diff --git a/web/controllers/contracttab_controller.go b/web/controllers/contracttab_controller.go
index 75db8ac..1e2d960 100644
--- a/web/controllers/contracttab_controller.go
+++ b/web/controllers/contracttab_controller.go
@@ -59,7 +59,7 @@ func InsertContracttab(ctx iris.Context) {
 			supports.Error(ctx, iris.StatusBadRequest, err.Error(), nil)
 			return
 		}
-		days := (end.Unix() - start.Unix()) / 86400
+		days := (end.Unix() - start.Unix()) / (86400*30)
 		fmt.Println("days:", days)
 		lengthdate = float64(days)
 	case 2: