Ask most tradespeople and freelancers how they landed on their price, and the honest answer is usually "what felt about right" or "what the last person charged." That's not a confidence problem, it's a maths problem — and it's the single biggest reason busy people still aren't making the money the work should generate.
Fuel, insurance, tools wearing out, software subscriptions, the van — none of that shows up on a single invoice, so it's easy to under-account for across the year. A price that only covers the job in front of you, with nothing left over for the things keeping the business running, isn't really profit. It's turnover with a delay on the bad news.
This is where a proper calculator earns its keep over a rough mental estimate. Tools like CalculatorAI let you work out a real rate from your actual expenses and hours rather than a guess, and keep a running expense tracker so the number stays accurate as costs change — not just a one-off calculation you do once and never revisit.