Odds Formats

Prediction market share prices directly represent implied probabilities. A YES share priced at $0.70 implies a 70% probability of the event occurring. This page explains how to interpret prices and convert between common odds formats.

Price as Probability

The simplest way to think about prediction market prices:

Share Price	Implied Probability
$0.05	5%
$0.20	20%
$0.50	50%
$0.80	80%
$0.95	95%

If you think the true probability is higher than the price implies, buying is a positive expected value bet. If you think it’s lower, the other side offers value.

Converting Between Formats

To Decimal Odds
To American Odds
To Fractional Odds

Decimal odds show your total return per $1 wagered (including your stake).Formula: Decimal Odds = 1 / Price

Price	Decimal Odds	Meaning
$0.20	5.00	Win 5x your stake
$0.50	2.00	Win 2x your stake
$0.80	1.25	Win 1.25x your stake

Example: Buy at $0.25, decimal odds = 4.00. A $10 bet returns $40 if you win ($30 profit + $10 stake).

American odds show profit relative to $100 wagered.For prices below $0.50 (underdog): American Odds = (100 / Price) - 100, shown as positiveFor prices above $0.50 (favorite): American Odds = Price / (1 - Price) × 100, shown as negative

Price	American Odds
$0.20	+400
$0.33	+200
$0.50	+100 / -100
$0.67	-200
$0.80	-400

Price	Fractional Odds
$0.20	4/1
$0.25	3/1
$0.50	1/1 (evens)
$0.75	1/3
$0.80	1/4

Quick Reference Table

Probability	Price	Decimal	American	Fractional
10%	$0.10	10.00	+900	9/1
20%	$0.20	5.00	+400	4/1
25%	$0.25	4.00	+300	3/1
33%	$0.33	3.00	+200	2/1
50%	$0.50	2.00	+100	1/1
67%	$0.67	1.50	-200	1/2
75%	$0.75	1.33	-300	1/3
80%	$0.80	1.25	-400	1/4
90%	$0.90	1.11	-900	1/9

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Price as Probability

Converting Between Formats

Quick Reference Table

​Price as Probability

​Converting Between Formats

​Quick Reference Table

Price as Probability

Converting Between Formats

Quick Reference Table