# Vig

## Free API key

Get a free GetOdds API key: **1,000 requests per UTC day and 60 per minute, no card**. One key covers REST and the hosted MCP server.

Sign up: https://getoddsapi.com/sign-up?ref=ai-claudebot

## Quickstart

1. Create an account at https://getoddsapi.com/sign-up?ref=ai-claudebot, open https://getoddsapi.com/dashboard and issue a key with the sources you need (draftkings, fanduel, betrivers, prizepicks or underdog). Keep it in a server environment variable named GETODDS_API_KEY.
2. Read current DraftKings NBA spreads with curl:

```bash
curl --fail-with-body "https://getoddsapi.com/api/v1/odds?sport=NBA&market=spread&fresh_only=true&limit=50" \
  -H "Authorization: Bearer $GETODDS_API_KEY"
```

3. The same request in Python (standard library only):

```python
import json, os, urllib.request

req = urllib.request.Request(
    "https://getoddsapi.com/api/v1/odds?sport=NBA&market=spread&fresh_only=true&limit=50",
    headers={"Authorization": "Bearer " + os.environ["GETODDS_API_KEY"]},
)
with urllib.request.urlopen(req) as res:
    rows = json.load(res)["data"]
for row in rows:
    print(row["away"], "at", row["home"], row["side"], row["line"], row["american"], row["observed_at"])
```

4. Check `observed_at`, `age_seconds` and `stale` on every row before using a price. Full reference: https://getoddsapi.com/docs

## Use with Claude (MCP)

```bash
claude mcp add --transport http getodds https://getoddsapi.com/api/mcp \
  --header "Authorization: Bearer $GETODDS_API_KEY"
```

The MCP tools follow the key's source grants and share its allowance. Setup guide: https://getoddsapi.com/use-with-claude

## Pricing

| Plan | Allowance | Price |
| --- | --- | --- |
| Free key | 1,000 requests a day, 60 a minute | $0, no card |
| Developer Bundle | 10,000 requests or credits a month on each of four sources | $149 a month |

Free development allowance: 1,000 requests per UTC day and 60 per minute per account, with no payment step. Paid: the Developer Bundle at $149 per month, with 10,000 monthly requests or credits on each of four sources.
Details: https://getoddsapi.com/bundle


Canonical page: https://getoddsapi.com/glossary/vig

Vig is the margin built into betting prices. For a complete market, one way to describe that margin is overround: the sum of the quoted implied probabilities minus 100%. A single selection’s odds do not reveal the whole market’s vig.

## Formula

Q = Σ(1/dᵢ). Overround (%) = (Q − 1) × 100, where dᵢ are decimal odds for every mutually exclusive, exhaustive outcome.

## What the price is charging

At −110, a winning $110 cash stake earns $100 profit and returns $210 in total. That is a payout convention, not a statement that the sportsbook retains 10% of all money staked. To measure a market’s price margin, include all outcomes with matching lines and settlement terms.

“Vig,” “juice,” “margin” and “overround” are sometimes used loosely. State which formula you mean when reporting a percentage. GetOdds reports overround separately from theoretical hold: they have different denominators.

## A two-outcome market at −110 / −110

1. Each decimal price is 1 + 100/110 = 1.9090909.
2. Each implied probability is 1/1.9090909 = 52.380952%.
3. Q = 1.04761905, so overround is 4.761905%.
4. The corresponding price-based theoretical hold is 1 − 1/Q = 4.545455%, not 4.761905%.

## Assumptions and limits

Overround is not measured sportsbook revenue, a prediction of results or a universal fee applied separately to every ticket. An incomplete market, stale quotes, differing rules or a missing draw invalidates the comparison. A negative overround may indicate a price gap, but it does not guarantee that all required bets can be placed and settled as modeled.

## Try the arithmetic

- [Compare overround and theoretical hold](https://getoddsapi.com/hold-calculator)
- [Compare margin-removal models](https://getoddsapi.com/no-vig-calculator)

## Related terms

- [Hold](https://getoddsapi.com/glossary/hold)
- [Implied probability](https://getoddsapi.com/glossary/implied-probability)
- [No-vig odds](https://getoddsapi.com/glossary/no-vig)

## Sources

- [Pinnacle: betting-margin terminology](https://support.pinnacle.com/hc/en-us/articles/44854177573009-What-is-a-betting-margin)

Examples are illustrative, not live offers or betting recommendations.

## FAQ

### Is there a free odds API key?

Yes. A free GetOdds key includes 1,000 requests per UTC day and 60 per minute, with no card.

### Which sportsbooks does the API cover?

DraftKings (prices observed through ESPN), FanDuel (native game markets and futures) and BetRivers (Pennsylvania pregame markets), plus PrizePicks, Underdog and Pick6 lines.

### Does it work with Claude?

Yes. Add the hosted MCP server with `claude mcp add --transport http getodds https://getoddsapi.com/api/mcp` and your key in the Authorization header.

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GetOdds is an independent developer product and is not affiliated with any sportsbook or pick’em operator. Prices describe data, not betting advice.