How is profit calculated on Polymarket?

Shares received = stake ÷ price. Each winning share redeems for exactly $1. Profit = shares − stake − fee. At 55¢, $100 buys about 181.8 shares, which redeem for $181.82, a gross profit of $81.82 before any fee.

What happens if I buy NO instead of YES?

Buying NO is equivalent to buying YES at the complementary price. If YES trades at 55¢, NO costs 45¢. A $100 NO position buys about 222.2 shares which also redeem for $1 each if the market resolves NO — the same mechanics mirrored.

Does Polymarket charge a fee on winnings?

Polymarket applies a fee only on net winnings at resolution, historically 2%. There is no fee to open, modify or cancel an order, so the fee line in this calculator exists because many other platforms, and some Polymarket configurations, do deduct on profit. Enter 0 to model a fee-free outcome.

What ROI should I expect on a Polymarket trade?

ROI is mechanically tied to the entry price. Buying at 55¢ and winning returns roughly 81.8% on the stake, while buying at 90¢ returns about 11.1%. Lower-priced contracts offer higher ROI but win less often — the price already encodes that trade-off, which is why expected value, not ROI alone, decides whether a trade is good.

Polymarket Profit Calculator — YES/NO Payout & ROI

⚡ Quick Summary

What it does: Converts an entry price and stake into the exact number of shares, gross payout, net profit, loss and ROI for a Polymarket position.
Formula: Shares = Stake ÷ Price. Gross payout = Shares × $1. Net profit = Gross payout − Stake − Fee.
Key insight: Every winning share always redeems for exactly $1, so your ROI is determined almost entirely by the price you paid — not by the size of the event.
Bottom line: Cheap contracts pay enormously when they win and lose most of the time. Let the Expected Value calculator decide whether the trade is worth taking.

How Polymarket Payouts Actually Work

Polymarket is a binary contract market. Every share is a promise that pays exactly $1 if the event resolves in your favour and exactly $0 if it does not. There is no partial payout and no variable multiplier — the only variable is the price you paid to acquire the share.

That single design choice is what makes the arithmetic so clean. If you buy at 55¢, each share costs you 55 cents and eventually returns a dollar, a gain of 45 cents per share. If you buy at 90¢, each share returns only 10 cents of profit. The price is the market's probability estimate, and it simultaneously sets your payoff.

This is why ROI on a prediction market looks nothing like ROI on an equity. A 5% move in a stock is a 5% gain; a contract bought at 5¢ that resolves YES is a 1,900% gain. The intuitive reading — "cheap means good" — is exactly backwards, because the cheap price is the market telling you the outcome is unlikely.

The Payout Formulas

Shares = Stake ÷ Price Gross payout = Shares × $1.00 Fee = Gross profit × fee rate Net profit = Gross payout − Stake − Fee ROI on win = Net profit ÷ Stake Example — $100 on YES at 55¢: Shares = 100 ÷ 0.55 = 181.82 Gross payout = 181.82 × $1.00 = $181.82 Fee (2%) = $81.82 × 0.02 = $1.64 Net profit = $181.82 − $100 − $1.64 = $80.18 ROI = 80.2%

Note the fee line. Polymarket has historically charged only on net winnings at resolution, so a losing position incurs nothing beyond the stake itself. The calculator exposes the fee field because the rate has changed over time and because other venues deduct differently — set it to zero and the numbers reconcile exactly to the gross payout.

Entry Price Determines Everything

Entry price	Shares per $100	Gross payout	Net profit (no fee)	ROI	Break-even win rate
10¢	1,000.0	$1,000.00	+$900.00	900%	10%
25¢	400.0	$400.00	+$300.00	300%	25%
40¢	250.0	$250.00	+$150.00	150%	40%
55¢	181.8	$181.82	+$81.82	81.8%	55%
75¢	133.3	$133.33	+$33.33	33.3%	75%
90¢	111.1	$111.11	+$11.11	11.1%	90%

Read the last column carefully, because it is the entire risk story. A 10¢ contract only breaks even if you win more than 10% of the time. The market prices it at 10¢ because the crowd believes the real chance is about 10% — meaning the trade is a coin flip on whether your analysis is better than theirs. The headline ROI of 900% is not a reward for a safe bet; it is compensation for a genuinely unlikely outcome.

Conversely, a 90¢ contract wins nine times out of ten and returns 11.1%. Put $100 there ten times and a single loss wipes out the profit from the nine wins. Both structures can be profitable, but only if your probability estimate is measurably better than the price. That comparison is what expected value measures, and it is why the profit calculator is a feasibility check rather than a decision tool.

The NO Side, and Why It Is the Same Calculation

Buying NO is not a different kind of trade. It is buying the same contract at the complementary price. If YES trades at 55¢ then NO trades at 45¢, and the two prices sum to 100¢ — one dollar, exactly the payout. Buying $100 of NO at 45¢ gives about 222.2 shares, which redeem for $222.22 if the market resolves NO.

This symmetry has a practical consequence. There is no meaningful distinction between "betting against an event" and "buying the other side of it," which means the same sizing, the same expected value formula and the same risk limits apply. Beginners often treat NO as a hedge or as somehow safer. It is not. It is a straightforward directional position on the complementary outcome.

Worked Example: A Typical Polymarket Trade

Suppose a market asks whether a bill passes and YES trades at 68¢. You believe the true chance is 80% and decide to commit $250.

Shares: $250 ÷ 0.68 = 367.65 shares.
Gross payout if YES: 367.65 × $1.00 = $367.65.
Gross profit: $367.65 − $250 = $117.65.
Fee at 2% on winnings: $2.35.
Net profit: $115.30, which is a 46.1% ROI.
If the bill fails, the loss is the full $250.

Now weigh it. An 80% confidence against a 68% price implies a genuine edge, but it still means roughly one loss in five. Two losses in a row would cost $500 against $115 of profit per win — six winning trades to recover a single doubling of bad luck. That asymmetry is not a flaw in the calculation; it is the reason position sizing matters more than trade selection for long-term survival.

Where This Calculator Fits in a Workflow

Find a candidate market using on-chain flow or the mispricing scanners.
Form an independent probability estimate from primary sources.
Check the edge with the Expected Value Calculator — is your estimate above the implied probability by enough to clear costs?
Size the position with Kelly or a fractional variant.
Confirm the payout here: shares, gross return, net profit and the loss if you are wrong.
Record it so your calibration can be measured later.

Common Mistakes

Chasing high ROI. A 900% ROI at 10¢ needs a 10%+ win rate to break even. High ROI and high probability are opposites.
Ignoring the loss scenario. Every binary position loses 100% of its stake when wrong. The calculator shows this explicitly for a reason.
Forgetting fees on large repeated trades. Two percent of winnings compounds against a high-frequency strategy.
Confusing gross payout with profit. $181.82 returned on a $100 stake is $81.82 of profit, not $181.82.
Sizing by ROI instead of by edge. ROI is determined by price; only edge tells you whether the trade should exist at all.

Frequently Asked Questions

How many shares does $100 buy?

Divide the stake by the price. At 55¢ that is $100 ÷ 0.55 = 181.82 shares, each redeeming for $1 if correct.

Is buying NO safer than buying YES?

No. NO is the same contract at the complementary price. The risk profile is identical in structure.

What if my position loses?

You lose the full stake. There is no partial redemption and no salvage value on a binary contract.

Does this include slippage?

No. It assumes you fill at the stated price. On thinly traded markets your effective entry will be worse, which reduces both profit and ROI.

Polymarket Profit Calculator