Time Zone Converter Calculator Formula

Understand the math behind the time zone converter calculator. Each variable explained with a worked example.

Use the Time Zone Converter Calculator

Formulas Used

Target Time (24hr)

target_hour = raw_target >= 0 ? (raw_target < 24 ? raw_target : raw_target - 24) : raw_target + 24

Time Difference

hour_difference = abs(offset_diff)

Variables

VariableDescriptionDefault
source_hourSource Time (24hr)14
source_offsetSource UTC Offset(hrs)-5
target_offsetTarget UTC Offset(hrs)1
offset_diffDerived value= target_offset - source_offsetcalculated
raw_targetDerived value= source_hour + offset_diffcalculated

How It Works

How Time Zone Conversion Works

Each time zone is defined as an offset from UTC (Coordinated Universal Time). To convert, calculate the difference in offsets and add it to the source time.

Formula

Target Time = Source Time + (Target UTC Offset - Source UTC Offset)

If the result is negative, add 24 (previous day). If over 23, subtract 24 (next day).

Worked Example

It is 14:00 (2 PM) in UTC-5 (New York). What time is it in UTC+1 (Paris)?

source_hour = 14source_offset = -5target_offset = 1
  1. 01Offset difference = 1 - (-5) = 6 hours
  2. 02Target time = 14 + 6 = 20:00 (8 PM)
  3. 03Paris is 6 hours ahead of New York

Frequently Asked Questions

What does UTC mean?

UTC stands for Coordinated Universal Time. It is the global time standard from which all time zones are defined as positive or negative offsets.

What about daylight saving time?

DST shifts the UTC offset by 1 hour during summer months. Check whether your region observes DST and adjust the offset accordingly.

What are common UTC offsets?

US Eastern: UTC-5 (EST) / UTC-4 (EDT). US Pacific: UTC-8 / UTC-7. UK: UTC+0 / UTC+1. Central Europe: UTC+1 / UTC+2. Japan: UTC+9. India: UTC+5:30.

Learn More

Guide

Time Zone Conversion Guide - How to Convert Between Time Zones

Learn how to convert between time zones accurately. Covers UTC offsets, daylight saving time, the International Date Line, and scheduling across multiple zones.

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