This is the guide the rest of the blog hangs off. It covers what a bet is, how odds work, what the bookmaker takes, how the rules differ between Britain and the United States, and where to go next for each market.
What a bet actually is
A bookmaker offers a price on an outcome. That price implies a probability. You are betting that the real probability is higher than the one implied. Everything else — form, statistics, team news — is in service of that single judgement.
Three odds formats, one meaning
| Fractional (UK) | Decimal (Europe) | American | Return on 10 | Implied chance |
|---|---|---|---|---|
| 1/2 | 1.50 | -200 | 15 | 67% |
| 10/11 | 1.91 | -110 | 19.10 | 52% |
| Evens | 2.00 | +100 | 20 | 50% |
| 6/4 | 2.50 | +150 | 25 | 40% |
| 5/1 | 6.00 | +500 | 60 | 17% |
Decimal includes your stake, fractional shows only profit, and in American format a minus number is the stake needed to win 100 while a plus number is the profit on 100. Every licensed site lets you switch.
The overround: the one number that matters
Divide 100 by each decimal price in a market and add the results. A fair market totals 100. Anything above is the bookmaker's margin.
A football match at 1.85 / 3.60 / 4.20 totals 105.7, so the margin is 5.7 per cent. On a correct score board it might be 120. On a novelty market, 135. The number tells you what a bet costs before you have formed any opinion at all, and it varies more between markets than most bettors realise.
The markets, in order of usefulness
| Market | What it asks | Guide |
|---|---|---|
| Match result | Home, draw or away | 1X2 betting |
| Over/under | Above or below a line of goals or points | over/under |
| Both teams to score | Does each side score | BTTS |
| Double chance | Two of three outcomes | double chance |
| Total goals | Bands, exact totals, team totals | total goals |
| Goalscorer | Which player scores | anytime scorer |
| Correct score | The exact scoreline | correct score |
| Accumulators | Several selections in one bet | accumulators |
| Head-to-head | Which of two competitors finishes ahead | head-to-head |
| Ante-post | Long-range outright markets | ante-post |
| Cards and penalties | Discipline rather than goals | cards, penalties |
| Specials and novelty | Corners, props, non-sport | specials |
Britain and the United States are different markets
| Great Britain | United States | |
|---|---|---|
| Regulator | One: the Gambling Commission | One per state; no federal licence |
| Minimum age | 18 | 21 in most states |
| Where it is legal | Nationwide | Online in 30 states plus DC and Puerto Rico |
| Tax on winnings | None for the customer | Winnings are taxable income |
| Default odds format | Fractional | American |
| Betting exchanges | Established | Limited, a few states |
A licence covers the market it was issued for and no other: a UK-licensed bookmaker cannot take a bet from a customer in Ohio, and a Nevada-licensed book cannot take one from London. Full detail on UK bookmakers and US sports betting.
The four habits that decide results
- Take the best available price. A 5 per cent spread between books, captured on every bet, outweighs almost any handicapping edge.
- Stake level. Equal units, every time. Raising stakes to recover losses is how a bad weekend becomes a bad month.
- Bet fewer markets, better. The tight-margin staples reward attention. The specials board does not.
- Read the settlement rules. More bets are decided by a clause — extra time, own goals, substitutes, abandonments — than by a surprise result.
By sport
Football · tennis · basketball · NFL · ice hockey · Champions League · horse racing.
Betting responsibly
Every licensed operator must offer deposit limits, time-outs and self-exclusion, and must display links to support organisations. In Britain, GamStop blocks all licensed online operators in one registration and GamCare runs the National Gambling Helpline free of charge. Set a deposit limit when you open an account, before you have won or lost anything.
Frequently asked questions
Can betting be profitable?
For a small minority, over long periods, through price discipline rather than prediction. For nearly everyone else it is entertainment with a cost, and the cost is the overround.
Which market has the best odds?
The mainstream ones. Match result, over/under and Asian handicap carry the thinnest margins; correct score, method markets and novelty carry the widest.
Do I need more than one account?
If you bet regularly, yes. Two or three is enough to capture most of the price differences.
What is the most common beginner mistake?
Long accumulators. They feel like good value and they are where the margin compounds hardest.
Related guides: how to bet on football · compare bookmakers · betting bonuses · types of bet