How to make money on Polymarket: the mechanics, costs, and risks

It is possible to make money on a prediction market, and it is equally possible to lose the entire amount paid for an outcome that resolves to zero. In a simple binary market, a winning share is worth 1 at resolution and a losing share is worth 0. A trader can profit in two basic ways: hold a position bought below its winning payout through resolution, or sell it before resolution for more than its cost. Actual net profit must subtract applicable trading fees, bid-ask spread, slippage, transfer or funding costs, taxes, and any other costs relevant to the trader.

The difficult part is not the payout formula. It is finding a repeatable informational or pricing advantage after the market and costs have had their say. A high win rate alone does not prove profitability: buying many contracts at 0.95 can produce frequent wins and still lose money if losses occur more often than the price implies. Conversely, a lower win rate can be profitable when winners pay enough relative to entries. Judge decisions by expected value and risk-adjusted results across a meaningful sample, not screenshots of a single payout.

Access, product structure, fees, and geographic restrictions can change. Check Polymarket's current official materials and determine whether access is lawful and available where you are. Refract does not provide a route around venue or regional restrictions.

Suppose you buy 100 YES shares at an average price of 0.40. The position costs 40 before other costs. If YES resolves to 1, the resolution value is 100 and gross profit is 60. If YES resolves to 0, gross loss is 40. At a true 40% chance, the simplified expected resolution value equals the 40 cost, so expected profit before costs is zero. Because real trading has frictions and your probability estimate may be wrong, practical break-even is higher than 40%.

Expected value for a YES share held to a binary resolution can be written as p - c, where p is your probability of YES and c is all-in cost per share. If you estimate p = 0.47 and all-in cost = 0.41, estimated EV is +0.06. For 100 shares, that is +6 in expectation—not a promised 6. This trade still has a 53% estimated chance of losing its entry cost. Expected value describes an average across repeated comparable opportunities; the next result remains binary.

Prices can also move before resolution. Buying at 0.40 and selling at 0.55 creates a 0.15 gross gain per share, but only if there is a buyer for your size at that price. A chart or displayed midpoint is not proof of an available exit. If your sell order fills across 0.55, 0.53, and 0.50, calculate profit from the weighted average fill and subtract costs on both sides where applicable.

The all-in break-even price is not always the number printed beside BUY. Start with the weighted average fill, then include every applicable friction. Polymarket publishes a current trading-fee explanation and technical fee information in its documentation. Fee coverage, rates, calculation methods, incentives, and rebates are time-sensitive and may differ by product or market. This article deliberately does not freeze a rate that could become inaccurate; check the live order preview and official fee page at the time of a decision.

Spread

The gap between the best bid and offer. Crossing it to enter and again to exit can consume a small edge.

Slippage

The difference between an expected price and the average fill as an order uses available depth or the book moves.

Trading fees

Venue charges that may depend on current rules, market, side, price, or maker/taker status.

Funding and transfer costs

Potential wallet, bridge, network, conversion, deposit, or withdrawal costs and operational risk.

Capital and time

Money tied up until an uncertain resolution cannot be used elsewhere; delays reduce annualized returns.

Tax and recordkeeping

Obligations vary by jurisdiction and circumstances; obtain qualified advice rather than assuming.

A useful worksheet has separate fields for thesis price, limit price, expected average fill, worst acceptable fill, estimated fees, other direct costs, and error buffer. If the conservative forecast no longer clears the final break-even number, skip the trade. An edge that exists only when costs are ignored is not an economic edge.

Polymarket describes prices as the result of participant trading and documents an order-book model. Buyers post bids; sellers post offers; compatible orders match. The best visible offer may cover only a small number of shares. Therefore, “the market price was 62 cents” is incomplete. Was 0.62 the last trade, midpoint, best offer, or average price available for your full order?

Consider offers of 50 shares at 0.60, 100 at 0.64, and 350 at 0.69. A trader who sees 0.60 and submits an immediately executable 500-share buy would average 0.676 before fees. At resolution, the gross maximum gain if YES wins is 0.324 per share, while the loss if NO wins is 0.676. That payoff needs a much higher probability than the top quote suggests. Large orders in thin markets can manufacture their own bad entry.

A limit order says the worst price you accept. It may rest, fill partly, or never fill. This protects price, not outcome. A resting order can become stale just as better-informed traders arrive, which is adverse selection. An immediately executable order prioritizes certainty of execution, not price. Neither order type is universally superior.

• Inspect cumulative shares at each price level, not only the best quote.
• Calculate the volume-weighted average for the entire intended order.
• Set a price ceiling or floor from conservative value, then accept that no fill is possible.
• Plan partial fills: decide whether a smaller position still makes sense.
• Recheck resting orders after news and before periods when you cannot monitor them.
• Assume exit depth may be worse than entry depth, particularly around surprises.

Liquidity is not the same as reported volume. Historical volume says trading happened; current depth shows what might execute now, and even displayed liquidity can be canceled. Profit shown at a midpoint is not realized profit. Only an actual exit fill or settlement establishes the value you receive.

There are several economic routes to a positive result. Forecasting edge means your probability estimates are better calibrated than prices in a defined area. Speed and interpretation edge means you can verify and correctly map public information to contract language before it is fully reflected—but latency, false reports, and fast repricing make this hard. Liquidity provisionmeans patiently offering prices to others and earning a favorable spread or any applicable incentive, while accepting inventory and adverse-selection risk. Relative value means identifying inconsistent prices among logically related contracts, while respecting different deadlines and resolution wording.

None of these is “money from being right.” Forecasting skill can be overwhelmed by a bad price. Fast reaction can become expensive headline chasing. Liquidity providers can collect many small gains and then trade against someone with superior information. Related contracts may not be fungible, and a multi-leg position can become exposed when only one order fills. Rewards or rebates, if currently offered, should be modeled as variable program terms—not assumed permanent income.

Write a falsifiable explanation of the edge before entering. Then track results in two ledgers: forecast quality and execution quality. For forecasting, save the probability at decision time and later assess calibration. For execution, compare your average fill with the contemporaneous book and your limit. Profit and loss combine both, plus variance. A lucky win can hide a poor forecast; a well-reasoned positive-EV trade can lose. Process evidence emerges only over repeated, honestly recorded decisions.

The companion Polymarket strategies guide turns these sources of edge into a research, execution, and review playbook. Keep that strategy work separate from claims about whether any individual can earn a dependable income; the latter depends on skill, capital, opportunity set, costs, variance, and personal circumstances.

Start from the loss, not the hoped-for payout. For a long binary outcome held to resolution, the amount paid can fall to zero. Set the maximum tolerable loss per thesis before opening it. Then total all positions and resting orders exposed to the same event. Five political contracts may be one election bet; several economic releases may all depend on the same recession scenario. Names do not create diversification—different loss drivers do.

Model error is the main reason not to bet the maximum suggested by a precise formula. If you estimate 60% but the defensible range is 51–66%, sizing from 60 alone overstates confidence. Use the conservative end, impose hard portfolio caps, and reserve capacity for all open orders to fill together. Avoid martingale-style increases after losses: the next contract does not owe you a recovery, and a lower price may reflect genuinely worse information.

Drawdowns affect behavior as well as balances. A position small enough to evaluate calmly is more useful than one that forces reactive decisions. Diversification can reduce concentrated exposure, but as Investor.gov notes, it cannot guarantee against losses. If losing the full entry would affect essential expenses, the position is too large.

Before price analysis, read the full resolution criteria. Extract the subject, qualifying action, deadline and time zone, data source, required finality, exclusions, and what happens if the event is postponed or the source is unavailable. Review clarifications and understand the dispute path. Polymarket's official resolution overview should be treated as required background, while the specific market's rules govern that contract.

Wording risk is not merely legal fine print. “Announced,” “launched,” “available,” and “approved” can describe different observable events. Preliminary data can differ from final data. Local dates can differ from UTC. A person can effectively perform an action without satisfying the named source's formal classification. Price the written event, and skip contracts whose ambiguity you cannot bound.

Operational failures also matter: mistaken network or asset choices, compromised credentials, unavailable access, order-entry errors, stale open orders, and delayed resolution can change economics. Venue rules and regional eligibility may change. Verify current official information rather than relying on a tutorial's screenshots. Never share credentials or seed phrases, and do not treat a third party as venue support.

Begin with manual paper forecasts: select a narrow topic, record probability ranges before checking outcomes, and score calibration after enough events resolve. Next, add order-book simulation. Capture the bid, offer, cumulative depth, intended limit, hypothetical fill, estimated costs, and whether a real order would have filled. Do not award yourself the day's best price after seeing the chart.

Refract Funding offers another practice route using simulated balances, positions, orders, and fills. Refract is not affiliated with Polymarket, does not route orders to it, and does not guarantee that simulated performance will transfer to any live venue. Use the Polymarket paper-trading guide to build a journal, and read the program guide before relying on any Evaluation or funded-program assumption.

1. Choose one market category and write a base-rate forecast.
2. Parse the exact resolution test and list ambiguous cases.
3. Set a conservative probability range without anchoring on a desired payout.
4. Calculate weighted execution, spread, slippage, current fees, and an error buffer.
5. Size by maximum correlated loss and include every resting order.
6. Record the hypothetical order before news or outcome data arrives.
7. Review forecast calibration, fill quality, rule interpretation, and discipline separately.

Advance only when the journal is complete enough to reveal mistakes, not when a short run happens to be profitable. Compare simulated assumptions with current venue mechanics, legal availability, and personal risk tolerance. This material is educational, not investment advice. No strategy or hypothetical example guarantees a profit. Trading, balances, positions, and fills on Refract Funding are simulated. Refract Funding is independent of Kalshi and Polymarket. It uses their published market data as a simulation reference and does not send user orders to either venue.