Order Book
Which plays are available entirely on exchanges — where both sides are tradeable market prices rather than a bookmaker's offer — and what those prices really cost once the venue's fee is taken at fill.
The screen, annotated
Every column, and what its number actually means.
Kalshi and Polymarket are not bookmakers. Nobody offers you a price; other traders leave standing offers, and the list of them is the ORDER BOOK. Each rung of that list is a LEVEL: a price, and the SIZE sitting at it — how many contracts someone is actually willing to sell you there. DEPTH is how much size the book holds. A TAKER is someone who accepts an offer already resting on the book, which is what you do every time you place from this screen.
The play's return AFTER the venues' fees. Unlike the sportsbook boards, the number here has already had a real cash cost subtracted from it, which is why it looks so much smaller than a gross figure you might compute yourself. It is a percentage of the money put at risk on the whole position, not of either leg.
The fee line under the card, shown whenever a leg sits on a venue that bills separately. Read it as the deduction that turned the 4.17% the two prices imply into the badge above — the card names the deduction and deliberately prints no gross figure. TWO THINGS ABOUT IT. The fee is charged when your order FILLS, not when the market settles — you pay it whether the contract eventually wins or loses. And it is priced at the stakes in the boxes, so it grows as you type a bigger position. With no stake entered it reads "venue fee applies — enter a stake to price it".
The two legs. The price shows in whatever odds format you chose in Settings. But an exchange quotes in cents per contract, and that price is just the inverse of the decimal odds: 3.70 decimal is a 27c contract, 1.45 decimal is a 69c contract. Every contract settles at $1.00, so 27c buys a dollar of payout for 27 cents. Thinking in cents is what makes the fee formula legible.
Depth, read for you. It says how that leg's share of the plan fills down the venue's book. "fills $300 at 3.70, then 3.45" means part of it takes a second, worse level. "only $40 available" means the book ran out. It is read from a recent snapshot of the book, so it can lag a fast market. A sportsbook leg prints nothing here; its house max is in the price's hover.
The most the whole play can take while both legs still fill at prices that lock a result. When the market is thinner than the plan, the stake boxes are seeded down to it. It also appears when you type past it. It is measured on prices alone, and fees come on top, so the last dollars under the cap earn less than the badge.
A tag beside the badge when an exchange leg had no depth to read. That edge is priced at the quote, as if the book were bottomless, and the row is ranked below rows whose fill was checked. There is no depth line and no cap on these, so size them from the venue's own book.
What to put on at that venue. The boxes are linked: type into one and the other resizes so both outcomes pay the same. The card seeds them to what the market can fill, but it will not stop you typing more. Past the cap, the box's hover says "Above what the market can fill" and the capped line appears.
The outcome line under the legs, recomputed live as you type. It is AFTER FEES, and it subtracts: what comes back ($150.00 of payout less $4.32 of fees taken at fill) minus what you put in is what you keep. It can differ from the badge by a few hundredths — the badge is computed on a $100 reference plan, this line on the stakes in the boxes. One limit: it prices every dollar you type at the top quote. It does not walk the book.
On a low-hold row, what covering BOTH sides costs you — already net of the venues' fees. A positive hold is a price you pay, not a profit: covering both sides of a 1.80% market loses 1.77% of what you stake. The loss is a shade smaller because the hold is measured against the implied total and the loss against your money. Only a NEGATIVE hold is a locked return. Note the badge on such a row is the hold negated, so it can read as a green pill containing a minus sign — that minus is real.
A middle row. The first line is the two outcomes, the second is the chance of landing in the gap that you need versus the chance the market prices. Exchange middles are rarer than sportsbook ones because both venues are pricing against the same flow, and the fee is charged on both legs whichever way it lands.
Every venue's price on this same line, in place. Open it BEFORE you commit anything. On an exchange it is the only thing here that tells you whether a second-best cover exists, if the leg you planned moves while you fill the first.
When the pair was first seen at these prices. An order book changes whenever anybody trades, so a timestamp several minutes old means the level that created this row has probably already been eaten by somebody else.
The three controls that matter
Ignore everything else on a first read.
Sportsbooks (the chip list at the bottom of Filters)
Tick only the exchanges where you hold a funded, verified account. Funding is slower here than at a sportsbook. A transfer that has not cleared is the same as no account. A row you cannot fill both sides of is not an opportunity — it is a one-sided bet you took by accident.
Min edge %
On this board the figure it filters is already NET of fees, so a floor of 0.5 means half a percent you actually keep. Two warnings. Below roughly 0.5% the edge is thinner than the price move you cause by taking size, so the row is not really there. And any positive floor deletes every low-hold row at once, because a low-hold row's percentage is its hold negated and therefore negative — leave this blank when you are shopping for cheap two-sided markets.
Max quote age
Set it to 30-60, tighter than you would on a sportsbook board. A book price is an offer a company chooses to leave up; an exchange price is one trader's resting order, and it vanishes the moment somebody else takes it. Everything else on the bar — markets, dates, the event picker, the hedge odds bounds — can be left alone on a first read.
A worked example
From a real row to a placed bet, including the stake.
Four things about $1.68. First, that is the trade — not a fraction of it. The 4.17% you can see is available on $144.00 and nowhere else. The card says so, but its stake boxes will still let you type ten times that. Second, the fee IS the position. $4.32 of cost against $6.00 of gross edge means nearly three quarters of the opportunity belongs to the venues. And it is charged at fill, so you pay it even on the leg that loses. Both fees peak near 50c a contract and shrink toward the extremes. That is why a pair of mid-priced contracts that looks best on the board is usually the one fees eat whole. Third, 1.17% here against the badge's 1.15% is not a discrepancy. The badge is computed on a $100 reference plan, stakes rounded to whole cents and each fee rounded up. The two drift by hundredths. Trust the badge for ranking and your own arithmetic for the trade you actually place. Fourth, the rates. Kalshi's taker rate is 0.07. Polymarket US publishes its own, and this example charges it 0.07 too, to keep the arithmetic simple. Check the venue's fee page for the current rate. The card uses the rate TrueEdge has on file.
When it goes wrong
The price moved, a leg was voided, the row vanished. What to actually do.
You sized in dollars and typed past the cap. You wanted $1,000 on the row above, so you took 1,041 contracts a side, when only 150 were resting at 27c.
Understand what just happened before you do anything else, because the position is not the one the card described. The first 150 filled at 27c for $40.50. The remaining 891 lifted the next level, 32c, for $285.12. Your 1,041 Kalshi contracts cost $325.62, an average of 31.3c, not 27c. The 69c leg cost $718.29. You have staked $1,043.91 to collect $1,041.00 — a $2.91 loss before any fee. The fees add $15.65 at Kalshi and $15.59 at Polymarket. You have locked a $34.15 LOSS on a row that was genuinely positive at $144. The outcome line said about +$12, because it priced every dollar at 27c. Nothing recovers that once both legs fill, so the work is before. Keep the typed total at or under the capped figure. If you want more of this edge, find another row rather than a deeper level of this one. If only the Kalshi leg is on so far, stop. Size the Polymarket leg to the contracts you ACTUALLY hold — 1,041 — not to the plan you started with.
The first leg filled and the second venue's price moved before you crossed. You hold 150 Kalshi contracts at 27c and the 69c on the other side is gone.
You have a directional position you never intended. On an exchange, unlike a sportsbook, you have a real third option: sell the contracts back into the book before the game settles, at whatever someone is bidding. That exit is not free. You cross the spread the other way, and you pay the taker fee a second time — about another $2 on 150 contracts near these prices. So compare three real numbers. The cost of covering on the other side at whatever price exists now (open All books). The cost of selling out of the Kalshi leg. And the cost of holding 150 contracts to settlement, which is $40.50 at risk. Pick the cheapest deliberately. The failure mode is doing none of the three and discovering at settlement that you had a $40.50 opinion on a basketball game.
Your order has not filled. It is sitting on the book as a resting offer, and the row is still on the screen.
You placed at the quoted price instead of crossing to take it, so you are now a maker rather than a taker — an offer waiting for somebody else, not a trade. Every number on this board is priced as a taker, because taking is what crossing a spread to capture an edge actually is. An unfilled first leg is harmless: cancel it. An unfilled SECOND leg is the naked-position problem in slow motion, so cancel it and re-take at whatever is currently resting, or unwind the first leg. Do not leave it and check back — the price that fills you eventually will be the one that moved against you.
Common mistakes
The specific ways people lose money with this tool.
Reading the outcome line under the stake boxes as what a big position keeps, because it is net of fees and it moves when you type.
It takes the fee off correctly, but it prices every typed dollar at the top quote. It never walks the book. Type $1,000 into the row above and it reads about +$12. The fills that size actually gets lock a $34.15 loss. A reader who sizes off that line is reading arithmetic that never happens.
Keep the typed total at or under the capped figure, and read the depth line under each price. A second price after "then" means part of your stake fills worse than the outcome line assumes. For the fee at your size, read the fee line: it follows the boxes. Or compute it per leg: rate x contracts x price x (1 - price), at the venue's published rate. Kalshi's is 0.07; Polymarket US publishes its own.
Taking the whole percentage at whatever size you normally bet, because the price on the card is the price.
The headline price is good only for the size resting at that level. Anything past it fills at the next level, and the next. Your average price ends up worse than the one you clicked. The edge disappears fastest exactly when you take most: the worked example turns a real 4.17% into a locked $34.15 loss by taking seven times the size available. The card warns you, but it does not stop you. And a row tagged "liquidity unknown" has no depth reading at all.
Size the trade to the capped figure, or to the depth lines when no cap shows. On a "liquidity unknown" row, open the venue's own order book and read the size at the top level first. Size in CONTRACTS — the number resting there — and let the dollars fall out of that. If the level is too small to be worth the clicks, skip the row; the next one is a refresh away.
Treating a low-hold row as an arbitrage because everything on an exchange-only board looks like free money.
A positive hold is the price of covering both sides, not a return. Cover both sides of a 1.80% row and you have paid 1.80% of your stake for the privilege of a locked result — about $18 on $1,000, gone, with no outcome that gives it back. Low hold means cheap, not free.
Place a two-sided cover only when the hold is NEGATIVE — the card will read hold -0.40% and the badge will be positive. Otherwise read a low-hold row for what it is: the cheapest place on the board to take ONE side. Useful when you already have a view, or are covering a position you hold elsewhere.