Kalshi & Polymarket Profit Calculator
Estimate your actual take-home after platform fees and taxes. See what you keep, not just what you gross.
Results
Gross Profit
$60.00
$40.00 invested
Platform Fees
−$2.00
$0.02/contract × 100
Estimated Tax
−$13.92
24% on $58.00
Net Take-Home
$44.08
+110.2% ROI after fees & taxes
| Line Item | Amount |
|---|---|
| Total Invested | $40.00 |
| Gross Profit (+60¢ × 100) | +$60.00 |
| Platform Fees (Kalshi taker) | −$2.00 |
| Estimated Tax (24%) | −$13.92 |
| Net Take-Home | $44.08 |
Tax estimate assumes short-term capital gains treatment. This is not tax advice - consult a CPA.
What does this calculator do?
The net profit calculator estimates what you actually take home from a prediction market trade after accounting for platform fees and applicable taxes. Gross payout is what the contract pays on resolution. Net profit is what lands in your pocket. The gap between those two numbers is larger than most traders expect, especially on PredictIt where a profit fee and withdrawal fee compound on top of each other.
Enter your stake, contract price, and the platform you're trading on. The calculator applies the relevant fee structure — Kalshi's per-contract transaction fees, PredictIt's 10%-of-profit fee plus optional 5% withdrawal fee, or Polymarket's category-based fee curve — and then applies your marginal tax rate to the net gain to show your true after-tax take-home. Different tax jurisdictions treat prediction market gains differently; consult a tax professional for your specific situation.
This matters most for position sizing decisions. If you're allocating $500 to a 0.70 contract and expecting to profit $214 gross, your actual net after a 24% federal rate and PredictIt fees might be closer to $140. That changes your effective return and therefore how much capital it makes sense to deploy relative to your alternatives.
Use this alongside the Expected Value calculator to understand both your edge and your actual realized return. A trade with positive EV can still be unattractive after fees and taxes if the net return doesn't justify the capital at risk. The Market Fees calculator gives you a more granular breakdown of platform costs at any contract price.