About Teacher's Bet

By · author of the MIT-licensed teachersbettextbook library ·

Teacher's Bet is a sports-betting analytics calculator at teachersbet.com. It computes fair prices, expected value, Kelly stake sizes, arbitrage and Kalshi fees, and shows the full derivation for every number. It is not a sportsbook and does not accept wagers, hold funds, or place bets.

What does Teacher's Bet do?

It turns a posted price into a number you can check. Paste a two-sided moneyline and it strips out the book’s margin to leave a fair probability. Compare that probability to the price you were offered and it prints the expected value. Feed it a bankroll and it returns the Kelly stake. Give it two books and it finds the arbitrage split. Give it a Kalshi contract and it prices the fee before the trade and again on the way out.

Each of those is a page you can open right now, free:

Every result opens into the arithmetic that produced it: which de-vig method ran, the intermediate values, and the timestamp on each input. That is the whole product. The claim is not “trust us” — it is check us.

What does Teacher's Bet not do?

It does not take wagers, hold money, or place a bet for anyone. It is a calculator, not a book and not a broker.

It does not sell picks and it does not give betting advice. No page on this site says “bet this.” Outputs are arithmetic on inputs you supplied or on posted market prices, framed as arithmetic. What you do with a number is your decision and your risk.

It does not guarantee an outcome, because nothing can. When the inputs contain no edge, the answer printed is $0 — never rounded up into something that looks actionable. And there are no testimonials, no star ratings and no user counts anywhere on the site, because none of them would be real. No sportsbook pays for placement here.

Who runs Teacher's Bet?

Alex Thornton, in Syracuse, New York. One person: writes the pages, writes the math, reviews the numbers, ships the deploys. There is no staff, no editorial board, and no anonymous “team of experts.”

Every article carries a byline and a last-reviewed date, and the date is the one in the page’s own structured data — the two cannot drift apart. Corrections go to alex@teachersbet.com; the standing policy is on the contact page.

Is Teacher's Bet free?

The math is free and stays free. Every calculator on the site, the whole Learn course, and the formula sheet are free permanently — no account, no email, no card. The free tier is not a trial that expires.

The paid tier is priced but checkout is not open yet, and the live exchange feed it depends on is still being built. What it will buy is speed on live market data and depth of stored history. It will not buy access to a formula, and it will not buy picks. Pricing is on one page, with the renewal terms and the cancel path stated in plain language.

Where does the math come from?

It is published, not proprietary. The moneyline conversions, the three de-vig methods, Kelly sizing and the arbitrage split are implemented in teachersbettextbook, an MIT-licensed Python library on PyPI. Install it and reproduce every calculator number on the site without asking anyone’s permission — that is the point of publishing it. The pooled fair line is the exception: the consensus code is not in the package, though its weighting formula and constants are printed on the methodology page.

The formula sheet lists every formula the site uses with each symbol named and its units given. The methodology page explains how several venues’ prices are pooled into one fair line, prints the exact weighting formula and its constants, and states plainly which parts of the pipeline run today and which do not. Open source covers the library itself.

One thing is deliberately not published, once it exists: the fitted per-venue calibration weights and the correlation structure behind the pooled fair line. Neither is computed yet, and the cold-start weighting running in their place is printed in full — formula, constants and the venue tier table — on the methodology page. The result is always shown: the fair price, how many venues qualified, how much they disagreed.

Where do the odds come from?

First-party licensed APIs only: the Kalshi exchange API for prediction-market prices, and a commercial odds API for sportsbook lines. Nothing here is scraped and no resold feed is purchased. Every quote carries two timestamps — when it was pulled, and when the venue last moved it — and a stale price is labelled stale rather than dressed up as current.

Is this the Boy Meets World episode?

No. Teacher’s Bet is a sports-betting analytics tool. It is not the 1993 Boy Meets World episode of the same name, nor the novel by Ruby Steele.

The name is possessive — the teacher’s bet, not a site for teachers. A teacher works the problem on the board where everyone can see each step, which is the only feature this site really has.

The standing rules

  • Never emit “bet this.” Every output is a calculation, framed as a calculation.
  • Every number carries a timestamp: when it was computed, and when the venue last moved the price.
  • Every result has a working “show the work” path. If a calculation can’t be derived step by step, it doesn’t ship.
  • The honest zero: no edge in, $0 out.
  • Refuse to print unsupported numbers. Every fair line ships with the number of venues behind it and an agreement label, and the confidence read is cut rather than the number being dressed up as certain. This one is not fully built. A market quoted by a single venue is still published today, with its venue count shown as 1; a hard refuse-to-publish gate below two qualifying venues is the next change to the consensus path. The methodology page tracks exactly what runs.

These are product invariants, not marketing — which is why the one that is only partly implemented is labelled as such rather than quietly claimed. They are also why the editorial policy and the responsible gambling page exist.

Frequently asked questions

What is Teacher’s Bet?

Teacher’s Bet is a sports-betting analytics calculator at teachersbet.com. It computes fair prices, expected value, Kelly stake sizes, arbitrage and Kalshi fees, and shows the full derivation for every number. It is not a sportsbook and does not accept wagers, hold funds, or place bets.

What does Teacher’s Bet not do?

It does not take wagers, hold money, or place a bet for anyone. It does not sell picks or issue betting advice, and it never prints an instruction to bet. It does not guarantee an outcome: when the inputs contain no edge, the answer printed is $0. It carries no testimonials, no ratings and no user counts, and no sportsbook pays for placement on the site.

Who runs Teacher’s Bet?

Alex Thornton, in Syracuse, New York. One person writes the pages, writes the math, reviews the numbers and ships the deploys. There is no staff and no editorial board. The contact address is alex@teachersbet.com and it reaches him directly.

Is Teacher’s Bet free?

The math is free and stays free. Every calculator and the whole Learn course are free permanently, with no account, no email and no card, and the free tier is not a trial. The paid tier is priced but checkout is not open yet; when it opens it will buy speed on live market data and depth of stored history, never access to the formulas.

Where does the math come from?

The formulas are published, not proprietary. The odds conversions, the three de-vig methods, Kelly sizing, the arbitrage split and the Kalshi fee schedule are implemented in teachersbettextbook, an MIT-licensed Python library on PyPI, so anyone can reproduce those numbers without asking. The pooled fair line is the exception: its consensus code is not in the package, though its weighting formula, constants and venue tier table are printed on the methodology page.

Is Teacher’s Bet the Boy Meets World episode?

No. Teacher’s Bet is a sports-betting analytics tool. It is not the 1993 Boy Meets World episode of the same name, nor the novel by Ruby Steele.