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

Ready to run the numbers?

Open Time Zone Converter Calculator