Who built this

ProbLab is run by a small, named team: a working statistician (the math side), an educator (the "explain it like I'm 15" side), and a tabletop game designer (the "make it actually fun to use" side). We maintain the site part-time and publish under our real names on the contact page.

Why we built it

Most "probability calculator" sites we found in 2024–2026 do one of three things:

They give you a single number with no context — so you don't know whether to trust it or act on it.
They show a generic ad-laden interface that buries the formula and copies textbook examples verbatim.
They try to sell you a "winning system" by abusing math.

None of those match what an actual person with an actual question (a teacher prepping a class, a poker player checking gut feel, a PM sizing an A/B test) actually needs. ProbLab is the calculator we wanted ourselves.

Who it's for

Educators and students. Visualizations make formulas stick. Each tool has a "what this means" section written for a curious 16-year-old, not a math PhD.
Gamers. D&D players running exploding dice, poker players computing hand equity, board-gamers checking ruin probabilities. We include game-specific presets (5e advantage, World of Darkness dice pools, etc.).
Analysts and product managers. Confidence intervals, A/B sample sizing, chi-square independence, Bayesian updates with prior/posterior — the standard inference toolbox without paying for a stats SaaS.
Curious adults. "What does it mean that the test is 95% confident?" — every result page tries to answer the question behind the calculation.

What we intentionally don't do

We don't sell betting picks or claim any tool "predicts" future outcomes. Probability calculators describe models; they do not predict.
We don't collect personal data. There's no login, no email capture, no behavioral tracking beyond what Google AdSense itself does. See Privacy Policy.
We don't show ads that look like buttons, "Download" prompts, or fake system notifications. See Disclaimer for the full standard.
We don't promise "secret" math. Every formula is shown or linked in the tool's explanation section.

How we handle corrections

If you find a math error, a broken link, or an unclear explanation, we fix reported issues within seven days. Each tool page has a "Report an error" mailto at the bottom. We document fixes in the changelog below.

Changelog

2026-09-16 — Initial public release of 22 calculators, About / Privacy / Disclaimer pages.
2026-09-02 — Internal review pass. Removed a non-essential third-party script that was inflating load time.

Contact

General questions, corrections, partnership ideas: hello [at] problab.example. (Replace the obvious placeholder with a real address before going to production.)

Frequently asked questions

How do I use About ProbLab step by step without mistakes?

Follow the order given in the usage section: ProbLab is built by a small team of statisticians, gamers, and educators. Learn who it's for, what it intentionally does NOT do, and how we handle corrections. The step-by-step part matters less than the unit check that sits inside it. Confirm every unit matches the thing you are actually trying to measure before you press calculate - that single check catches more wrong answers than any other habit, and it costs about ten seconds.

What are the common mistakes when using About ProbLab?

Most common mistakes come down to four habits: entering 20 when the field expects 0.2 because the field is a percentage; leaving a field blank and accepting the default without checking what it stands for; changing one input and reading a result that was calculated before the change; and quoting the output as an exact figure when the page describes it as a reference estimate. Press calculate again after any edit, and treat the number as a reference point rather than a final answer.

Where does About ProbLab stop being useful?

ProbLab is built by a small team of statisticians, gamers, and educators. Learn who it's for, what it intentionally does NOT do, and how we handle corrections. Put another way, this page answers one narrow question: given the numbers you typed, what does a quick estimate look like. It is not for looking up authoritative data, checking official documents, reviewing a contract line by line, or making a professional judgement call. If a decision depends on money, a signature, or a commitment to somebody else, go back to the source material and confirm the numbers there first.

How do I read the result from About ProbLab?

Read the final figure first, then come back to this section for the conditions behind it: ProbLab is built by a small team of statisticians, gamers, and educators. Learn who it's for, what it intentionally does NOT do, and how we handle corrections. Keep two things apart: the number itself, which comes from the values you typed, and the assumptions it depends on, which decide whether that number is meaningful. The page sets out what a higher or lower result means for your case, so check that direction as well as the magnitude.