The calculators behind the maths
Six free tools for sizing bets and reading prices: each on its own page, mobile-first, and updating as you type. Everything runs in your browser and nothing is stored.
Arbitrage
Split a stake across two books to lock a margin while prices hold.
OpenExpected Value (EV)
See whether a price is worth more than it costs over volume.
OpenKelly Staking
Size a stake from your edge and bankroll.
OpenNo-Vig Fair Odds
Strip the book's margin to reveal the fair price.
OpenOdds Converter
Convert decimal, American, fractional and implied odds.
OpenVig & Hold
Measure the margin baked into a market.
OpenWhat the numbers mean
- Arbitrage
What is arbitrage betting?
Arbitrage means backing every outcome of an event across different books at prices that, together, cover the whole market for less than it pays out. When the numbers line up, the position carries a margin while those prices hold; it depends on the odds not moving and on staking each side correctly, so it is a market inefficiency, not a payout promise.
Read - +EV
What is +EV betting?
A bet is positive expected value when the price on offer implies worse odds than the real chance of the outcome. Over many bets of that kind the maths leans in your favour, even though any single bet can lose. The edge is statistical and shows up across volume, never in a guarantee about one result.
Read - Australia
Is arbitrage legal in Australia?
Arbitrage betting is legal for Australian punters; you are simply placing ordinary bets at licensed bookmakers. Bookmakers don't like it, though: they may limit your stakes or close your account if they spot the pattern.
Read - The basics
What is implied probability in betting?
Every price is a probability wearing different clothes. Implied probability is the translation, and it is the first calculation worth learning because almost everything else in price led betting is built on top of it.
Read - The basics
What is devigging?
Devigging means taking the bookmaker's margin back out of a price to see what the market actually thinks. It is the step between reading a price and having a probability estimate worth betting against.
Read - The basics
What is closing line value (CLV)?
Closing line value compares the price you took against the price the market settled on just before the event started. It is the closest thing price led betting has to an early answer, because results take far longer to say anything than most people expect.
Read - The basics
What is the Kelly criterion?
The Kelly criterion answers a question most bettors never ask properly: given an edge, how much should you actually stake? It is a formula about survival as much as growth, and the reason most people who use it seriously use less of it than it recommends.
Read - The basics
How do bookmakers set odds?
A price is not a prediction handed down from somewhere. It is a number a business publishes, adjusts and defends, and understanding how it gets set is the difference between guessing where value might be and knowing where to look.
Read - The basics
What is line shopping?
Line shopping is the least glamorous idea in betting and the one with the largest effect on expected value. It requires no model, no prediction and no edge of your own: only accounts, and the discipline to check.
Read - The basics
Bankroll management for bettors
Bankroll management is the part of betting that decides whether a method survives long enough to be tested. It is not about what you might make. It is about not being knocked out of the game by an ordinary run of bad luck.
Read - The basics
Arbitrage betting vs matched betting
The two are often described as the same thing because they look identical from the outside: several accounts, every outcome covered, a calculator open. What separates them is where the edge comes from, and that difference changes everything downstream.
Read
The longer reads
Arbitrage betting in Australia
Arbitrage betting means covering every outcome of an event across different bookmakers, at prices that together cost less than the market pays out. It is legal in Australia and it is not complicated to understand. What decides whether it works for you is not the maths, it is everything around the maths.
ReadPositive EV betting in Australia
A positive expected value bet is one where the price on offer implies a worse chance than you believe the outcome actually has. You will lose plenty of them. The argument is that across enough of them, the pricing gap shows up in the results.
ReadBetting software in Australia
Betting software watches bookmakers' prices and tells you when something is out of line. That is the entire job. Understanding how narrow that job is will save you more money than any feature comparison.
ReadWhy Australian bookmakers limit accounts
Getting limited is the most common reason people stop betting seriously, and almost nobody warns you about it beforehand. It is not a punishment and it is not personal. It is a commercial decision a bookmaker is entitled to make, and it will eventually be made about most consistent winners.
ReadThe bookmakers we scan
The eight Australian books the software watches, how each prices its markets, and how each treats winning accounts.
ReadFor education only, not financial advice. 18+. Gamble responsibly. Past performance does not guarantee future results.