A new decision-making tool is available for Wisconsin corn farmers and professional consultants to estimate the expected net benefit from Bt corn for controlling European corn borer (ECB). Bt corn provides essentially complete control of the ECB, but corn borer pressure each year is uncertain. The tool uses Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) pest survey data to estimate typical ECB populations for each crop reporting district and the associated yield loss. The tool predicts the expected net return from planting Bt corn and the break-even probability. The expected net return is the increase in expected (average) returns net of the additional cost for Bt corn. The break-even probability is the probability that the value of the yield saved by planting Bt corn will equal or exceed the additional cost for Bt corn. Most importantly, the tool uses the farmer’s yields and prices, so the expected net benefit and break-even probability are specific to the farmer’s operation.