Below is a list of Janesville IL zip codes. For your research we have also included Janesville Area Code, Time Zone, UTC and the local Cumberland County FIPS Code. Each Janesville Illinois zip code has a center Longitude / Latitude point (the Janesville center is -88.248596191406 / 39.367599487305). For your convenience we have also indicated if that zip code in Janesville observes Daylight Savings time.