Zulu to IRDT Time Converter

Convert Zulu (UTC+00:00) to IRDT (UTC+04:30) instantly.

Convert Zulu Time to IRDT

Convert Zulu (UTC+00:00) to IRDT (UTC+04:30) instantly.

Input Base Time

Target Timezone

Local Result

12:00 AM GMT+3:30

Live Visualization

Live Global Clock

Syncing

Current Zulu Time

12 3 6 9

16:27:05

May 25, 2026 UTC +00:00

Timezone intelligence

Zulu to IRDT Timezone Map

Visual UTC offset relationship, day and night split, and live timezone context for Zulu and IRDT.

UTC gap: +3h 30m

Iran Daylight Time (IRDT) is 3 hours 30 minutes ahead of Zulu Time (UTC) (Zulu)

Updated: 16:27Z

Zulu 16:27 UTC

GMT+3:30 19:57 GMT+3:30

Difference +3h 30m ahead

Source

Zulu Time (UTC) (Zulu)

UTC+00:00 | UTC

16:27 UTC

Target

Iran Daylight Time (IRDT)

UTC+03:30 | GMT+3:30

19:57 GMT+3:30

Relationship

Iran Daylight Time (IRDT) is ahead of Zulu Time (UTC) (Zulu)

Ahead/behind delta: +3h 30m

DST: Standard (GMT+3:30)

Offset band

UTC+0 Zulu Reference

Offset: UTC+03:30

Local: 19:57

DST: Standard

Day and overlap tools

Day/night UTC offset map

Zulu line highlighted

Blue tiles are night and warm tiles are daytime. Source and destination offsets are outlined, and UTC+0 is emphasized.

Meeting overlap visualizer

Work hours

Overlap guidance appears from the selected source and destination timezones.

Reference table, analytics, and history

Reference Grid

Dynamic conversion table

From	To	Zulu

Timezone Intelligence

Timezone detail panels

IANA references, live offsets, DST status, and offset history for both selected zones.

History Tools

Conversion history and favorites

Save frequent timezone routes and instantly replay your recent conversions.

Saved pairs

Recent conversions

Route Overview

Zulu to IRDT overview

Primary route

The time difference between Zulu and IRDT is exactly 4 hours and 30 minutes. IRDT is ahead of Zulu. For practical purposes: when it is noon (12:00) in Zulu, the time in IRDT is 16:30. When it is midnight (00:00) in Zulu, IRDT reads 04:30.

Common paired routes: IRDT to Zulu , Zulu to IRST , and Zulu to AFT .

Zulu

UTC+00:00

Zulu Time (UTC)

IRDT

UTC+04:30

Iran Daylight Time

Operational Use

Operational use cases

Financial trading desks operating in Worldwide (Aviation, Military, Maritime) must convert market open/close times to IRDT for counterpart coordination.

Supply chain managers use Zulu-to-IRDT conversions to align shipment tracking across Iran warehouses.

All NOTAM (Notice to Airmen) publications use Zulu time; pilots departing from Iran must convert local IRDT departure times to file flight plans.

ATC (Air Traffic Control) clearances reference Zulu exclusively—ground crew in IRDT zones decode these for gate scheduling.

Operations orders (OPORDs) specify H-hour in Zulu; ground units in IRDT territory translate these to synchronize movement.

Joint multinational exercises spanning Worldwide and Asia use Zulu as the common reference for deconfliction.

Technical Brief

Technical details

UTC offset explanation

Zulu Time (UTC) (Zulu) operates at a fixed offset of UTC+00:00. Iran Daylight Time (IRDT) maintains an offset of UTC+04:30. The net difference between these two zones is 4 hours and 30 minutes—meaning IRDT is ahead of Zulu by this amount. When converting, you add 4 hours and 30 minutes to get the equivalent IRDT reading.

Daylight saving behavior

IRDT is a daylight saving time designation. It applies during summer months when clocks advance by one hour from IRST. During winter, the region reverts to IRST (UTC+03:30). Always verify whether DST is currently active before relying on a conversion.

Additional notes

In the NATO military time zone system, Zulu is designated by the letter "Z" and IRDT corresponds to "—". These single-letter codes appear in Date Time Group (DTG) formatted messages used across all NATO member forces.

Iran Daylight Time is the civil time standard for approximately Iran. Major cities operating on IRDT include business, aviation, and governmental hubs that require constant coordination with UTC-referenced systems.

Cloud infrastructure providers (AWS, Azure, GCP) log events in UTC/Zulu by default. Engineers troubleshooting incidents in IRDT regions must convert log timestamps to correlate with local observations. A 4 hours and 30 minutes mental adjustment is required for every log entry.

The non-integer hour offset of IRDT (UTC+04:30) adds complexity to automated scheduling systems. Many cron-based tools and calendar applications handle whole-hour offsets natively but require explicit configuration for 30-minute fractional zones.

In-Depth Guide

Everything you need to know

Iran Daylight Time

Zulu Time to Iran Daylight Time (IRDT)

Iran Daylight Time (IRDT) is the daylight saving time zone historically observed across **Iran**. Positioned at a fractional offset of **UTC+4:30**, IRDT is exactly **four hours and thirty minutes ahead of Zulu time**. In September 2022, Iran officially and permanently abolished Daylight Saving Time (DST). Consequently, while IRDT is a critical historical timezone reference, Iran now observes standard IRST (UTC+3:30) year-round.

Conversion Logic

Understanding the Fractional Zulu to IRDT +4:30 Offset

Quick Reference

Zulu to IRDT Hourly Conversion Chart

This table converts standard Zulu times into Iran Daylight Time (UTC+4:30). Note how late afternoon and evening Zulu times at or after 19:30Z roll over into the next day (`+1 Day`) locally in Tehran.

Zulu Time (Z)	IRDT (UTC+4:30)	Day Change?	Standard Operational Context
0000Z	04:30 IRDT	Same Day	Sunrise preparations / morning slots
0400Z	08:30 IRDT	Same Day	Tehran local business day start
0800Z	12:30 IRDT	Same Day	Midday airline coordination / lunch periods
1100Z	15:30 IRDT	Same Day	Afternoon regional overflights
1200Z	16:30 IRDT	Same Day	Peak flight operations / slot coordinations
1500Z	19:30 IRDT	Same Day	Evening departures and regional flights
1800Z	22:30 IRDT	Same Day	Late night operations / international corridor control
1930Z	00:00 IRDT	+1 Day	Midnight crossing point - shifts to next day
2000Z	00:30 IRDT	+1 Day	Early morning overnight transits
2300Z	03:30 IRDT	+1 Day	Dawn overflights coordination

Mental Math

Mental Math Steps: Converting Zulu to IRDT

IRDT is 4 hours and 30 minutes ahead of Zulu (UTC). Since this is a fractional timezone, use this structured mental calculation routine:

Add 4 Hours to Zulu Hour Start by adding 4 hours to the Zulu hour value. For example, if it is 10:15Z, add 4 to 10 to get 14.

Add 30 Minutes to Zulu Minutes Add 30 minutes to the Zulu minutes. In our example: 15 + 30 = 45. Thus, 10:15Z becomes 14:45 IRDT.

Resolve Hour Overflow (>60 min) If the minutes sum is 60 or greater, subtract 60 minutes and add 1 extra hour (e.g. 10:45Z + 4h 30m = 14:75 = 15:15 IRDT). Finally, if hours exceed 24, subtract 24 and increment the day.

Geographic Zones

Regions Historically Observing Iran Daylight Time

Islamic Republic of Iran Observed during summer months until September 2022 to optimize daylight consumption across the plateau.

Tehran Imam Khomeini Airport (IKA / OIIE) The primary international hub. Summer schedules historically shifted local arrivals by one hour to align with IRDT.

Tehran FIR (OIIX Airspace) High-altitude transit routes. Handovers remained aligned with absolute Zulu time, completely unaffected by local daylight saving transitions.

Edge Cases

Essential Zulu to IRDT Conversion Rules

The 30-Minute Offset Carry: Because IRDT is offset by a fractional +30 minutes, adding the offset requires extra care. If adding 4.5 hours to 10:45Z, carry the minutes forward (10:45Z + 4:30 = 14:75 = 15:15 IRDT).

Date Rollover starts at 19:30Z: Because IRDT is 4.5 hours ahead of Zulu, the local day rollover occurs at exactly 19:30 Zulu time. Any flight plan timestamped after 19:30Z rolls over into the next calendar day in Tehran.

DST Permanent Abolition (2022): Iran abolished daylight saving shifts in September 2022. Iran now stays permanently on standard IRST (UTC+3:30) all year round. IRDT remains highly relevant for analyzing historical logs and past flight records.

Aviation Focus

Tehran FIR (OIIX) Airspace Coordination

Tehran Air Traffic Control manages high-level transit routes linking Europe with East Asia and the Persian Gulf. Pilots and dispatchers synchronize transit points entirely in Zulu time, while local ground logistics map to IRDT.

Tehran FIR (OIIX) High-altitude overflights use absolute Zulu time for safety checkpoints. Translating boundaries into local UTC+4:30 is only required for local airport slot allocations and arrival schedules in summer months historically.

FAQ

Zulu to IRDT — Frequently Asked Questions

What is IRDT and its offset from Zulu time?

IRDT stands for Iran Daylight Time. It operates at a standard offset of UTC+4:30 (four hours and thirty minutes ahead of Zulu/UTC time) when daylight saving time was historically observed.

How do I convert Zulu time to IRDT?

To convert Zulu to IRDT, add exactly 4 hours and 30 minutes to the Zulu time. For example, 12:00Z becomes 16:30 IRDT. When adding to minutes, remember to carry over the hour if the sum exceeds 60 minutes.

Does Iran currently observe Daylight Saving Time (DST)?

No. Iran officially and permanently abolished daylight saving time in September 2022. Iran now stays on standard IRST (UTC+3:30) all year round. IRDT is used only for historical and legacy data.

Why does Iran use a half-hour (+30 mins) offset?

Iran uses fractional offsets to align solar noon with the central meridian of the country, providing a more natural daylight alignment across the Iranian plateau.

When does the calendar date rollover to the next day in IRDT?

Under IRDT, the local day rolls over to the next calendar date when Zulu time reaches 19:30Z. Any Zulu timestamp at or after 19:30Z represents the next calendar day locally in Tehran (00:00 IRDT).

Why do trans-continental flights use Zulu instead of IRDT over Tehran FIR?

Because high-altitude flights cross boundaries rapidly, coordinating slots and handovers in local fractional times like UTC+4:30 increases the risk of timing errors. Absolute Zulu time serves as the unified standard for regional controllers and pilots.

How do I coordinate slots at Tehran Imam Khomeini Airport?

Flight plan filing, slot allocations, and active cockpit logs must utilize Zulu time. Local IRDT coordinates passenger ticketing, airport ground crews, and public schedules.

Why did Iran legally abolish daylight saving time (IRDT) in 2022?

The Iranian parliament abolished DST to reduce confusion, prevent disruption of domestic schedules, align with biological rhythms, and simplify international communications. Similar actions have been taken by nearby countries like Turkey.

Is IRDT ever used for active operations today?

No, IRDT is no longer actively observed by any civil or military organizations. It is preserved in global software databases and on converter sites exclusively for historical analysis, logs auditing, and backward compatibility.