README

A small Yii 2 widget that removes the bookmaker margin (the "vig" or "overround") from betting odds, so visitors can see the fair odds and the true chance behind any price.

2-way markets (tennis, basketball, head-to-head) or 3-way markets (home / draw / away)
Decimal (2.50) or American (+150 / -110) odds
Shows the fair chance, fair odds and the bookmaker margin as the visitor types
Runs in the browser: no API key, no external requests, no cookies
Labels can be overridden for translation

Installation

composer require betbetter/yii2-novig

Usage

use betbetter\novig\NoVigWidget;

echo NoVigWidget::widget();                        // 2-way, decimal odds

echo NoVigWidget::widget([
    'outcomes' => 3,                               // home / draw / away
    'format' => 'american',                        // +150 / -110
]);

Options

Option	Values	Default
`outcomes`	`2` or `3`	`2`
`format`	`'decimal'` or `'american'`	`'decimal'`
`showCredit`	show a small "how the margin is removed" link	`false`
`options`	HTML attributes for the container	`[]`
`labels`	override any label, e.g. `['home' => 'Local']`	English

How it works

Each price is turned into an implied probability (1 / decimal odds). The probabilities are added up; anything above 100% is the bookmaker margin. Each probability is divided by the total so they add up to 100% again (the proportional method), giving the fair chance and the fair odds.

Example: 1.91 / 1.91 adds up to 104.7%, so the margin is 4.7% and the fair odds are 2.00 / 2.00.

For reference, across 69.6 million pre-match markets (July to September 2026) the average margin was about 4.8% on two-way match bets and 7.6% on player props: State of the Vig 2026 (open data, CC BY 4.0). A browser version is at betbetter.world/tools/no-vig-calculator.

Licence

MIT. Made by Bet Better.

betbetter / yii2-novig

Package info

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