Unit size calculator: a betting unit as a percent of bankroll

The unit size calculator turns a bankroll and a unit percentage into a dollar amount. Enter your bankroll and a unit between 1% and 5%. It shows the unit in dollars, how many losses in a row a flat unit covers before the bankroll is used up, and the bankroll left after ten losses. It is arithmetic only.

One unit in dollars

$30.00

Losses in a row a flat unit covers

33

Left after those losses

$10.00

Bankroll after 10 losses, flat unit

$700.00

Bankroll after 10 losses, unit re-set each time

$737.42

Next unit after those 10 losses, re-set

$22.12

A 3% unit on $1,000.00 is $30.00. At a flat $30.00, 33 losses in a row use $990.00 and leave $10.00. After 10 losses the bankroll is $700.00 with a flat unit, or $737.42 if the unit is re-set to 3% of what is left each time.

Units are commonly set between 1% and 5% of a bankroll. The size is a choice and this page does not recommend one. It shows arithmetic only, and the count of losses says nothing about how likely a losing run is.

The unit formulas

unit = bankroll × unit %

losses covered = floor(100 ÷ unit %)

A 3% unit on $1,000 is 1,000 × 0.03 = $30. With a flat dollar unit, the straight losses covered are the bankroll divided by the unit, rounded down, and that is 100 ÷ the unit percent whatever the bankroll is. If the unit is re-set after every loss, the bankroll after n losses is bankroll × (1 − unit %) ^ n, which shrinks but never reaches zero.

Worked example

A $1,000 bankroll at a 3% unit gives a unit of $30. At a flat $30, 33 losses in a row use $990 and leave $10, because 100 ÷ 3 is 33.3. After 10 losses at a flat $30, the bankroll is $700. If the unit is re-set to 3% of what is left after each loss, 10 losses leave $737.42 and the next unit is $22.12.

Questions

What is a unit in sports betting?

A unit is a fixed amount used to size bets, so stakes are written as multiples of it (1 unit, 2 units) instead of dollars. It is usually set as a percent of the bankroll, most often between 1% and 5%. The size is a choice, and this page does not recommend a percent.

Why is a unit a percent of the bankroll?

A unit set as a percent of the bankroll scales with it. The same percent covers the same number of losses in a row whether the bankroll is $200 or $20,000. A fixed dollar unit does not: $50 covers 4 losses on $200 and 400 on $20,000. The percent ties the size of a bet to the money behind it.

How many losses in a row does a bankroll cover?

At a flat unit it is floor(100 ÷ unit %): 100 at 1%, 50 at 2%, 33 at 3%, 25 at 4% and 20 at 5%. Real results are not this tidy. The count shows how the unit percent sets the number of losses a bankroll covers if every bet loses, and says nothing about how likely that is.

What every number on a betting line means · Responsible gambling · 21+ only. Gamble responsibly.