Unit size calculator

A unit is the stake you bet when you have an ordinary opinion. Enter the money you've set aside for betting and the share of it you want a unit to be, and this gives you the unit in dollars and what seven straight losers would cost.

Bankroll ($)Money set aside for betting onlyOne unit, as a percent of the bankrollOur bankroll guide suggests 1 to 2 percent

One unit: $10.00
Units in the bankroll: 100
Seven straight losers cost: $70.00 (7.0%)

What it shows

A $1,000 bankroll at 1 percent is a $10 unit, a hundred of them in the roll. Seven straight losers at $10 cost $70, 7 percent of the bankroll. Put the unit at 5 percent and the same run costs $350, more than a third of everything you set aside, and seven losers in a row happens to good bettors more often than they'd guess. The bankroll guide works out how often.

The mistake people make

Working the unit out once and never again. I'd redo it every month. The bankroll moves, and the unit should move with it: down after a bad month, so the same run doesn't take a bigger bite, and up only when the roll has actually grown. The other mistake is calling a bet "five units" because you feel strongly. I'd keep most bets at one unit and treat anything bigger as rare. A unit only means something if it stays the same size from one bet to the next. I'd rather be bored at 1 percent than exciting at 5.