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Betting Maths Glossary: Odds, Edge and Probability Terms Explained
Quick answer: This glossary explains the 45 maths and odds terms that decide whether a bet is worth making, from house edge and RTP to expected value, closing line value and the Kelly criterion. Each definition is short, most include a worked peso example, and each links to the Maya88 guide that covers it in full.
Every number on this page is our own worked example, using standard published figures for each game. Real games and bookmakers vary, so always check the rules, pay table and odds of the exact game you play.
A
- Accumulator (parlay)
- One bet that combines several selections; every leg must win. The bookmaker's margin compounds with each leg: three legs at 1.91 pay 6.97 in total, against fair odds of 8.00 if each were a true 50/50, so you get about 13% less than a fair price. Read the full guide →
- Asian handicap
- A handicap that removes the draw by giving one side a goal head start, sometimes in quarter steps. A quarter line such as -0.75 splits your stake across the two nearest half-goal lines, so a result can settle as half-won or half-lost. Read the full guide →
B
- Banker bet
- The baccarat bet on the Banker hand. After the usual 5% commission on wins, its house edge is about 1.06%, slightly lower than the Player bet's 1.24%. Read the full guide →
- Bankroll
- The money you have set aside for betting and nothing else. Treating it as a separate, fixed pot is what makes sensible stake sizing possible. Read the full guide →
- Betting unit
- A fixed stake size, usually 1% to 2% of your bankroll, used for every bet. With a ₱10,000 bankroll, one unit at 1% is ₱100. Read the full guide →
- Bonus buy
- A slot option that lets you pay a set price, often around 100 times your bet, to go straight to the bonus round. It changes how quickly you see results, not the fact that the game keeps an edge over time. Read the full guide →
- Break-even rate
- The share of bets you must win just to break even at a given price. At odds of 1.91 it is 1 ÷ 1.91, or about 52.4%, which is why winning 52% of even-money bets still loses money. Read the full guide →
C
- Card counting
- Tracking which cards have been dealt to estimate whether the remaining shoe favours the player. It does not help in RNG blackjack, where the deck is reshuffled for every hand. Read the full guide →
- Cashback
- A refund of part of your net losses over a period. 10% cashback on a ₱5,000 net loss returns ₱500, so it softens losses but does not turn a losing game into a winning one. Read the full guide →
- Closing line value (CLV)
- How the price you took compares with the final price before the event starts. Taking 2.20 on a selection that closes at 2.00 means you beat the closing line by 10% on price, a good sign your bets have value. Read the full guide →
D
- Decimal odds
- Odds shown as the total return per ₱1 staked, including the stake. A ₱100 bet at 2.50 returns ₱250 if it wins, which is ₱150 profit. Read the full guide →
- Double zero
- The extra 00 pocket on an American roulette wheel. It raises the house edge from 2.70% on a single-zero wheel to 5.26%. Read the full guide →
E
- Expected value (EV)
- The average result of a bet if you could repeat it many times. A ₱100 bet at 2.10 on a true 50/50 has an EV of (0.5 × ₱110) − (0.5 × ₱100) = +₱5; almost every casino bet has a negative EV. Read the full guide →
F
- Fair odds
- The price a bet would pay with no margin built in, equal to 1 ÷ the true probability. A genuine 50/50 has fair odds of 2.00; bookmakers usually offer around 1.91 instead. Read the full guide →
- Futures (outright) bet
- A bet on a long-term result such as a league winner. Because the margin is spread across every runner in the field, outright markets often carry a much bigger total margin than a single match. Read the full guide →
G
- Gambler's fallacy
- The mistaken belief that past results change the odds of independent future ones, such as thinking red is due after five blacks. Each spin of a fair wheel has exactly the same odds as the last. Read the full guide →
- Gambler's ruin
- The mathematical result that a player with limited money betting against a house edge will, given enough time, almost certainly lose it all. The more you bet relative to your bankroll, the faster it tends to happen. Read the full guide →
H
- Hit frequency
- How often a slot pays anything at all, shown as a percentage of spins. A 25% hit frequency means about one paying spin in four on average, and many of those wins are smaller than the bet. Read the full guide →
- House edge
- The share of each bet the game keeps on average over the long run. On single-zero roulette it is 2.70%, so ₱1,000 of bets has an expected loss of about ₱27. Read the full guide →
I
- Implied probability
- The chance a price suggests, worked out as 1 ÷ decimal odds. Odds of 4.00 imply 25%; if you believe the true chance is higher than that, the bet may have value. Read the full guide →
- Independent event
- A result that is not affected by earlier results. Roulette spins, dice rolls and RNG slot spins are all independent, which is why patterns in past results predict nothing. Read the full guide →
K
- Kelly criterion
- A formula for sizing a bet when you believe you have an edge: stake = (b × p − q) ÷ b, where b is the decimal odds minus 1. At odds of 2.10 with a true 50% chance it suggests 4.5% of your bankroll; most bettors use a fraction of that. Read the full guide →
- Keno
- A lottery-style casino game where you pick numbers and the game draws 20 of 80. It usually carries one of the highest house edges in the casino, often well above 20%. Read the full guide →
L
- Law of large numbers
- The principle that results move closer to their expected average as the number of bets grows. Over 10 spins anything can happen; over 100,000 spins the house edge shows through. Read the full guide →
- Line shopping
- Comparing the price of the same bet across several bookmakers and taking the best one. Winning ₱1,000 at 1.95 instead of 1.91 is ₱40 more profit for the same prediction. Read the full guide →
- Live dealer game
- A table game streamed from a studio with a real dealer and physical cards or wheel. The rules and house edge are usually the same as the RNG version of the game. Read the full guide →
M
- Margin (overround)
- The bookmaker's built-in profit, visible when the implied probabilities of all outcomes add up to more than 100%. Two outcomes priced at 1.91 each add up to 104.7%, a 4.7% overround. Read the full guide →
- Martingale
- A system that doubles the stake after every loss to recover it with one win. It cannot beat the house edge, and a short losing streak quickly hits table limits or empties a bankroll. Read the full guide →
N
- Near-miss
- A losing slot result that lands just short of a win, such as two jackpot symbols and a blank. It is just another losing outcome chosen by the RNG and says nothing about the next spin. Read the full guide →
P
- Pair Plus
- The Three Card Poker side bet that pays on a pair or better in your own hand, whatever the dealer holds. Its house edge depends on the pay table the casino uses. Read the full guide →
- Pay table
- The list of what each winning hand or symbol combination pays. In video poker the pay table sets the return: full-pay 9/6 Jacks or Better returns about 99.5% with perfect play, while 8/5 returns about 97.3%. Read the full guide →
- Progressive jackpot
- A jackpot that grows because a small part of every bet is added to it. That contribution usually comes out of the game's base return, so day-to-day RTP is often lower. Read the full guide →
- Push
- A bet that ties and returns your stake, with no win or loss. In blackjack, equal totals between you and the dealer are a push. Read the full guide →
R
- Random number generator (RNG)
- The software that decides every result in online slots and RNG table games. It produces each outcome independently, so there are no hot or cold cycles to time. Read the full guide →
- Return on investment (ROI)
- Profit divided by the total amount staked. ₱500 profit on ₱20,000 of bets is a 2.5% ROI, and you need a large sample before the figure means much. Read the full guide →
- Return to player (RTP)
- The share of all money wagered on a game that it pays back over the very long run. A 96% RTP slot returns ₱96 per ₱100 wagered across millions of spins, not to each player in each session. Read the full guide →
- Risk of ruin
- The probability of losing your whole bankroll before reaching a goal. It rises sharply as your stakes get larger relative to your bankroll. Read the full guide →
S
- Side bet
- An optional extra wager added to a main game, such as Perfect Pairs in blackjack. Side bets almost always carry a much higher house edge than the main bet. Read the full guide →
- Standard deviation
- A measure of how far results typically spread around the average. An even-money roulette bet has a standard deviation of about 1 unit per spin; a straight-up number bet has about 5.8, so results swing far more. Read the full guide →
- Surrender
- Giving up half your stake instead of playing a hand out. In Casino War, surrendering on a tie leads to a higher house edge, about 3.7%, than going to war, about 2.9%. Read the full guide →
T
- Tie bet
- A wager that two hands will tie, offered in games such as Casino War and baccarat. The high payout hides a large edge: in six-deck Casino War, a 10-to-1 tie bet has a house edge of about 18.6%. Read the full guide →
V
- Variance
- How much short-term results swing away from the expected average. High-variance games produce long losing runs and occasional big wins, even with the same house edge. Read the full guide →
- Vig (vigorish)
- Another name for the bookmaker's margin, the cut built into the odds. It is the reason two sides of an even contest are both priced below 2.00. Read the full guide →
- Volatility
- How a slot spreads its return: low-volatility games pay small amounts often, high-volatility games pay rarely but bigger. Two slots with the same RTP can feel completely different because of it. Read the full guide →
W
- Wagering requirement
- How many times you must bet a bonus before you can withdraw it. A ₱1,000 bonus at 30x means ₱30,000 of bets; at a 4% house edge the expected loss on that turnover is ₱1,200, more than the bonus itself. Read the full guide →
Final thoughts
None of these terms is a way to beat the house; they are a way to see clearly what each bet costs. Before you deposit anywhere, check the operator’s PAGCOR licence, and set a loss limit you are comfortable with. Gambling is for adults 21 and over; if it stops being fun, read our responsible gambling guide or call the NCMH crisis hotline on 1553.
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