TRUECALC
Functions

TZDIFF

Elapsed time from b to a on the absolute timeline (DST-immune)

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When to use it

When should I use TZDIFF instead of subtracting two date serials?

Use TZDIFF when the two timestamps are in different time zones or span a DST transition. Serial subtraction counts wall-clock ticks and can be off by an hour; TZDIFF works on the absolute UTC timeline so it always returns real elapsed time.

What happens when TZDIFF is called across a daylight-saving boundary?

TZDIFF ignores DST changes entirely and counts only real elapsed seconds on the UTC timeline, so a one-hour clock-change has no effect on the result.

Which unit should I choose for cross-zone SLA or latency measurements?

Use "minutes" or "seconds" for precise SLA checks, "hours" for shift or flight durations, and "days" for multi-day turnaround reporting.

Use cases

Calculate SLA breach time in minutes between two cities

Compute elapsed days for a multi-region trade settlement

Used in

finance · operations · logistics

Syntax

TZDIFF(zoned_a,zoned_b,[unit])

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