How to convert American odds to decimal and implied probability
American odds show how much you win on $100 (+150) or how much you risk to win $100 (-150). Decimal odds show your total return per $1 staked. Implied probability converts either into the win rate the price assumes.
Why implied probability is the number that matters
The conversion that changes how you bet is the last one. -110 implies 52.4%. That means a coin-flip market priced at -110 on both sides needs you to be right more than 52.4% of the time before you make a cent. Every price is a probability wearing a costume.
Every tool downstream of this one — EV, Kelly, hold — starts from this conversion. Read a price as a probability at a glance and you are already ahead of most of the betting public.
