KDEN uses Mountain Time: UTC−7 in winter and UTC−6 during daylight saving. See the exact Denver-to-UTC conversion, DST dates and rollover rule.
Denver International Airport (KDEN) uses Mountain Time: MST (UTC−7) in winter and MDT (UTC−6) during daylight saving time. In flight simulators and real-world aviation, convert KDEN local time to UTC by adding seven hours in MST or six in MDT, advancing the UTC date if the result passes midnight.
What is KDEN's UTC offset?
Denver, Colorado observes daylight saving time, so KDEN has two UTC offsets during the year. This applies in general flight simulation, including MSFS, FSX, X-Plane and Prepar3D.
| KDEN time | UTC offset | Local-to-UTC conversion |
|---|---|---|
| Mountain Standard Time (MST) | UTC−7 | Add 7 hours |
| Mountain Daylight Time (MDT) | UTC−6 | Add 6 hours |
UTC itself never changes for daylight saving time. The offset must therefore be chosen from the date at Denver, not from your computer's time zone or the departure airport's local time.
How do I convert Denver time to UTC or Zulu?
- Check the KDEN date. Determine whether Denver is observing MST or MDT on the date being simulated.
- Add the applicable offset. Add seven hours for MST or six hours for MDT.
- Correct the date. If the total reaches 24:00 or later, subtract 24 hours and move to the next UTC date.
- Write the result as UTC or Zulu. For example, 21:30 UTC may be written as
2130Z.
- 15 January at 14:30 MST becomes 21:30 UTC on 15 January.
- 15 July at 14:30 MDT becomes 20:30 UTC on 15 July.
- 15 January at 20:00 MST becomes 03:00 UTC on 16 January.
For the reverse calculation, subtract seven hours from UTC during MST or six during MDT, moving to the previous date where necessary. For routes involving several local zones, our guide to handling time zones in simulator flight planning explains why keeping the operational timeline in UTC prevents ETA errors.
When does Denver change between MST and MDT?
Under the US daylight-saving rule used for dates from 2007 onwards, Denver changes to MDT on the second Sunday in March and returns to MST on the first Sunday in November. In spring, the local clock jumps from 02:00 to 03:00; in autumn, the 01:00 hour occurs twice.
Do not assume every date labelled “summer” uses UTC−6. Flights close to a changeover need a date-aware time-zone setting. Historical recreations before 2007 may also require different US transition dates.
Why is KDEN one hour wrong in my flight simulator?
A one-hour discrepancy almost always means the simulator or an add-on has applied the wrong daylight-saving offset. Check the simulated date, confirm whether the displayed clock is labelled local or UTC, and make sure you have not manually added an offset after the simulator already converted it.
Another common mistake is reading a METAR timestamp as Denver local time. A timestamp ending in Z is already UTC, as explained in our guide to decoding METAR times and weather groups; it must not be converted to UTC again.
If the simulator clock still disagrees after checking MST versus MDT, use our simulator clock and time-zone troubleshooting steps to check UTC mode, local-time mode, the simulation date and computer-clock synchronisation.