Know the price you are paying.

A minimal amount of odds arithmetic tells you how much margin sits in a quote — the one number a disciplined staker should be able to read.

See live partner prices Start with a limit

Odds to probability

Decimal odds convert as 1 ÷ odds. A price of 2.00 implies 50%; 1.60 implies about 62.5%.

Sum the sides

A fair two-way market adds to 100%. Real quotes add to more, and the excess is the operator's margin.

Read margin as a fee

A 5% margin means roughly 5% of combined stakes is the built-in edge. It is the price of the market, not a hint about the result.

One line of arithmetic

For two-way decimal prices d₁ and d₂, margin = (1/d₁ + 1/d₂) − 1. Fractional odds like 3/1 equal 4.00 decimal. American odds: +150 → 2.50 decimal, −200 → 1.50 decimal.

No edge implied. Reading margin tells you what a wager costs. It does not tell you whether it wins. Most recreational staking outcomes are negative over time.

Why this belongs in a bankroll guide

Because it reframes the question. Instead of "will this win?", a disciplined reader asks "what am I paying, and is it inside the ceiling I already chose?" That is a question you can actually answer.