# No-vig calculator

Remove a market’s margin with multiplicative, additive, power or Shin models. Enter prices for every mutually exclusive outcome to compare fair probabilities and their decimal and American equivalents. Each supported model sums to 100%. These are model-dependent estimates derived from prices, not independently verified win probabilities.

Canonical page: https://getoddsapi.com/no-vig-calculator

## 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

## Calculator


Canonical page: https://getoddsapi.com/no-vig-calculator
Markdown version: https://getoddsapi.com/no-vig-calculator.md
Language: English. Formula review date: 2026-11-06.

Remove a market’s margin with multiplicative, additive, power or Shin models. Enter prices for every mutually exclusive outcome to compare fair probabilities and their decimal and American equivalents. Each supported model sums to 100%. These are model-dependent estimates derived from prices, not independently verified win probabilities.

## Inputs

| Input | Default example | Instructions |
| --- | --- | --- |
| Outcome odds | -110,-110 | Enter 2 to 8 prices for exhaustive, mutually exclusive outcomes, separated by commas. |
| Margin-removal method | multiplicative | Different margin models can disagree, especially for longshots. Show all compares supported methods. |

## Formula

pᵢ = 1/dᵢ; S = Σpᵢ. Multiplicative: pᵢ/S. Additive: pᵢ − (S − 1)/n. Power: pᵢᵏ with Σpᵢᵏ = 1. Shin: (√(z² + 4(1 − z)pᵢ²/S) − z)/(2(1 − z)), summed to 1.

## Worked example

At −150 / +130, multiplicative probabilities are 57.9832% / 42.0168% (−138 / +138). Additive and Shin give 58.2609% / 41.7391%; power gives 58.3983% / 41.6017%. At −110 / −110, all methods return 50% / 50%.

| Result | Value | Working |
| --- | --- | --- |
| Outcome 1 fair probability | 50% | Multiplicative margin model |
| Outcome 2 fair probability | 50% | Multiplicative margin model |
| Outcome 1 fair decimal odds | 2 | 1 ÷ 0.5 |
| Outcome 1 fair American odds | 100 | American equivalent of the fair decimal price |
| Outcome 2 fair decimal odds | 2 | 1 ÷ 0.5 |
| Outcome 2 fair American odds | 100 | American equivalent of the fair decimal price |
| Outcome 1 implied probability | 52.381% | 100 ÷ quoted decimal odds |
| Outcome 2 implied probability | 52.381% | 100 ÷ quoted decimal odds |
| Implied probability sum | 104.7619% | Sum of the quoted implied probabilities |
| Overround | 4.7619% | (Implied sum − 1) × 100 |
| Theoretical hold | 4.5455% | (1 − 1 ÷ implied sum) × 100 |

## Assumptions and limits

These models allocate margin differently; none proves true win probability. Additive falls back to proportional removal if it would create nonpositive probabilities, with a warning. Shin is restricted to 0 ≤ z < 0.5. A probability sum below 100% has no positive margin to remove. Fees, settlement differences and price changes are excluded.

Inputs are supplied by the user. These calculators do not fetch live sportsbook prices, estimate a win probability, or recommend selections. Monetary examples use USD. Calculations run in the browser without an account. A shared calculation URL contains its entered numbers.

## Questions and answers

### How does the no-vig calculator work?

Remove a market’s margin with multiplicative, additive, power or Shin models. Enter prices for every mutually exclusive outcome to compare fair probabilities and their decimal and American equivalents. Each supported model sums to 100%. These are model-dependent estimates derived from prices, not independently verified win probabilities.

### What is the formula?

pᵢ = 1/dᵢ; S = Σpᵢ. Multiplicative: pᵢ/S. Additive: pᵢ − (S − 1)/n. Power: pᵢᵏ with Σpᵢᵏ = 1. Shin: (√(z² + 4(1 − z)pᵢ²/S) − z)/(2(1 − z)), summed to 1.

### Can you show a worked example?

At −150 / +130, multiplicative probabilities are 57.9832% / 42.0168% (−138 / +138). Additive and Shin give 58.2609% / 41.7391%; power gives 58.3983% / 41.6017%. At −110 / −110, all methods return 50% / 50%.

### What assumptions should I check?

These models allocate margin differently; none proves true win probability. Additive falls back to proportional removal if it would create nonpositive probabilities, with a warning. Shin is restricted to 0 ≤ z < 0.5. A probability sum below 100% has no positive margin to remove. Fees, settlement differences and price changes are excluded.

### Does the result include the original stake?

Total return includes a cash stake; net profit subtracts it. A stake-not-returned bonus is explicitly treated differently. Probability and margin outputs are percentages, not cash payouts.

### Can I share my calculation?

Use Copy link to share the current inputs. The URL contains your entered numbers. Calculations run in your browser and do not require an account.

## Embedding

Embed: https://getoddsapi.com/embed/no-vig-calculator
Keep a visible attribution link to the canonical explanation. Embed pages are noindex; use the canonical page for indexing and citations.

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Independent educational product, not affiliated with any sportsbook or pick’em operator. Results are arithmetic, not predictions or betting advice. Only participate where lawful and within limits you can afford.
Responsible gambling resources: https://www.ncpgambling.org/