Free calculator
What Time Should I Leave?
Know exactly when to leave so you're not late.
Enter your destination, arrival time, and buffer. This departure time calculator uses real travel time and traffic to determine the exact moment to walk out the door.
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What time should I leave?
Start with your required arrival time, subtract travel time, then subtract a buffer for traffic or delays. The departure time calculator below does this automatically using real traffic data for your specific route and departure window.
Your leave time will appear here
Fill in your destination and arrival time.
Destination
Starting location (optional)
Arrival date
Arrival time
Travel mode
Extra buffer you like to have
Parking / walk-in time (optional)
Add a destination & time to enable.
Stop doing this math every time
OnTimer connects to your calendar and automatically figures out your departure time for meetings, appointments, and any event with a location. It alerts you at the right moment based on traffic, not a guess.
- ✓Time-to-Leave alerts based on real travel time and live traffic
- ✓Connects to Google Calendar and Microsoft Outlook
- ✓Works for any event with a location in your calendar
- ✓Stronger alerts that are harder to ignore than standard reminders
How this calculator works
The departure time calculation starts from your required arrival time, then subtracts travel time, your buffer, and any extra time for parking or check-in. The result is your exact leave time: when you should walk out the door.
Travel time is estimated using Google's Routes API, which accounts for current and predicted traffic based on your departure time. Walking and transit times are also supported. If Google cannot estimate the route, you can enter the travel time manually.
The buffer is there because real life is not perfectly predictable. A 10-minute buffer costs you very little if everything goes smoothly, but saves you a lot of stress if something small goes wrong.
What to factor in before you leave
Traffic is the most variable factor. A route that takes 20 minutes at 10 AM might take 40 minutes at 5 PM on the same road. If your meeting is during peak hours, use a realistic estimate: not the best-case time from an earlier route check.
Parking and getting inside takes longer than most people expect. Finding a spot, walking to the building, waiting for an elevator: these steps easily add 5 to 15 minutes before you are actually in the room. The prep time field in the calculator is for exactly this.
Give yourself a buffer even when you think you do not need one. Unexpected things happen: a slow traffic light, a confusing entrance, a detour. A 10-minute buffer costs almost nothing when everything goes right, and buys you meaningful peace of mind when it does not.
Why standard reminders often are not enough
Calendar reminders are easy to set and easy to dismiss. Most people set them for 15 or 30 minutes before an event, but that is often not enough time to actually get ready, get out the door, and drive somewhere with any margin.
Standard reminders also do not account for travel time at all. A 15-minute reminder before a meeting 25 minutes away means you are already late before you leave.
But there is a deeper problem. Even when the math is right, knowing when to leave and actually leaving are two different things. This is the Last 5 Minutes Problem: the execution gap between receiving a reminder and acting on it before the window closes. A passive notification that disappears does not close that gap. Persistent alarms do.
OnTimer works differently. It calculates your departure time based on real travel time and traffic, then fires a persistent alarm at the right moment — an alert that stays on your screen until you dismiss it, not a notification that vanishes.
What Time Should I Leave for Work?
Your commute takes longer during morning rush than a midday route check suggests. A drive that shows 20 minutes on Google Maps at noon can take 35 minutes when you are actually leaving at 8 AM. Your departure time calculation should use your actual departure window, not an off-peak estimate.
The formula: take your required arrival time, subtract your commute time at that hour, then subtract 5 to 10 minutes of buffer for minor delays. If you need to be at your desk by 9 AM and your rush-hour commute takes 28 minutes, your target departure time is 8:22 AM at the latest. Add time for parking or a longer building walk if needed.
Most commuters underestimate their departure time by 10 to 15 minutes because they plan based on best-case traffic. Rush hour adds time in both directions: the drive itself and the time to exit your neighborhood or reach the main route.
Use the departure time calculator above with your office address and your actual planned departure window. It returns a traffic-adjusted travel time estimate so you know your real leave-by time, not an optimistic one.
What Time Should I Leave for an Appointment?
For medical visits, dentist appointments, government offices, and any appointment with a hard start time, being late often means losing your slot. The buffer needed for arrival planning is higher than a typical commute.
Work backward from your appointment time. Subtract your travel time, add 10 to 15 minutes for check-in or registration, and include time for parking at an unfamiliar location. For appointments you cannot easily reschedule, a 15-minute cushion is worth building in.
The common mistake is treating the waiting room as your buffer. Receptionists mark you as late when you walk in, not when you sit down. Arriving at 2:03 for a 2:00 PM appointment means you were late.
Use the leave-time calculator above with your appointment address and required arrival time. Set the prep time field to include check-in time so your departure time accounts for the full picture.
What Time Should I Leave for a Meeting?
Whether you are meeting a client, heading to an off-site team meeting, or showing up for an interview, arriving on time signals that you planned ahead. Five minutes early is much better than two minutes late.
Work backward from the meeting start time. Subtract travel time, then add buffer for parking and finding the right floor or conference room. For an unfamiliar location, add extra time since navigating a new building takes longer than you expect.
For client meetings or interviews, plan to arrive 10 to 15 minutes before the meeting time. For internal team meetings at a familiar location, 5 minutes is usually enough.
The biggest variable is traffic at your specific departure time. A downtown meeting at 10 AM has different traffic conditions than the same route at 8:30 AM. Enter the meeting address and required arrival time into the departure time calculator above to get a traffic-adjusted leave time for your specific route and departure window.
What Time Should I Leave to Arrive On Time?
The formula for arrival planning is straightforward: departure time equals arrival time minus travel time minus buffer. The challenge is using the right inputs.
Traffic is the largest variable. Travel time at 7:30 AM differs from 9 AM, which differs from noon. Standard route checkers give you a current snapshot, but departure planning requires a traffic-adjusted estimate for the specific window you are targeting. The calculator on this page uses Google's Routes API to account for predicted traffic at your planned departure time.
The buffer matters more than people expect. A 10-minute buffer handles most common delays: a slow traffic light, a car looking for parking ahead of you, a longer walk from the parking structure. You almost never regret a buffer. You frequently regret not having one.
Departure timing is harder than it looks because small delays compound quickly. Most people who run late did not plan to cut it close. They just ran through the math too optimistically. Build the buffer in at the start and arrival planning becomes much more reliable.
Frequently asked questions
How do I calculate what time I should leave?+
Work backwards from when you need to arrive. Subtract your travel time, then subtract any buffer for unexpected delays, and any extra time you need for parking or checking in. The result is the latest you should walk out the door.
How much buffer should I add before a meeting or appointment?+
A 10-minute buffer handles most minor delays: a slow traffic light, a parking spot that takes a minute to find, or a brief wait in a lobby. For important appointments like job interviews or medical visits, 15–20 minutes is worth it.
Does travel time change based on when I leave?+
Yes. Traffic varies significantly by time of day and day of week. Leaving at 8 AM on a Tuesday is very different from leaving at 10 AM or on a Saturday. This calculator uses Google's live traffic data to estimate travel time based on when you plan to arrive.
What if I am taking transit or walking?+
Use the Transit or Walking mode in the calculator. Walking time is straightforward. Transit times depend on schedules and may have more variability, so adding a few extra minutes of buffer is a good idea.
What time should I leave for work?+
Calculate your commute time for the hour you would actually be leaving, not an off-peak estimate. Subtract that travel time from your required arrival time, then add 5 to 10 minutes of buffer. If your commute takes 30 minutes during morning rush and you need to arrive by 9 AM, your departure time should be no later than 8:20 AM. Use the calculator above with your specific route and departure window to get a traffic-adjusted estimate.
What time should I leave for a meeting or appointment?+
Back-calculate from the meeting or appointment start time. Subtract travel time, then add buffer for parking, check-in, or navigating a new building. For important appointments, a 10 to 15 minute buffer is a reasonable target. For client meetings or job interviews, plan to arrive at least 10 minutes early. Enter the address and arrival time into the calculator to get a specific departure time.
Can OnTimer automatically remind me when to leave?+
Yes. For any calendar event with a location, OnTimer calculates when you need to leave based on travel time and traffic, then sends you an alert at the right time. No manual calculation needed.
Related timing tools
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- Airport Time-to-Leave Calculator →
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- Time-to-Leave Reminders: Automatic Departure Alerts →
- How to Never Be Late to Meetings →
- ADHD Time Blindness: Tools That Actually Help →
- The Last 5 Minutes Problem: Why Reminders Fail When You Need Them Most →
- Turn Calendar Events Into Persistent Alarms →
Get there on time, every time
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