Time Difference Calculator
Calculate time difference and meeting overlap between two cities or time zones worldwide.
Enter two cities or time zones to instantly see the live time difference in hours and minutes, the current local time in each location, business hours overlap window for meetings, and a real-time converter showing what any time in City A is in City B.
⏱ Time Difference Calculator
Select two cities to calculate the current time difference and find meeting overlap windows.
💼 Business Hours Overlap
Find the best meeting window for your team.
🔄 Meeting Time Converter
Pick a time in Location A to instantly see the equivalent in Location B.
🌍 Add More Locations
🗓️ World Reference — Current UTC Offsets (live)
| City | Local Time | UTC Offset | Abbr | DST | vs A |
|---|---|---|---|---|---|
| 🌺 Honolulu | Tue 1:17 AM | UTC-10:00 | HST | No | -6h |
| 🦅 Anchorage | Tue 3:17 AM | UTC-8:00 | AKDT | Yes | -4h |
| 🎬 Los Angeles | Tue 4:17 AM | UTC-7:00 | PDT | Yes | -3h |
| 🏔️ Denver | Tue 5:17 AM | UTC-6:00 | MDT | Yes | -2h |
| 🌮 Mexico City | Tue 5:17 AM | UTC-6:00 | CST | No | -2h |
| 🌆 Chicago | Tue 6:17 AM | UTC-5:00 | CDT | Yes | -1h |
| 🗽 New York | Tue 7:17 AM | UTC-4:00 | EDT | Yes | ±0h |
| 🍁 Toronto | Tue 7:17 AM | UTC-4:00 | EDT | Yes | ±0h |
| 🇧🇷 São Paulo | Tue 8:17 AM | UTC-3:00 | GMT-3 | No | +1h |
| 🇦🇷 Buenos Aires | Tue 8:17 AM | UTC-3:00 | GMT-3 | No | +1h |
| 🎡 London | Tue 12:17 PM | UTC+1:00 | GMT+1 | Yes | +5h |
| 🇵🇹 Lisbon | Tue 12:17 PM | UTC+1:00 | GMT+1 | Yes | +5h |
| 🗼 Paris | Tue 1:17 PM | UTC+2:00 | GMT+2 | Yes | +6h |
| 🇩🇪 Berlin | Tue 1:17 PM | UTC+2:00 | GMT+2 | Yes | +6h |
| 🏛️ Rome | Tue 1:17 PM | UTC+2:00 | GMT+2 | Yes | +6h |
| 🐪 Cairo | Tue 2:17 PM | UTC+3:00 | GMT+3 | Yes | +7h |
| 🕌 Istanbul | Tue 2:17 PM | UTC+3:00 | GMT+3 | No | +7h |
| 🦅 Moscow | Tue 2:17 PM | UTC+3:00 | GMT+3 | No | +7h |
| 🏙️ Dubai | Tue 3:17 PM | UTC+4:00 | GMT+4 | No | +8h |
| 🇵🇰 Karachi | Tue 4:17 PM | UTC+5:00 | GMT+5 | No | +9h |
| 🌶️ Mumbai | Tue 4:47 PM | UTC+5:30 | GMT+5:30 | No | +9h 30m |
| 🇮🇳 New Delhi | Tue 4:47 PM | UTC+5:30 | GMT+5:30 | No | +9h 30m |
| 🇧🇩 Dhaka | Tue 5:17 PM | UTC+6:00 | GMT+6 | No | +10h |
| 🛺 Bangkok | Tue 6:17 PM | UTC+7:00 | GMT+7 | No | +11h |
| 🦁 Singapore | Tue 7:17 PM | UTC+8:00 | GMT+8 | No | +12h |
| 🐉 Beijing | Tue 7:17 PM | UTC+8:00 | GMT+8 | No | +12h |
| 🏙️ Hong Kong | Tue 7:17 PM | UTC+8:00 | GMT+8 | No | +12h |
| ⛩️ Tokyo | Tue 8:17 PM | UTC+9:00 | GMT+9 | No | +13h |
| 🇰🇷 Seoul | Tue 8:17 PM | UTC+9:00 | GMT+9 | No | +13h |
| 🦘 Sydney | Tue 9:17 PM | UTC+10:00 | GMT+10 | No | +14h |
| 🥝 Auckland | Tue 11:17 PM | UTC+12:00 | GMT+12 | No | +16h |
Click any row to set it as Location B.
Time Difference Technical Specifications & Standards
IANA Time Zone Database (TZDB). UTC offsets and DST transitions are computed using browser-native Intl.DateTimeFormat APIs
Standard global ellipsoidal coordinate reference system
UTC-Based Geodesics
UTC offsets are accurate to the minute. The tool reflects the real DST status at the moment of the calculation — it does not rely on static offset tables. Offsets can change during DST transitions twice per year.
GeoJSON · KML · CSV · SVG
Compatible with QGIS, ArcGIS, Google Earth & CAD
100% Client-Side
Calculations run in-browser. Zero coordinate logging.
How to Use the Time Difference Calculator
Follow this step-by-step procedure to execute precise spatial measurements and export results.
- 1Select two locations: Choose Location A and Location B from the preset city dropdowns, or click "Search any city…" to geocode any address, city name, or landmark in the world.
- 2Read the live time difference: The result hero displays the live time difference (e.g. "+5h") and both current local times, which update every second. The difference accounts for DST — it reflects the real offset right now, not a fixed value.
- 3Find your business hours overlap: The Business Hours Overlap panel shows exactly how many hours of working time the two locations share and the best window for scheduling calls. Choose from four work-hours presets or adjust later.
- 4Convert a specific meeting time: Use the Meeting Time Converter to pick any time in Location A (e.g. 10:00 AM) and instantly see what that time is in Location B, including a "next day" alert if the conversion crosses midnight.
- 5Add more cities: Click "Add City" or use the quick-add preset chips to add a third, fourth, or more locations to a live world-time dashboard. Remove any city with the × button.
- 6Click the world reference table: Click any row in the 30-city reference table to instantly set that city as Location B, letting you quickly scan the time difference against any major world hub.
Geodesic Precision vs. Competitor Mapping Approaches
Most legacy mapping utilities (such as CalcMaps and FreeMapTools) rely on planar Web Mercator projections or spherical approximations, causing significant mathematical distortion at higher latitudes. GeoMap Suite computes exact ellipsoidal geodesics on the WGS84 reference ellipsoid.
| Calculation Model | Mathematical Basis | Distortion on WGS84 | Standard Tools | Practical Application |
|---|---|---|---|---|
| Planar (Web Mercator) | Cartesian dx² + dy² | 10% to 200%+ error | CalcMaps / Simple map tools | Distorts drastically away from equator. Inaccurate for true distance. |
| Spherical Great-Circle | Haversine (R = 6,371 km) | Up to 0.5% (~5 km/1,000 km) | Basic Google Maps wrappers | Ignores Earth's polar flattening. Reasonable for rough estimates. |
| GeoMap Suite Ellipsoidal | Karney Direct/Inverse WGS84 | < 15 nanometers (<0.0001%) | GeoMap Suite | Geodetic surveying, maritime, flight paths & legal boundary analysis. |
New York ↔ London meeting overlap
A US startup (New York) needs to schedule a weekly call with a London partner. They want to know the best time that works for both.
Input Parameters
- Location A
- New York, USA (America/New_York)
- Location B
- London, UK (Europe/London)
- Working hours
- Standard (9 AM–5 PM)
Computed Outputs
- Time Difference
- +5 hours (summer) or +5 hours (winter)
- Overlap Duration
- 3 hours
- Best Call Window
- 9–12 AM New York / 2–5 PM London
Step-by-Step Mathematical Process
- Select "New York, USA" as Location A and "London, UK" as Location B.
- In summer (EDT vs BST): New York is UTC-4, London is UTC+1 → difference = +5h.
- Business hours for New York in UTC: 13:00–21:00.
- Business hours for London in UTC: 08:00–16:00.
- Overlap in UTC: 13:00–16:00 (3 hours).
- In New York local time: 9 AM–12 PM. In London local time: 2 PM–5 PM.
Los Angeles ↔ Tokyo meeting planner
A California engineering team needs to sync with their Tokyo office. They want to know if any overlap exists.
Input Parameters
- Location A
- Los Angeles, USA (America/Los_Angeles)
- Location B
- Tokyo, Japan (Asia/Tokyo)
- Working hours
- Standard (9 AM–5 PM)
Computed Outputs
- Time Difference
- +17h (winter PST/JST)
- Overlap (9–5)
- No overlap
- Workaround
- 8 AM LA = 1 AM Tokyo; 5 PM LA = 10 AM next day Tokyo
Step-by-Step Mathematical Process
- Select Los Angeles and Tokyo.
- PST (winter): UTC-8. JST: UTC+9. Difference = +17h.
- LA business hours in UTC: 17:00–01:00 (next day).
- Tokyo business hours in UTC: 00:00–08:00.
- Overlap in UTC: 00:00–01:00 (1 hour) — only for extended hours preset.
- For standard 9–5: 5 PM in LA = 10 AM next day in Tokyo → no overlap.
Convert 3 PM EST to Singapore time
A contract lawyer in New York signs a document at 3:00 PM EST. The Singapore counterpart needs to know the equivalent Singapore Standard Time for filing records.
Input Parameters
- From
- 3:00 PM Eastern Standard Time (America/New_York, winter)
- To
- Asia/Singapore (UTC+8)
Computed Outputs
- Input Time
- 3:00 PM EST (UTC-5)
- Output Time
- 4:00 AM SGT (UTC+8) — next day
- UTC
- 20:00 UTC
Step-by-Step Mathematical Process
- Set Location A to New York, Location B to Singapore.
- Select 3:00 PM in the Meeting Time Converter.
- EST (winter) is UTC-5; Singapore is UTC+8.
- 3:00 PM EST = 20:00 UTC.
- 20:00 UTC + 8h = 04:00 next day Singapore time.
Understanding Your Results & Practical Interpretation
Time Difference (hours and minutes)
The signed difference in UTC offsets between the two selected locations at this exact moment. A positive value means Location B is ahead of Location A (further east). The value accounts for DST — if one location observes summer time and the other does not, the difference changes at the DST transition date.
Business Hours Overlap
The overlap window is calculated by projecting both zones' working hours (default 9 AM–5 PM) onto the UTC timeline and finding their intersection. The result is displayed in each zone's local time so both parties can immediately see the window on their own clock.
Meeting Time Conversion
A specific local time in Location A is converted to UTC (subtract offset A), then the target offset B is added to yield the equivalent wall-clock time in Location B. A "next day" badge appears when the conversion crosses midnight.
DST Active badge
Shown when Daylight Saving Time is currently in effect for that location. DST typically advances the clock by 1 hour, increasing the UTC offset by 60 minutes. The time difference between two locations may therefore be different in summer vs winter if they follow different DST schedules.
Practical Applications & Real-World Use Cases
Remote Team Scheduling
Find the exact overlap window between distributed team members across multiple continents to schedule stand-ups, retrospectives, and 1:1s during everyone's working hours.
Client Communication
Before calling an international client, verify what time it is there right now and confirm they are within business hours — avoiding calls at 3 AM.
Global Event Broadcasting
Convert a planned broadcast time to every major region's local time to publish accurate schedules for Asia-Pacific, Europe, and Americas audiences simultaneously.
Contract & Legal Deadlines
Convert deadline times across jurisdictions — e.g. convert a New York Stock Exchange 4 PM ET close to the equivalent time in Tokyo, Frankfurt, and Sydney for trade settlement.
Travel Planning
Before a long-haul flight, calculate how many hours ahead or behind the destination is and plan sleep, meals, and medication schedules to minimise jet lag.
Software Deployment Coordination
Schedule deployments during the joint off-peak window for all regions to minimise user impact during maintenance windows.
Mathematical Methodology & Geodetic Accuracy
UTC-Based Offset Arithmetic
Time zone conversion works by converting both local times to UTC, then adding the target UTC offset. The business-hours overlap window is found by intersecting the two zones' 9–5 windows projected onto the UTC timeline.
T_B = T_A − UTC_A + UTC_BLimitations & Boundary Conditions
- •DST rules are set by government decree and can change with short notice. The browser's TZDB may lag behind very recent changes until the next browser update.
- •The business hours overlap assumes standard working hours are defined identically in both cities. Public holidays and non-standard company hours are not considered.
- •The Meeting Time Converter does not account for calendar day boundaries beyond a ±24h window.
- •Searching by city name requires a network connection (Photon geocoding API) and coordinate-to-timezone resolution (Open-Meteo API).
Troubleshooting & Geographic Edge Cases
The time difference changed — why is it different now than last month?
One or both zones switched to/from Daylight Saving Time. DST transitions happen twice a year and change the UTC offset by ±60 minutes. For example, New York–London is +5h in summer (EDT vs BST) and also +5h in winter (EST vs GMT), but New York–Los Angeles is always -3h because both cities observe US DST on the same schedule.
My search returns a wrong city — what should I do?
The search uses the Photon geocoding API (OpenStreetMap data). Try adding the country or state to disambiguate — e.g. "Springfield, Illinois" instead of "Springfield". The tool then resolves the IANA time zone from the returned coordinates via Open-Meteo.
No business hours overlap is shown even though I expected some.
The default working hours preset is 9 AM–5 PM. For zones with very large differences (e.g. Los Angeles and Tokyo at 17h apart), no standard 8-hour window overlaps. Try the "Extended (8–6)" preset to get 1 additional hour on each end, or consider planning asynchronous communication.
The meeting converter shows "next day" — is that correct?
Yes. If Location B is many hours ahead of Location A, an afternoon meeting in A can fall in the early morning hours of the following calendar day in B. The "next day" badge is a reminder that the date changes — participants in B may need to note the meeting on the following day's calendar.
Why does China show UTC+8 even though it spans five geographic time zones?
China adopted a single national time zone (China Standard Time, UTC+8, IANA: Asia/Shanghai) in 1949. Geographically the western regions of China are closer to UTC+5 or UTC+6 solar time, but the government mandates UTC+8 nationwide for administrative simplicity.
Frequently Asked Questions
Not necessarily. If both locations observe DST on the same schedule (e.g. both are US cities), the difference stays constant year-round. If only one location observes DST, or they transition on different dates (US vs EU clocks change on different weeks), the difference shifts by 1 hour for a few weeks each spring and autumn.