Buyer's guide

What should a prediction market arbitrage scanner cost?

Arbitrage scanners for Kalshi and Polymarket range from free to about $2,000 a year, with some sold only as one upfront annual payment. The price only makes sense next to the profit real spreads pay, so here is that math, the questions to ask before paying, and where ArbTrader fits. Prices checked October 2026.

Start with what spreads really pay

Real cross-platform spreads that clear fees are usually small: about 0.5% to 3% per trade after fees, and your money is tied up until the event settles. Double-digit gaps do show up on screens, but they are almost always a stale price on one side, a market with a few dollars for sale, or two events whose rules don't match.

So the useful question is how much you'd have to trade just to earn back the subscription:

"Trades needed" is the total dollars of filled spreads over the year before you're ahead of the subscription. Rounded to the nearest $100. Illustrative; your returns depend on what fills.

At 2% net, a $1,997 plan needs about $99,800 of filled spreads in a year before you make a dollar. For most traders starting with a few hundred or a few thousand dollars, that takes many rounds of capital that is often locked up for days or weeks.

Questions to ask before you pay

1. Can I pay monthly, and is there a trial? Annual-only plans with no stated refund policy put the whole risk on you before you've seen a single spread fill.
2. Does the profit include every platform's fees? Kalshi and Polymarket US both charge takers. A 3¢ gap near even odds can lose money once both fees are counted (see the calculator).
3. Does it show how much is for sale? A 6% spread with $4 behind it pays 24 cents. The real profit is the gap times the size you can actually buy.
4. Does it tell you how fresh the price is? Most "huge" gaps are one side that hasn't updated. A scanner should show when each price was last seen and flag spreads that vanished when someone tried them.
5. Does it work where you live? Polymarket's international site isn't available to US users. If you're in the US, the tool should support Kalshi and Polymarket US.
6. What does the guarantee actually promise? "ROI guarantees" are often extra months of access, not money back. Read the wording.
7. Who places the trades? Some tools only show the spread and you click through to each site; others place both sides for you. Speed matters, since most gaps last seconds to minutes.

Where ArbTrader fits

When a pricier tool can still make sense

Expensive plans sometimes bundle things a low-cost scanner doesn't: a private community, one-to-one coaching, position and exit tracking, or extra crypto-native venues outside the US. If you trade large size and want those, the math in the table above can work for you. If you're starting small, pay for the scanner, not the bundle, and keep the difference as trading capital.

Common questions

How much does a prediction market arbitrage scanner cost?

From free to about $2,000 a year as of October 2026. ArbTrader has a free plan and paid plans at $19.99 and $24.99 a month, billed monthly.

Is a $2,000 a year arbitrage scanner worth it?

Only if you trade enough. Real spreads usually net about 0.5% to 3% after fees, so at 2% you'd need roughly $100,000 of filled spreads in a year to earn back $2,000.

Why do some scanners show 10% or bigger arbitrage gaps?

Most are a stale price on one side, a market with very little for sale, or two markets whose settlement rules differ. Check how fresh each price is and how much you can actually buy before trading.