Unit Size Calculator

A unit is a fixed percentage of the bankroll, decided in advance, so that the size of a bet never depends on how the last one went. It is the least interesting decision in betting and one of the most decisive.

Enter a bankroll and a unit percentage to see what a unit is worth, what a multi-play day risks, and how much survives a losing run of the length you should expect.

Defining The Bankroll First

Every number on this page is a percentage of one figure, so that figure has to be honest.

A bankroll is money set aside exclusively for betting that you could lose entirely without any effect on your life. Not money you expect to lose — money you could. It should be a fixed sum, decided in advance, held separately, and never topped up from other funds during a losing run. A bankroll you refill on demand is not a bankroll; it is your general finances with extra steps.

If 1% of your bankroll feels too small to be interesting, the correct conclusion is that the bankroll is too small for betting to be interesting, not that the percentage should rise. Raising the percentage does not increase the edge; it only increases the chance of never getting to collect it.

One To Two Percent, And Why

One unit equals 1–2% of the bankroll, and a normal play gets exactly one unit. Conservative bettors use 1%; aggressive ones use 3% and accept far larger swings.

Worked example. On a $2,000 bankroll at 1%, a unit is $20. A three-play day risks $60, which is 3% of the bankroll. If the largest play on that day is two units, the worst case is $120, or 6%.

That last number is the one to watch. Bettors set a sensible 1% unit and then put out eight plays a day, several of them at two units, and quietly risk 15% of the bankroll before dinner. Unit discipline is meaningless without volume discipline.

Sizing For The Losing Run You Will Get

The right way to test a unit size is not against a good week. It is against the worst run you should expect.

A 55% bettor — genuinely good — will hit a run of ten straight losses somewhere in a few thousand bets. It is not bad luck; it is arithmetic. At 1% units that run costs 10% of the bankroll and leaves you entirely functional. At 5% units it costs half the bankroll, and the bettor who then doubles down to get it back is the one who ends the season at zero.

The bankroll-in-units figure is the clearest guard rail. At 1% you have a hundred units, which is enough to survive any normal drawdown while a real edge asserts itself. At 5% you have twenty, which is fewer than one bad fortnight.

Drawdowns also arrive faster than the wins that pay for them, because losses are certain in the short run and edges only assert themselves in the long one. The bankroll projection calculator shows the full spread of outcomes for a given plan.

When To Move Off One Unit

Two rules keep tiering from turning into freelancing.

Move on edge, not on feeling. A two-unit play should mean a measurably larger edge — something like double the probability advantage of a standard play, checked in the expected value calculator or set from a Kelly fraction. It should never mean a stronger feeling about a game, and there is no such thing as a five-unit lock.

Resize the unit on a schedule, not after a result. Recalculate the unit monthly, or when the bankroll has moved by 25%, and not otherwise. Resizing after every win compounds fine but resizing after every loss is how a stake creeps upward at exactly the wrong moment. The flat betting versus percentage guide covers the trade-off between the two approaches, and unit sizing covers the tiering question in more detail.

Frequently Asked Questions