Kelly only works if you update your bankroll constantly. Your bet size is a percentage of your current bankroll, not your starting bankroll. If you're up 30% on the season, your bets should be 30% bigger. If you're down 20%, your bets must shrink by 20%.
Every Sunday (or whatever day ends your betting week), calculate your total available betting funds. This is your new bankroll. Adjust all bet sizing accordingly.
| Week | Starting Bankroll | Win/Loss | New Bankroll | 5% Bet Size |
|---|---|---|---|---|
| Week 1 | $5,000 | +$300 | $5,300 | $265 |
| Week 2 | $5,300 | -$150 | $5,150 | $258 |
| Week 3 | $5,150 | +$400 | $5,550 | $278 |
| Week 4 | $5,550 | +$200 | $5,750 | $288 |
Only money you can afford to lose. Not rent. Not emergency funds. Not money you'll need next month. Your betting bankroll is completely separate from your living expenses.
If Kelly says bet 4% and you're using half Kelly, that's 2% of your current bankroll. If your bankroll is $6,000, your bet is $120. Recalculate this every week as your bankroll changes.
Most profitable bettors grow their bankroll slowly. A 10-15% increase over a full season is excellent. If you're up 50% in two months, you're either getting lucky or taking too much risk. Slow and steady wins.