Tools & calculators

Small, transparent calculators that answer the questions reviews usually dodge. All math is shown on the page.

Find out whether a subscription tool pays for itself, and how many hours it has to save you each month to break even.

Project how a lump sum plus regular monthly contributions grows over time.

Work backwards from a target amount to the monthly contribution you need.

Convert between an hourly rate and a yearly salary using your real working hours.

Find the MRR, customer count, and months you need to cover your costs and stop losing money.

Estimate how much disk space a SQLite database will use from your row count, row size, and indexes.

Compare a flat-rate VPS with usage-based cloud pricing. Prices are illustrative sample data — maintain in data/ before launch.

Estimate the monthly cost of an API — per-call pricing plus LLM token pricing.

Turn a price and a customer count into MRR and ARR, or find the price you need for a target MRR.