The number that means nothing on its own
Every tipster advertisement leads with a strike rate. Very few lead with the average price, and that omission is the entire trick.
A 55% win rate is excellent at odds of 2.10 and a slow, guaranteed loss at 1.70. The same percentage, two opposite outcomes. Win rate only becomes information once you know what you were paid for the wins.
Break-even, the number to memorise
The threshold is simply the inverse of the decimal odds. At 2.00 you need 50%. At 1.80 you need 55.6%. At 1.70 you need 58.8%. At 1.50 you need 66.7%.
So a bettor winning 55% of their bets at an average price of 1.70 is losing roughly 6.5% of everything they stake, however good the strike rate sounds. Run your own average price through the break-even win rate calculator and you have your target β anything below it is a leak, no matter how many green ticks are in the record.
Where the gap goes
The difference between 50% at 2.00 and 55.6% at 1.80 is the bookmaker's margin. Fair even-money odds on a coin flip are 2.00 on each side; a book offering 1.90 each way has built in about 5.3% of overround, and that is the fee for using the market.
You can measure it on any market you care about with the bookmaker margin calculator, and see the underlying fair prices with no-vig fair odds. Bettors who shop for the best price on every bet are not being fussy β they are cutting the only cost they can directly control.
Why ROI is the honest metric
Return on investment folds strike rate and price into one number: profit divided by total staked. A bettor at 32% from 3.50 average odds and one at 58% from 1.80 can post identical ROI, and ROI is what actually pays.
Track it per bet rather than per week, and over a meaningful sample β a few dozen bets tell you very little. The ROI tracker handles the bookkeeping, and bookmaker P&L tracker breaks it down per account, which frequently reveals that one book is quietly responsible for most of the damage.
The number that beats both
ROI still takes hundreds of bets to stabilise. Closing line value converges much faster, because it measures each decision against the market's final verdict rather than against a coin flip.
If you consistently take prices better than the close, positive ROI tends to follow. If you do not, a good-looking win rate is a story about variance rather than skill. The CLV calculator is the fastest honest read on whether a method is working β and the least flattering, which is rather the point.