Prediction Market No-Vig Advantage: Why Explicit Fees Beat Hidden Margins
Prediction market fees cost 40-60% less than sportsbook vig at most price points. 4 worked examples show exactly where the savings hide.
Sportsbooks and prediction markets both take a cut. The difference is how they take it. Sportsbooks bake their margin into the odds, making it invisible unless you do the math. Prediction markets charge explicit fees on profits. That structural difference saves traders 40-60% on transaction costs at most price points.
This is not a minor detail. Over hundreds of trades, the gap between hidden vig and explicit fees determines whether a slight edge compounds into real returns or gets eaten alive.
What Is Vig and How Do Sportsbooks Hide It?
Vig (short for vigorish) is the sportsbook's built-in margin. The standard American odds line is -110 on both sides. That means you risk $110 to win $100 on either outcome.
The math: both sides of a -110 line imply 52.4% probability. Add them up: 52.4% + 52.4% = 104.8%. That extra 4.8% is the vig. The true probabilities sum to 100%, but the sportsbook's implied probabilities sum to 104.8%.
What the bettor actually pays: On a -110 line, you risk $110 to win $100. Your breakeven win rate is 52.38%. If the true probability is 50%, the sportsbook extracts $2.38 per $110 wagered, or about 2.17% of your stake.
But here is the part most bettors miss: the vig is not evenly distributed. On lopsided lines like -300/+250, the vig load shifts. Use the De-Vig Calculator to strip the margin from any line and see the true implied probabilities. The Hold Calculator shows the total margin across both sides.
Sportsbooks prefer this structure because bettors never see a line item called "fee." The cost is embedded in worse odds.
How Prediction Market Fees Work
Prediction markets charge differently. You buy and sell contracts at market prices, and the platform takes a percentage of your net profit.
Kalshi charges approximately 7% of profits (with a fee cap that reduces the effective rate on larger wins). Polymarket charges roughly 2% of net profits.
The key distinction: you only pay when you win. If you buy a contract at $0.60 and it resolves to $0.00, you lose your $0.60 and pay zero fees. The sportsbook takes its vig win or lose because the cost is baked into the price you accept.
Run exact fee comparisons through the Prediction Market Fee Calculator. For a complete breakdown of how each platform structures fees, read Prediction Market Fees Explained.
4 Worked Examples at Different Price Points
The advantage is not uniform. It depends on the contract price, your win rate, and the specific platform. Here are four scenarios comparing standard -110 sportsbook vig against Kalshi (7% profit fee) and Polymarket (2% profit fee).
All examples assume a $100 stake and a fair 50/50 event for the sportsbook comparison. For prediction markets, we use the equivalent contract price of $0.50.
Example 1: Even-Money Event ($0.50 Contract)
Sportsbook (-110 both sides):
- Risk $110 to win $100. Effective cost: $10 per $110 wagered = 4.55% of stake.
- Per $100 risked: you pay about $4.55 in embedded vig.
Kalshi ($0.50 contract, 100 shares = $50 risked, win $50 profit):
- Fee on win: 7% × $50 = $3.50
- Fee as % of amount risked: $3.50 / $50 = 7.0%
- But you only pay when you win (50% of the time). Expected fee per trade: $1.75 / $50 = 3.5%
Polymarket ($0.50 contract, same structure):
- Fee on win: 2% × $50 = $1.00
- Expected fee per trade: $0.50 / $50 = 1.0%
Cost comparison per $100 equivalent risk:
| Venue | Effective Cost | Savings vs Sportsbook |
|---|---|---|
| Sportsbook (-110) | ~$4.55 | Baseline |
| Kalshi | ~$3.50 | 23% cheaper |
| Polymarket | ~$1.00 | 78% cheaper |
At even money, prediction markets already win. Polymarket's 2% profit fee is dramatically cheaper.
Example 2: Favorite at $0.75 Contract (-300 Equivalent)
This is where things get interesting. Sportsbook lines on heavy favorites carry disproportionate vig.
Sportsbook (-300/+250):
- Implied probabilities: 75% and 28.6%. Total: 103.6%. Vig: 3.6%.
- Bet $300 to win $100 on the favorite. Breakeven probability: 75%. If true probability is 72.5% (after de-vigging), the vig costs roughly $7.50 per $300 wagered = 2.5%.
Kalshi ($0.75 contract, 100 shares = $75 risked, win $25 profit):
- Fee on win: 7% × $25 = $1.75
- Win probability ~75%. Expected fee: $1.31 per trade.
- Expected fee as % of risk: $1.31 / $75 = 1.75%
Polymarket (same structure):
- Fee on win: 2% × $25 = $0.50
- Expected fee: $0.375 / $75 = 0.5%
At the $0.75 price point, prediction market fees shrink because the profit per contract is smaller, and fees are only charged on profit.
Example 3: Longshot at $0.20 Contract (+400 Equivalent)
Sportsbook (+400/-500):
- Total implied: 103.3%. Vig: 3.3%.
- Risk $100 to win $400. Embedded vig costs about $6 per $100 on the longshot side.
Kalshi ($0.20 contract, 100 shares = $20 risked, win $80 profit):
- Fee on win: 7% × $80 = $5.60
- Win probability ~20%. Expected fee: $1.12 per trade.
- Expected fee as % of risk: $1.12 / $20 = 5.6%
Polymarket (same structure):
- Fee on win: 2% × $80 = $1.60
- Expected fee: $0.32 / $20 = 1.6%
Longshots on Kalshi start to narrow the gap because the profit-based fee is applied to a larger payout. Polymarket still wins comfortably.
Example 4: Deep Favorite at $0.90 Contract
Sportsbook (-900/+700):
- Total implied: 102.7%. But the favorite side carries outsized vig.
- Risk $900 to win $100. Effective cost on the favorite: roughly $20 per $900 = 2.2%.
Kalshi ($0.90 contract, 100 shares = $90 risked, win $10 profit):
- Fee on win: 7% × $10 = $0.70
- Win probability ~90%. Expected fee: $0.63 per trade.
- Expected fee as % of risk: $0.63 / $90 = 0.70%
Polymarket:
- Fee on win: 2% × $10 = $0.20
- Expected fee: $0.18 / $90 = 0.20%
Deep favorites show the prediction market advantage at its strongest. Fees on small profits are tiny. The sportsbook still charges full vig on the entire amount risked.
The Pattern
The prediction market no-vig advantage follows a clear pattern:
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Fees scale with profit, not with stake. Sportsbook vig is proportional to the amount wagered. Prediction market fees are proportional to profit. On favorites (high-probability contracts), profits are small relative to stake, so fees are tiny.
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You only pay when you win. This reduces the expected cost per trade by the probability of losing. A 90% winner pays fees 90% of the time, but those fees are on the small 10% profit margin.
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The advantage is largest on favorites and smallest on longshots. Longshot contracts generate large profits relative to stake, so percentage-of-profit fees add up.
Where the Advantage Breaks Down
The prediction market no-vig advantage is real, but it is not universal. Three situations erode or eliminate it.
Illiquid Markets and Wide Spreads
A market with a $0.45 bid and $0.55 ask has a 10-cent spread. That spread functions exactly like hidden vig. If the true price is $0.50, you are paying 10% just to enter the position. No fee structure saves you from a wide spread.
Before trading, check the order book depth. A 1-2 cent spread is competitive. Anything above 5 cents and you are giving back more than the fee savings. This is one of the common prediction market mistakes that destroys edge.
Exotic or Thinly Traded Contracts
Sportsbooks offer sharp, liquid lines on NFL spreads and NBA totals. Prediction markets may list the same event but with 10x wider spreads. The fee structure advantage means nothing if the market is too thin to trade at a fair price.
Multiple Trades and Churning
If you trade in and out of positions frequently, prediction market fees apply to each profitable exit. A sportsbook bet is one-and-done: you pay vig once. A trader who buys at $0.50, sells at $0.55, buys back at $0.52, and sells at $0.58 pays fees on each profitable leg. High-frequency position changes can erode the structural advantage.
For a broader comparison of when each venue makes sense, read Sportsbook vs Prediction Market. If you are looking for price discrepancies between platforms, the Arbitrage Calculator quantifies cross-venue edges. Read more in Cross-Platform Arbitrage.
How to Calculate Your Actual Cost
For any specific trade, the process is straightforward:
- Sportsbook side: Enter the odds into the De-Vig Calculator to find the true probability and the vig percentage.
- Prediction market side: Enter the contract price and platform into the Fee Calculator to see the expected fee.
- Compare the effective cost per dollar risked. The venue with the lower number is where you should trade.
Do this for every event you trade on both venues. The savings are not theoretical. They are dollars that stay in your bankroll instead of going to the house.
The Bottom Line
Prediction markets charge less than sportsbooks for the same exposure at most price points. The structural reason is simple: percentage-of-profit fees with a pay-only-when-you-win model produce lower expected costs than vig baked into every line. The advantage ranges from roughly 20% savings on even-money events to 70%+ savings on heavy favorites, depending on the platform.
The exception is illiquid markets where wide spreads function as hidden vig. Check the spread before assuming you are getting a better deal.
Frequently asked questions
- Why are prediction market fees lower than sportsbook vig?
- Prediction markets charge a percentage of profit only when you win. Sportsbooks embed vig into the odds on every bet regardless of outcome. This structural difference means prediction market traders pay 40-60% less in transaction costs at most price points.
- Do prediction markets always have lower costs than sportsbooks?
- No. In illiquid prediction markets with wide bid-ask spreads, the spread itself acts as hidden vig. A 10-cent spread on a $0.50 contract costs more than standard sportsbook vig. Always check order book depth before trading.
- How much does Kalshi charge compared to a -110 sportsbook line?
- Kalshi charges approximately 7% of profits, only on winning trades. On a 50/50 event, this works out to about 3.5% expected cost per trade versus roughly 4.55% for a -110 sportsbook line. The savings increase on favorite contracts where profits are smaller relative to stake.
- Is the no-vig advantage bigger on favorites or longshots?
- The advantage is biggest on favorites. A $0.90 contract pays only $0.10 profit, so the fee is tiny relative to the amount risked. Longshot contracts ($0.20) generate $0.80 profit, making the percentage-of-profit fee larger relative to stake.
- How do I calculate whether a sportsbook or prediction market is cheaper for a specific bet?
- Use a de-vig calculator to find the sportsbook's true implied probability and vig percentage. Then use a fee calculator to find the prediction market's expected fee for the same event. Compare the effective cost per dollar risked. The lower number wins.