diff --git a/README.md b/README.md
index fae1c31..cb5e551 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
-
 # Someday
 
 **Free to host calendar availability picker - open-source cal.com / calendly alternative built on [Google-Apps-Script](https://developers.google.com/apps-script) for Gmail users.**
@@ -112,6 +111,17 @@ __you may need to sign out of all accounts, and only into your target account__
    - Authorization modal will pop up, 'Review permissions', select your account, you will see a warning, go to advanced, then Go to <your script>(unsafe) then click Allow
    - if it worked, refresh the page/editor then run the function again and it should complete without issue.
 
+5. **Calendar Access:**
+   - By default, the script uses your primary calendar
+   - To use other calendars, make sure they are added to your Google Calendar with appropriate permissions
+   - You can change which calendar to use by modifying the `CALENDAR` variable in `backend/src/app.ts`
+   - Note: The script needs at least read access to the calendar you specify
+   - To use multiple calendars, you'll need to add them as Script Properties in the Apps Script editor:
+     1. Open the script editor with `clasp open`
+     2. Go to Project Settings (⚙️ icon)
+     3. Under "Script Properties", click "Add Script Property"
+     4. Add a property named "CALENDARS" with a comma-separated list of calendar IDs
+
 ## Cheat Sheet
 
 - `npm run deploy` - build and delpoy
diff --git a/backend/src/app.ts b/backend/src/app.ts
index a6cd5f1..470428d 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -1,5 +1,15 @@
-const CALENDAR = "primary";
-const TIME_ZONE = "America/New_York";
+const CALENDARS: string[] = (() => {
+  const calendarsProp = PropertiesService.getScriptProperties().getProperty('CALENDARS');
+  try {
+    if (!calendarsProp) return ["primary"];
+    const parsed = JSON.parse(calendarsProp);
+    return Array.isArray(parsed) ? parsed : ["primary"];
+  } catch (e) {
+    Logger.log(`Error parsing CALENDARS property: ${e}`);
+    return ["primary"];
+  }
+})();
+const TIME_ZONE = "America/Los_Angeles";
 //  America/Los_Angeles
 //  America/Denver
 //  America/Chicago
@@ -8,7 +18,7 @@ const TIME_ZONE = "America/New_York";
 const WORKDAYS = [1, 2, 3, 4, 5];
 const WORKHOURS = {
   start: 9,
-  end: 13,
+  end: 16,
 };
 const DAYS_IN_ADVANCE = 28;
 //high numbered days in advance cause significant loading time slow down
@@ -29,7 +39,6 @@ function fetchAvailability(): {
   const nearestTimeslot = new Date(
     Math.floor(new Date().getTime() / TSDURMS) * TSDURMS
   );
-  const calendarId = CALENDAR;
   const now = nearestTimeslot;
   const end = new Date(
     Date.UTC(
@@ -42,15 +51,18 @@ function fetchAvailability(): {
   const response = Calendar.Freebusy!.query({
     timeMin: now.toISOString(),
     timeMax: end.toISOString(),
-    items: [{ id: calendarId }],
+    items: CALENDARS.map((id: string) => ({ id })),
   });
 
-  const events = (
-    (response as any).calendars[calendarId].busy as {
-      start: string;
-      end: string;
-    }[]
-  ).map(({ start, end }) => ({ start: new Date(start), end: new Date(end) }));
+  const events = CALENDARS.map((calendarId: string) => {
+    const busyTimes = (response as any).calendars[calendarId].busy;
+    Logger.log(`Busy times for ${calendarId}: ${JSON.stringify(busyTimes)}`);
+    return busyTimes.map(({ start, end }: { start: string; end: string }) => ({ 
+      start: new Date(start), 
+      end: new Date(end) 
+    }));
+  }).reduce((acc, curr) => acc.concat(curr), []);
+
   //get all timeslots between now and end date
   const timeslots = [];
   for (
@@ -66,7 +78,7 @@ function fetchAvailability(): {
     if (startTZ.getHours() < WORKHOURS.start) continue;
     if (startTZ.getHours() >= WORKHOURS.end) continue;
     if (WORKDAYS.indexOf(startTZ.getDay()) < 0) continue;
-    if (events.some((event) => event.start < end && event.end > start)) {
+    if (events.some((event: { start: Date; end: Date }) => event.start < end && event.end > start)) {
       continue;
     }
     timeslots.push(start.toISOString());
@@ -81,8 +93,7 @@ function bookTimeslot(
   phone: string,
   note: string
 ): string {
-  Logger.log(`Booking timeslot: ${timeslot} for ${name}`);
-  const calendarId = CALENDAR;
+  const calendarId = CALENDARS[0];
   const startTime = new Date(timeslot);
   if (isNaN(startTime.getTime())) {
     throw new Error("Invalid start time");
@@ -90,24 +101,18 @@ function bookTimeslot(
   const endTime = new Date(startTime.getTime());
   endTime.setUTCMinutes(startTime.getUTCMinutes() + TIMESLOT_DURATION);
 
-  Logger.log(`Timeslot start: ${startTime}, end: ${endTime}`);
-
   try {
     const possibleEvents = Calendar.Freebusy!.query({
       timeMin: startTime.toISOString(),
       timeMax: endTime.toISOString(),
-      items: [{ id: calendarId }],
+      items: CALENDARS.map((id: string) => ({ id })),
     });
 
-    const busy = (possibleEvents as any).calendars[calendarId].busy;
+    const hasConflict = CALENDARS.some((calId: string) => 
+      (possibleEvents as any).calendars[calId].busy.length > 0
+    );
 
-    if (
-      busy.some((event: { start: Date; end: Date }) => {
-        const eventStart = new Date(event.start.toString());
-        const eventEnd = new Date(event.end.toString());
-        return eventStart <= endTime && eventEnd >= startTime;
-      })
-    ) {
+    if (hasConflict) {
       throw new Error("Timeslot not available");
     }
 
@@ -122,11 +127,9 @@ function bookTimeslot(
         status: "confirmed",
       }
     );
-    Logger.log(`Event created: ${event.getId()}`);
     return `Timeslot booked successfully`;
   } catch (e) {
     const error = e as Error;
-    Logger.log(`Failed to create event: ${error.message}`);
     throw new Error(`Failed to create event: ${error.message}`);
   }
 }