Variance and Sports Betting

As much as punters would love to win consistently with their sports bets and suffer only the occasional loss, the reality is that there are fluctuations over time and a natural variance to the outcomes of their bets. Even the most successful bettors, who are used to claiming large payouts, tend to go through the odd spell where they simply can’t pick a winner.

A losing streak can damage your confidence and, most importantly, your budget, even if it does not last very long. Matters can then begin to spiral out of control and the only option left may be to stop and seek help but, with responsible gambling and bankroll management, you should be able to keep having fun with your sports betting and avoid any potential stresses. A key aspect of this is being aware of variance and taking it into account as you continue betting.

What is Variance?

Variance is a common statistical term which relates to the spread of numbers. There is a low variance for a set of numbers which are very similar and a high variance for numbers which diverge considerably from the expected amount. In sports betting, for example, a punter who liked to bet on even-money selections would expect to see a low variance where they win roughly half the time and lose the rest of the time.

Variance is particularly high when the sample size is small, i.e. at the start of a series of bets. When tossing a coin, for example, it would land on a head about 50% of the time if you tried it 1,000 times, but there is no guarantee that five of the first ten tosses would come up as heads. The punter who picks out selections at even-money odds may win eight out of their first ten bets, but over time this would likely even itself out (and probably fall under 50% because the odds have been set in the favour of the bookmaker).

The Impact of Variance

There is variance in poker, casino games or even on the stock markets, and those who love sports betting have to be willing to accept a high level of risk and manage their bankroll accordingly, otherwise they may be in for a nasty surprise. Regardless of how skilled a bettor is at picking out wagers with the best value and how regularly they win, they will suffer the occasional loss and if they are not careful they could have all the money in their account wiped out.


  • Fred has built his sportsbook account up to £200 as a result of some astute football bets. He then picks out five wagers ahead of Saturday’s games at close to even-money odds and decides to put £10 on each one. He wins three out of the five to boost his balance to £210 (3 x £20 - 5 x £10).
  • The following Saturday, Fred again picks out five even-money bets and puts £10 down on each one. This time, Fred does even better and wins four out of the five (4 x £20 - £5 x 10) to boost his balance to £240.
  • Fred decides the following week that as he is doing so well, he will increase his stake on each bet to £25. This time, however, he wins only one of the five bets ((1 x £50 - 5 x £25) and his balance goes down to £165.
  • The next week, Fred is determined to win back his money and splits the whole of his £165 across five bets. He loses them all and is left with no money in his account, despite being a skilled punter who had built up £200 and then won with seven of his first ten bets of the month.

The danger of underestimating or ignoring variance is that bettors who are doing well may start to think they can keep pushing the limits, and eventually there will be a bad week or two which can ruin all their good work.

Sports bettors must therefore anticipate that there will be lows as well as highs, and manage their bankroll in such a way that they continue to wager only what they can afford to lose and take into account any possible negative variance. The general advice is to not make bets that will be equal to, or more than, a very small percentage of your bankroll, which gives you enough left in your funds for gambling that you can carry yourself through losing streaks.

Quick Tips for Dealing with Variance

  • Set out a budget which can cope with losing streaks.
  • Have a maximum bet, perhaps ten percent of your bankroll.
  • Only bet with money you can afford to lose.