How to Track Your Sports Bets: Building a Bet Log
Related book: The Sports Investing Blueprint by Ethan Cole · Amazon
A bet log turns a pile of tickets into feedback you can use. With a few columns filled in for every bet, you can see your real return, whether you are getting good prices, and whether your stakes are staying inside your bankroll plan. This page shows what to record, how to work out units won and ROI, and why closing line value is the column worth watching most.
Want a head start? The free bankroll and line-shopping worksheet gives you a ready CSV for stakes and prices, and the American odds to implied probability table handles the conversions. Every bet on this page is a made-up example.
What to record for every bet
A simple sports betting tracker spreadsheet needs one row per bet and these columns:
- Date the bet was placed.
- Sport and league.
- Market: spread, total, moneyline or prop, plus the side you took.
- Book you placed it with.
- Odds taken, in American format.
- Closing odds on both sides, recorded when the game starts.
- Stake in units, not just dollars.
- Result: win, loss or push.
- Profit in units: the payout on a win, minus the stake on a loss, zero on a push.
Recording stakes in units keeps the log readable as your bankroll changes. If your bankroll is $2,500 and a unit is 2% of it, one unit is $50. The bankroll management and unit sizing guide covers how to pick that number.
Working out profit per bet
For a negative American price, drop the minus and call it A. A 1-unit winner pays 100 / A units. For a positive price P, a 1-unit winner pays P / 100 units. A loss costs the full stake.
- -110 winner: 100 / 110 = 10 / 11, which is 0.91 units.
- -105 winner: 100 / 105 = 20 / 21, which is 0.95 units.
- +120 winner: 120 / 100 = 1.20 units.
A sample bet log
Here are five made-up bets at 1 unit each, from made-up books. The closing odds are the final prices on your side and the other side.
| Bet | Market | Book | Odds taken | Close (your side / other) | Stake | Result | Profit |
|---|---|---|---|---|---|---|---|
| 1 | Basketball spread | Book A | -110 | -125 / +105 | 1u | Win | +0.91u |
| 2 | Football moneyline | Book B | +150 | +140 / -160 | 1u | Loss | −1.00u |
| 3 | Hockey total | Book A | -105 | -110 / -110 | 1u | Win | +0.95u |
| 4 | Baseball moneyline | Book C | +120 | +110 / -130 | 1u | Win | +1.20u |
| 5 | Basketball total | Book B | -120 | -115 / -105 | 1u | Loss | −1.00u |
Units won and ROI
Units won is the sum of the profit column. Exactly, 10 / 11 − 1 + 20 / 21 + 6 / 5 − 1 = 1,226 / 1,155, which is +1.06 units. At $50 a unit, that is $53.07.
ROI is units won divided by units staked. Five 1-unit bets means 5 units staked, so ROI = (1,226 / 1,155) ÷ 5 = 1,226 / 5,775, which is +21.23%.
Use units staked, not number of bets, once your stakes vary. A 2-unit bet counts as 2 units in the denominator.
Why CLV tells you more than win-loss
Three wins from five bets and a +21% ROI look great. The closing odds tell a more useful story. Closing line value compares the implied probability of the price you took with the no-vig closing probability on your side. The math is the same as in implied probability and the vig.
| Bet | Implied, price taken | No-vig close, your side | CLV |
|---|---|---|---|
| 1 (-110) | 11 / 21 = 52.38% | 41 / 77 = 53.25% | +0.87 pts |
| 2 (+150) | 2 / 5 = 40.00% | 65 / 161 = 40.37% | +0.37 pts |
| 3 (-105) | 21 / 41 = 51.22% | 1 / 2 = 50.00% | −1.22 pts |
| 4 (+120) | 5 / 11 = 45.45% | 230 / 503 = 45.73% | +0.27 pts |
| 5 (-120) | 6 / 11 = 54.55% | 943 / 1,846 = 51.08% | −3.46 pts |
The average CLV across the five bets is −0.63 points. Three bets beat the close, but bet 5 paid -120 for a side that closed at -115, and bet 3 paid -105 for a side that closed at a no-vig 50%. Bet 2 lost and still beat the close; bet 3 won and still lost to it.
The result column grades luck plus price. The CLV column grades the price alone, on every bet, the moment the game starts. If your average CLV stays negative over a long log, a winning record is more likely to be running ahead of your process than proof of it. If it stays positive through a cold streak, your prices are holding up even while results lag.
Sample size and variance
Five bets say almost nothing. Even a few hundred bets leave a wide range of outcomes. Take bets at -110, where the break-even rate is 11 / 21, or 52.38%. If that were your true win rate, the standard deviation of your observed win rate would be about 5.0 points over 100 bets and about 1.6 points over 1,000 bets. So a 100-bet record anywhere from about 47% to 57% is within one standard deviation of break-even.
Understanding variance covers why short records swing so far. The practical takeaway for your log: judge results over many hundreds of bets, and lean on CLV in the meantime.
Using the log for bankroll discipline
The log is also where your staking plan gets checked. A few habits keep it honest:
- Log every bet, including the ones you would rather forget. A log with gaps overstates your results.
- Check that stakes stay at your planned unit. A run of 3-unit bets after losses shows up right away in the stake column.
- Recalculate the unit on a set schedule, such as monthly, not after each win or loss.
- Compare books in the book column. If one book keeps giving you worse prices, line shopping is the fix.
Over time, positive CLV is how a positive expected value shows up bet by bet, and the stake column is what keeps you in the game long enough for it to count.
Start your log today
Download the free bankroll and line-shopping worksheet, add columns for closing odds and CLV, and keep the American odds implied probability table open for quick conversions. Record every bet, track units won, ROI and CLV, and review the whole log on a schedule rather than after each game.
For how records, price and bankroll fit together into one system, see the book.