Timezone offset difference

Offsets outside plus or minus fourteen hours are rejected with invalid_input.

Fixed UTC offsets versus named time zones

By keeping the contract to fixed numbers in the closed interval from minus fourteen through plus fourteen hours, the tool stays predictable for spreadsheets, API tests, and travel notes that already print UTC± labels.

How to call the API and read the response

Send a JSON body with required finite numbers offset_a and offset_b (aliases include a, from_offset, offset_from, utc_a for the first, and b, to_offset, offset_to, utc_b for the second), each within minus fourteen to plus fourteen inclusive, plus required integer hour_a from zero through twenty-three for the local hour at A. Optional minute_a defaults to zero and must be an integer from zero through fifty-nine when present. On success the response echoes rounded offsets and the input clock, publishes offset_a_label and offset_b_label as short UTC± strings, sets hour_diff to offset_b minus offset_a, abs_diff_hours to the absolute value of that difference, hour_b and minute_b and time_b for the mapped clock at B, day_offset for how many midnights were crossed when adding the difference, day_note and direction as short English summaries, message as a one-line result, and steps as an ordered array of substitution lines. Failed validation—missing fields, non-finite numbers, non-integer hour or minute, hour outside zero to twenty-three, minute outside zero to fifty-nine, or any offset whose absolute value exceeds fourteen hours—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, limits, and related searches

Keep offsets inside the published plus-or-minus fourteen hour window; values such as fifteen or minus fourteen point one are rejected so callers cannot invent impossible civil offsets. Prefer fractional hours for half-hour and three-quarter-hour zones—five point five for India, five point seven five for Nepal, nine point five for parts of Australia—rather than smuggling minutes into a second field that does not exist for the offset itself. Prefer this capability when both ends already publish fixed UTC± labels; if you only have city names, resolve offsets first or use a DST-aware zone tool. When mapping a local clock, remember the signed difference is always B minus A: if A is UTC plus two and B is UTC minus five, hour_diff is minus seven, so fifteen thirty at A becomes eight thirty the same calendar day at B. Crossing midnight sets day_offset to plus one or minus one and the day_note string explains which side of midnight B lands on relative to A. Pair examples when teaching: same offset leaves the clock unchanged; whole-hour westbound travel subtracts hours; eastbound adds hours; a half-hour offset produces a thirty-minute shift; an out-of-range offset demonstrates the hard invalid_input path. This landing targets people searching for timezone offset difference, UTC offset hours between two places, or local time given two fixed offsets; it is not a flight-duration calculator, not a daylight-saving advisor, and not a city-name zone converter. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately send offset fifteen. Round-trip checks are easy: recompute offset_b minus offset_a by hand and confirm it equals hour_diff, then add that many hours to time_a and confirm time_b and day_offset match after twenty-four-hour wrap.