A-F: ATS, Bankroll, CLV, Decimal Odds, Edge, Futures
ATS (Against the Spread). A team’s record when measured against the point spread rather than outright wins and losses. If the Celtics are -6.5 favourites and win by 8, they covered the spread and are 1-0 ATS. If they win by 5, they failed to cover and are 0-1 ATS. ATS records are the primary performance metric for spread bettors. A team with a strong win-loss record but poor ATS record is overvalued by the market.
Bankroll. The total amount of capital dedicated to betting, kept separate from personal finances. A bankroll of £5,000 at £50 per unit provides 100 units of risk capacity. The bankroll is not what you can afford to lose — it is the capital base from which your system operates. Professional bettors treat it as a business account, never mixing it with household money.
CLV (Closing Line Value). The difference between the odds you received when placing your bet and the closing odds at tip-off. If you bet the Nuggets at 1.95 and the line closes at 1.88, you captured positive CLV — you got a better price than the market’s final assessment. Consistently positive CLV over hundreds of bets is the strongest indicator of long-term profitability, more reliable than win rate alone.
Decimal Odds. The standard odds format for UK bettors. Decimal odds represent the total return per £1 wagered, including the original stake. Odds of 1.91 mean a £100 bet returns £191 (£91 profit plus £100 stake). To calculate implied probability: divide 1 by the decimal odds. So 1.91 implies a 52.36% probability. UK bookmakers default to decimal or fractional; American odds (-110, +150) require conversion.
Edge. The bettor’s advantage over the bookmaker’s price, expressed as a percentage. If your model gives a team a 55% chance of covering the spread and the bookmaker’s implied probability is 52%, your edge is approximately 3%. Positive edge means the bet has positive expected value. Negative edge means the bookmaker has the advantage. Professional bettors only bet when they identify a quantifiable edge.
Futures. Bets on events that will be decided at a later date — NBA championship winner, MVP, season win totals. Futures lock up capital for extended periods (months, in the case of championship bets) and carry higher bookmaker margins (15-25% overround) than individual game markets. The trade-off is higher potential payouts and the opportunity to bet on opinions the market has not yet fully formed.
G-O: Handle, Implied Probability, Juice, Kelly, Line, Moneyline, Overround
Handle. The total amount of money wagered on a market or event. In-play betting now constitutes 62.35% of the total online betting handle, a proportion that continues to grow. Handle is a market-level metric: it tells you how much action a game or market is attracting, which in turn indicates how efficiently priced that market is likely to be. High-handle markets (prime-time NBA spreads) are sharper; low-handle markets (Tuesday night player props) are softer.
Implied Probability. The probability of an outcome as implied by the bookmaker’s odds. Calculated as 1 divided by the decimal odds. Odds of 2.00 imply a 50% probability; odds of 1.50 imply 66.7%. The sum of implied probabilities for all outcomes in a market will exceed 100% — the excess is the overround, the bookmaker’s built-in margin.
Juice. Another term for vig — the commission the bookmaker charges on each bet. At standard NBA spread pricing, the juice is built into odds of 1.91 on both sides: the true fair odds would be 2.00 (a coin flip at 50/50), but the bookmaker charges 1.91, extracting approximately 4.5% margin. Juice is the cost of doing business in sports betting.
Kelly Criterion. A staking formula that calculates the optimal bet size based on your edge and the odds offered. The formula is: (Edge / (Decimal Odds – 1)). If your edge is 3% and the odds are 1.91, the Kelly stake is 3.3% of your bankroll. Most professional bettors use fractional Kelly (typically quarter or half Kelly) to reduce variance at the cost of slower bankroll growth.
Line. The bookmaker’s published odds or point spread for a game. “The line is -4.5” means the favoured team is expected to win by 4.5 points. Lines move in response to betting volume, injury news, and sharp-money action. The opening line is the first line published; the closing line is the final line at tip-off.
Moneyline. A bet on which team will win outright, without a point spread. Moneyline odds reflect the probability of each team winning. A moneyline of 1.40 for the favourite implies a 71.4% win probability; 3.20 for the underdog implies 31.3%. Moneyline bets are most useful when you believe a team will win but are uncertain about the margin.
Overround. The bookmaker’s total margin across all outcomes in a market. Calculated by summing the implied probabilities of all outcomes. A two-outcome market with odds of 1.91 on both sides has an overround of approximately 104.7% (52.36% + 52.36%). The 4.7% excess is the bookmaker’s profit margin. Lower overround means better value for bettors; the odds conversion guide explains how to calculate and compare overround across operators.
P-Z: Parlay, Props, ROI, Spread, Totals, Unit, Vig, Wager
Parlay (Accumulator). A single bet combining two or more selections, all of which must win for the bet to pay out. Parlays offer higher payouts but compound the bookmaker’s margin with each leg added. A two-leg parlay at 1.91 per leg pays 3.65 (1.91 x 1.91), but the true fair payout at 50/50 odds would be 4.00 (2.00 x 2.00). The margin grows exponentially with each additional leg.
Props (Proposition Bets). Bets on specific events within a game rather than the overall outcome. NBA player props include points scored, rebounds, assists, three-pointers made, and combined stat markets. Props are generally priced less efficiently than spreads because they attract less sharp volume and require more complex modelling inputs.
ROI (Return on Investment). Profit divided by total amount wagered, expressed as a percentage. A bettor who wagers £10,000 across a season and profits £500 has a 5% ROI. Professional NBA bettors target 4-10% ROI. ROI is the most honest performance metric because it accounts for both win rate and average odds, unlike win rate alone.
Spread (Point Spread / Handicap). A points-based handicap applied to equalise the expected outcome of a game. If the Bucks are -5.5 favourites, they must win by 6 or more for a spread bet on them to cash. The opponent at +5.5 can lose by up to 5 and still cover. Spread betting is the most popular NBA market and the most efficiently priced.
Totals (Over/Under). A bet on whether the combined score of both teams will exceed or fall short of a number set by the bookmaker. A total of 224.5 means you bet on whether the final combined score will be 225 or higher (over) or 224 or lower (under). Totals are driven primarily by pace and efficiency data.
Unit. A standardised bet size, typically representing 1% of your bankroll. A bettor with a £5,000 bankroll and a one-unit standard bet wagers £50 per play. Tracking bets in units rather than pounds normalises your performance data and makes it comparable across different bankroll sizes and stake levels.
Vig (Vigorish). The bookmaker’s commission on each bet, functionally identical to juice. At -110 pricing (1.91 decimal), the vig requires a bettor to win 52.4% of bets to break even. The vig is the primary structural obstacle to profitability in sports betting — every bet you place starts at a slight disadvantage, and only a genuine edge can overcome it.
Wager. Any individual bet placed with a bookmaker. A wager consists of a selection (the outcome you are betting on), a stake (the amount risked), and odds (the price at which the bet is placed). In systematic betting, every wager should be documented in a tracking spreadsheet with full details including CLV and reasoning.
