expected_value: expected value, break-even and edge from your own probability
expected_value takes odds, their format and your own estimate of the win probability as a percent from 0 to 100, plus an optional stake that defaults to 100. It returns the expected value, the break-even probability and the edge. The probability is your input, not a prediction by BetsBeats, and a positive result describes the assumption you made, not what will happen.
Examples are real responses from the live server, captured on 1 November 2026.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
odds | string | yes | The odds value as a string, for example "-110", "1.91" or "10/11". |
format | american | decimal | fractional | yes | The format of the odds: american, decimal or fractional. |
win_probability_percent | number | yes | Your estimated chance of winning, from 0 to 100, exclusive. |
stake | number | no | The stake used for the expected value amount. Defaults to 100. |
What to ask your assistant
Ask: Use BetsBeats to compute the expected value of -110 odds if I think the chance of winning is 55 percent, on a stake of 100.
Example request
Send a tools/call request to the endpoint with the tool name expected_value and these arguments.
{ "odds": "-110", "format": "american", "win_probability_percent": 55, "stake": 100 }Real response
A real response. The tool echoes the decimal odds it derived and the probability as a fraction.
{
"decimal_odds": 1.9091,
"win_probability": 0.55,
"break_even_probability": 0.52381,
"edge": 0.02619,
"stake": 100,
"expected_value": 5,
"expected_value_per_unit": 0.05,
"positive_ev": true,
"notice": "For adults 21+ only. Entertainment and analysis; no wins are promised and past results do not predict future ones. BetsBeats does not take bets."
}The math
- The odds are first converted to decimal, as in convert_odds. -110 is 1.9091.
- EV = stake x (p x (decimal - 1) - (1 - p)), with p as a fraction. Break-even probability = 1 / decimal. Edge = p - break-even.
- Worked example: p = 0.55 and decimal 1.9091 give 0.55 x 0.9091 - 0.45, which is about 0.05, so EV is about 5.00 on a stake of 100. Break-even is 0.52381 and the edge is 0.02619.
- expected_value_per_unit is EV divided by stake. positive_ev is true when EV is above zero.
Errors and edge cases
A value that is not a number returns an error result (isError true) with a plain message.
{ "odds": "x", "format": "american", "win_probability_percent": 55 }"'x' is not a number."Notes
- win_probability_percent is yours. Change it and the answer changes; the tool does not estimate it.
- Positive EV is an average over many repeated bets at the probability you assumed. It says nothing about any single bet.
- The tool does not look up odds, lines or teams.
Questions
Where does the win probability come from?
From you. If you use a BetsBeats pick as an input, that is your choice. The tool only does the arithmetic.
What is the break-even probability?
The win probability at which expected value is zero: 1 divided by the decimal odds. At -110 it is 0.52381.
Is there a calculator on the site?
Yes, the expected value calculator at /expected-value-calculator does the same sum in the browser.
The other tools
Keep going
Today's free pick, for your email
Team, bet, price and the hash it was sealed under, on this page the moment you send. Lose or win, it stays public.
or by email
Public record of the main pick, losses included: 115 won, 44 lost. See every pick
One free pick a day by email until you unsubscribe, in one click. 21+.
21+. Entertainment and analysis, not financial advice. BetsBeats sells information and takes no bets. The server is read-only: it cannot place a bet or move money. No pick is certain, past results do not predict future ones, and nothing here promises a win or a profit. If gambling stops being fun, see /responsible.