Chicago is typically 7 hours behind Paris. When it's 4:00 PM in Paris, it's 9:00 AM in Chicago. Both cities observe daylight saving time, though the transition dates differ slightly.
During the brief periods when the US and Europe change clocks on different weekends (usually in March and November), the difference can temporarily be 6 or 8 hours. For most of the year, it's a consistent 7-hour difference.
Optimal meeting window: 7:00 AM - 10:00 AM Chicago time (2:00 PM - 5:00 PM Paris). This catches afternoon business hours in Paris while being morning in Chicago.
Chicago's major corporations with European operations frequently schedule calls during this window.