Kelly Criterion Calculator – Optimize Your Bet Size with Batery

Kelly Criterion Calculator tells you what fraction of bankroll to stake for the safe amount of the bet. Here is how it works in the simple terms:

For decimal odds

and your win probability

: set

b = D - 1

and

q = 1 - p

The optimal fraction of your bankroll or Kelly fraction is:

f = (bp - q) / b

is less than or equal to zero -

do not bet

. In practice most disciplined players use fractional Kelly for example one half or one third Kelly to reduce drawdowns.

Why Kelly Criterion matters

Kelly maximizes long run logarithmic growth of your bankroll under ideal assumptions which include accurate

, known odds, and independent bets. That objective is stricter than the highest average profit. It favors paths that avoid catastrophic risk even when they look conservative in the short run.

Kelly is a sizing rule, not a prediction engine. It does not tell you what to bet on. It tells you how much to stake once you believe you have an edge.

The formula you actually use

Most India facing bookings and many titles in our casino quote decimal odds. Convert once, then apply the rule:

Decimal odds
D
to net multiplier b which equals
D - 1
.
Your model gives win probability p, then q equals
1 - p
.
Kelly fraction
f*
equals
(bp - q)
divided by
b
.
Even money special case: if
D
equals 2.00 so b equals 1, then
f*
equals
2p - 1
.

The whole interpretation - stake f* of your current bankroll. If the fraction is negative, skip the bet. Simple rule: if there is no edge, there is no bet.

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How to estimate your edge without fooling yourself

Kelly only works if

is realistic. Use one of these paths and be conservative if you are unsure.

Model versus price.
Build a probability model and compare with market price. Decimal odds imply raw probability 1 divided by
D
, but books include margin. Normalize the quoted probabilities to approximate fair before comparing.
Historical hit rates.
If the event class is stable and your selection method is consistent, long run hit rate can serve as
p
. Beware of drift and selection bias.
Blend.
Start with model p, then shrink toward the market to avoid overconfidence.

How to estimate your edge without fooling yourself

When in doubt, down weight your

and use fractional Kelly. Overestimating

is the fastest way to turn a good rule into bad results.

Worked examples with decimal odds

Example A
- Positive edge

Bankroll

equals 100,000 rupees.

Decimal odds

equals 2.20, so

equals 1.20.

Your estimate

equals 0.50, so

equals 0.50.

equals (1.20 times 0.50 minus 0.50) divided by 1.20 which is about 0.0833.

Stake about 8.33 percent of bankroll which is 8,330 rupees at full Kelly. One half Kelly would be about 4,165 rupees.

Example B
- No edge

equals 1.80 so b equals 0.80 and

equals 0.52,

equals 0.48.

equals (0.80 times 0.52 minus 0.48) divided by 0.80 which is negative 0.08.

Negative means do not bet.

Example C
- Small edge with a tame variance

equals 3.00 so

equals 2 and

equals 0.37.

equals (2 times 0.37 minus 0.63) divided by 2 which is 0.055.

Full Kelly equals 5.5 percent. Many professionals choose one third to one half Kelly here because higher odds amplify variance.

Fractional Kelly Criterion for the real world control

Full Kelly is optimal only if your inputs are perfect and you can tolerate volatility. In real markets most disciplined players use a fraction. Half Kelly or one third Kelly often keeps most of the growth while cutting drawdowns.

Use smaller fractions when your

is uncertain, when odds are long, or when selections are correlated. Think of fractional Kelly as a confidence dial.

Fractional Kelly Criterion for the real world control

Session workflow

We’ve prepared your step-by-step easy plan that can help you process all the necessary calculations.

Define bankroll. Keep one pool per strategy. Do not mix funds.
Price the event. Get
D
and compute
b
equals
D - 1
.
Estimate p. Use a model with sanity checks. Shrink if unsure.
Compute
f*
. If f* is less than or equal to zero, skip. If positive, choose a Kelly fraction c in the interval 0 to 1 and stake c times
f*
times
B
.
Update bankroll after each result. The next stake scales automatically.
Log outcomes and revisit assumptions weekly. If variance feels punishing, lower c or tighten your selection filter.

Two rails make the habit robust. Set a daily loss cap that protects tomorrow bankroll and a profit bank out rule that books wins instead of compounding tilt.

Practical pitfalls and how to dodge them

Here are some tips to consider double checking while making calculations.

Misestimated p
. Use conservative inputs and fractional Kelly.
Moving price.
If the market moves, recompute before staking.
Bankroll leakage.
Do not mix strategies or add side bets without resizing.
Correlation.
Parlays or related outcomes inflate risk. Size smaller.
Limits and liquidity.
You may not always get full size. Avoid chasing into worse prices.
Psychology.
If swings bother you, cut to one quarter or one half Kelly.

Kelly quick calc with decimal odds

Firstly

Input bankroll

, decimal odds

, and your

. Then compute

equals

D - 1

and

equals

1 - p

. After that calculate -

equals

(bp - q)

divided by

. The decision should be made If

is less than or equal to zero, then the result passes. Any else stake c times

times

with c in 0 to 1.

For your consideration

Copy ready template for your notes:

Bankroll today B = ____ . Odds D = ____ . b = D - 1. Model p = ____ . q = 1 - p. Kelly f* = (b p - q) / b = ____ . Fraction c = ____ . Stake = c times f* times B = ____ . If f* is negative, no bet. Update B after result.