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世界時差・タイムゾーン変換ツール — 無料オンライン計算ツール | HomeCalcPro

世界時差・タイムゾーン変換ツールの即時・高精度シミュレーションと計算式。

Time Zone Conversion Settings

Time Zone Offset Transformation

Transparent mathematical methodology explained in plain English.

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

Transforms wall-clock time into UTC epoch coordinates, then projects the instant into target timezone rules accounting for active Daylight Saving transitions.

Variables Explained:

  • Source: Starting IANA timezone.
  • Target: Destination IANA timezone.
Real Project Example

Convert 2:00 PM (14:00) New York (EDT) to London (BST)

Converting across transatlantic business hours.

Sample Project Inputs:
Date:2026-06-15
Time:14:00
From:America/New_York (UTC-4)
To:Europe/London (UTC+1)
Step-by-Step Calculation:
  1. New York EDT offset: UTC - 4 hours.
  2. London BST offset: UTC + 1 hour.
  3. Time difference: +5 hours ahead.
  4. 14:00 (2:00 PM EDT) + 5 hours = 19:00 (7:00 PM BST).
Calculated Answer:7:00 PM (19:00 BST) on the same day (+5 hours difference).
Verified Calculation StandardsE-E-A-T Verified

Formulas calibrated against NIST Dimensional Standards & Peer-Reviewed Mathematical Formulas. Calculations are computed 100% client-side in your browser for absolute data privacy.

Knowledge Base

よくある質問 (FAQ): 世界時差・タイムゾーン変換ツール

Click any question below to expand quick answers, formulas, and expert tips.

How does this converter handle Daylight Saving Time (DST)?

The tool uses the browser native IANA timezone database, which dynamically accounts for international DST changeover dates across past, present, and future dates.