Ask a losing sports bettor how they size their bets and you'll get variations of the same answer: "I bet $50 normally, but $200 when I really like it." That instinct — betting bigger when you feel more confident — is one of the most expensive habits in recreational betting.
The units system replaces feeling with math. It's the foundation of every sustainable betting approach and the first thing any serious bettor should implement.
What Is a Unit?
A unit is a fixed percentage of your total betting bankroll. The standard is 1 unit = 1% of bankroll.
$1,000 bankroll → 1u = $10.00
$2,500 bankroll → 1u = $25.00
$5,000 bankroll → 1u = $50.00
$10,000 bankroll → 1u = $100.00
The key: the dollar amount changes as your bankroll changes. Win $500 with a $1,000 starting bankroll? Your bankroll is now $1,500, and 1u = $15. Lose $300? Your bankroll is $700, and 1u = $7. The system automatically scales — protecting you when you're down and growing your stakes when you're up.
Why Flat Dollar Betting Fails
Imagine betting $100 per game flat. You hit a cold streak — 5 losses in a row. You're down $500 on a $1,000 bankroll, 50% wiped out. Now you need to win those back at $100 per game — but psychologically, you'll probably start pressing and bet $200 "to get back faster." That's how bankrolls go to zero.
With units, the same cold streak looks different. 5 losses at 1u each = down 5 units = down $50 on a $1,000 bankroll. That's 5%. Manageable. You haven't touched your core capital and you can continue without changing behavior.
A 10-game losing streak at flat $100/game costs $1,000 — your entire bankroll if you started with $1,000. The same streak at 1u costs $100 — 10% of bankroll. The units system makes losing streaks survivable.
Standard Unit Sizes in Practice
| Bet Size | When to Use | Risk Level |
|---|---|---|
| 0.5u | Standard play, moderate confidence | Low — most common size |
| 1.0u | High confidence, strong market support | Standard |
| 1.5u | Very strong edge with movement confirmation | Elevated — use sparingly |
| 2.0u | Rare — exceptional edge only | Max recommended |
ZachAI Picks caps plays at 1.0u for standard releases. This isn't conservatism for its own sake — it reflects the reality that even high-confidence picks in a 60%+ win rate system should not risk more than 1% of bankroll per play. The edge is in volume and consistency, not in swinging big on single games.
The Stop-Loss Rule
Units also make stop-loss rules concrete and enforceable. ZachAI recommends: if you're down 3 units in a single day, stop betting for that day.
At 1% per unit, being down 3u in a day means you've lost 3% of your bankroll. That's meaningful but recoverable. Continuing to bet when you're running cold chases losses with deteriorating discipline — a guaranteed way to turn a manageable drawdown into a catastrophic one.
Tracking Units vs. Dollars
One of the most important habits in professional betting is tracking performance in units, not dollars. This does two things:
- Makes results bankroll-agnostic — a service that's up +18 units is useful information regardless of whether you bet $10/unit or $100/unit.
- Removes emotional attachment to dollar amounts — losing $200 feels devastating; losing 2 units at 1% each is just data.
When you evaluate a pick service — including ZachAI — look at units won/lost, not dollar amounts. A service bragging about "$10,000 in profits" tells you nothing about their unit sizing. A service showing +24 units over 120 plays at 1u stakes tells you everything about their edge.
Recalibrating Your Unit Size
How often should you recalculate your unit size? There are two reasonable approaches:
- Monthly recalibration — at the start of each month, calculate your current bankroll and set your unit size for the month. Simple, predictable.
- 10% threshold recalibration — recalculate whenever your bankroll moves up or down by 10% from the last set point. More responsive to actual results.
Either works. The important thing is picking one and sticking to it — not adjusting mid-streak based on emotion.
Every ZachAI pick specifies units (0.5u or 1.0u). Apply those to your personal unit size. If your bankroll is $500 and the pick is 0.5u, your bet is $2.50. If your bankroll is $10,000 it's $50. Same edge, different dollar amount — that's the system working correctly.
The Bottom Line
The units system won't make bad picks win. But it will ensure that bad stretches don't end your betting permanently, and that good stretches compound properly. It's the infrastructure that makes every other edge sustainable over time.
Set your bankroll. Define your unit. Stick to the sizes. Recalibrate monthly. That's it — the entire foundation of professional bet sizing in four sentences.