to our servers or stored. The only exception is the optional “Pin on Pinterest” button, which uploads the result image you made for 24 hours so Pinterest can fetch it.

Formulas are standard, and shown

We use the formulas founders and investors use: net burn and runway month by month, LTV from ARPA, gross margin and churn, post-money SAFE conversion, ownership after a priced round including the option pool, the VC method of valuation, bottom-up market sizing and 1x non-participating liquidation preferences. Every calculator page lists its formulas and a worked example.

Sample companies

Worked examples use fictional sample companies from our workbooks: Loopdesk (SaaS), Tradelane (marketplace), Promptly AI (usage-based AI), Voltwise (hardware) and four more. Their numbers come from the SAMPLE files, recalculated with zero formula errors. They illustrate the mechanics; they are not benchmarks or forecasts.

Benchmark ranges

The green and amber ranges on our benchmark pages are the rules of thumb our Model Health Score uses for each business model. They reflect common early-stage practice and widely cited frameworks (for example, burn multiple bands popularised by David Sacks). They are not market data and they change with the market. Check current sources and talk to founders who raised recently.

What every result assumes

Constant rates. Growth, churn and cost growth are held steady unless a tool asks for a change.
Monthly or weekly steps. Cash tools work month by month; the 13-week check works week by week.
No taxes unless asked. Simple calculators ignore tax, working capital and debt unless they ask for them. The full workbooks include them.
Simplified cap tables. Dilution and SAFE tools treat each round simply. Real documents can contain terms that change the result.

How we test

Each calculator is checked against hand calculations and against the matching workbook. The workbooks themselves are recalculated end to end before every release, and every one must show zero formula errors.

Found a mistake?

Please tell us. We check and correct errors quickly and log meaningful fixes in the changelog.