First Principles Plays
Tools

Bankroll, units, expectation

Three calculators, one rule underneath them all: decide what you can lose, then let the math set the bet. Nothing here predicts your results. It just shows you the arithmetic of the inputs you choose.

Tool 1

Bankroll builder

Start with the amount you could lose completely without it changing your life. Not the amount you would like to bet with. The amount you could watch go to zero.

This becomes your bankroll. Move exactly this amount into a betting account and never add to it.
Our standard is 5 units (5%). Walters' rule is 1 to 3 units. Slide left for the conservative version.
Highest conviction only. A press should be rare. If you are pressing every week, you are not pressing, you are just betting bigger.
Bankroll$100,000
Standard play$5,000
Press play (rare)$7,500
Losses in a row to be down 25%5
Losses in a row to be down 50%10
Walters sizing (1% to 3%) on this bankroll$1,000 to $3,000
How to use the number. Flat bet the standard play on every normal pick. Do not change the size after a win or a loss. At the start of each month, recompute your bankroll from the actual balance and resize. If the balance ever hits zero, you are done; the whole point of the number was that you could afford that outcome.
Tool 2

Unit sizer

A unit is a fixed slice of your bankroll so that bettors with different bankrolls can talk about bets the same way. We use the standard definition: 1 unit = 1% of bankroll. A standard play is 5 units. A press play, reserved for the rare highest conviction spot, is 7.5 units. A small play, when the handicapper likes a side but not enough for full size, is 1 unit.

One unit (1% of bankroll)$1,000
Standard play (5 units)$5,000
Press play (7.5 units)$7,500
Walters max (3 units)$3,000
That bet in units5.0u
That bet as % of bankroll5.0%
Straight talk on 5 units. Our 5 unit standard and 7.5 unit press are well above what the money management chapters in Walters' book recommend (1 to 3 units, 3 only for the very best spots). We size this way because a modest bankroll flat bet at 1 unit barely matters to most people and they end up ignoring the rule entirely. But understand the trade: at 5 units a 10 bet losing streak costs you half the bankroll, and streaks like that happen to good bettors every season. If that would wreck you, bet 1 to 3 units instead. Whatever you choose, the number is fixed before the week starts.
Tool 3

Expectation calculator

Set a bet size, how many bets you make a month, the win rate you honestly believe you can sustain and the average price you are getting. It shows what that produces on paper, and how likely a losing month is anyway.

Be honest. 52.38% is break-even at -110. Sustained 55 to 57% is elite.
-110 is standard. Enter +120 style numbers for underdogs.
Profit per winning bet$4,545
Expected wins / losses per month26 / 19
Winnings$118,182
Losses$95,000
Net per month (on paper)$23,182
Break-even win rate at these odds52.38%
Return on money risked+5.2%
Chance of a losing month anyway27%
This is not a forecast. The "net per month" line is what the arithmetic produces if your win rate holds exactly. It will not hold exactly. Months swing hard, win rates drift, and most bettors overestimate their win rate by several points, which turns a paper profit into a real loss. We do not guarantee any returns. The most likely long-run outcome for a typical bettor is losing the whole bankroll. Only play with money you can afford to lose.
Reality check at the same bet size.