In horse racing, SP stands for Starting Price.

It’s the official odds for a horse at the moment a race begins, based on the on-course bookmakers’ market.

Here’s how it works:

• Before a race, bookmakers and betting exchanges offer odds on each horse.
• Just before the race starts, those odds are collated, and the SP is set as a kind of industry standard.
• If you placed a bet “at SP,” you don’t know the exact odds when you strike the bet — you’ll be paid out at whatever the official SP is declared after the race goes off.

Example:

• You back a horse for £10 “to win at SP.”
• The horse’s SP is declared as 5/1.
• If the horse wins, you’ll be paid £50 winnings plus your £10 stake back.

Why it matters:

Many bookmakers now offer Best Odds Guaranteed (BOG): if you take an early price and the SP is bigger, you’ll be paid at the better odds.

SP is used for bets placed with bookmakers who don’t specify fixed odds.

It’s also the default for things like Tote returns or when people place bets without shopping around for best prices.