Contract calculator
What a prediction-market contract really costs: implied probability, payout, and the fee drag at the platform's own fee schedule.
How this model works: a contract that wins pays $1. The price is the market's implied probability before fees — a 50-cent contract implies 50%. Total cost is the position cost (contracts × price) plus the fee drag (contracts × fee per contract). The breakeven win rate is the total cost per contract: the win rate at which the position pays for itself. Effective hold is the fee drag as a share of your total cost.
Fee schedules on file are in the menu above, each with its source and the date it was checked. Every other platform is manual entry. Kalshi is modeled on its general taker schedule (0.07 × price × (1 − price) per contract, series multiplier 1); that schedule also sets maker fees and per-series multipliers, which this tool does not model.
Outputs are a model computed from the figures entered — not a quote, and not a prediction that a contract wins. Fees change; check the platform's current schedule before trading. The pick'em equivalent is the house edge index.
Fee schedules on file
| Platform | Fee | Source |
|---|---|---|
| $0.01 commission per contract plus a $0.01 exchange fee per contract; winning contracts settle at $1 | Plus500's own support page, as recorded in plus500-rolr-evaluation-2026-10-26.md (operator evaluation on file) (checked 2026-10-26) | |
| $0.025 per contract bought or sold, charged only on matched orders | ROLR's own fee schedule, as recorded in plus500-rolr-evaluation-2026-10-26.md and the ROLR evaluation note (operator evaluation on file) (checked 2026-10-26) | |
| General taker schedule: fees = 0.07 x contracts x price x (1 - price), price in dollars, series multiplier 1. Maker fees and per-series multipliers exist in the same schedule; this tool models the general taker schedule only. No settlement or membership fee. | Kalshi fee schedule (official PDF), 'Fee Schedule for July 2026', last updated and effective 2026-07-07 (checked 2026-11-03) |
A platform is listed only when its fee is stated in a cited source. Nothing here is estimated or filled in.