Use the free tool above, then read on for how it works, a worked example, and practical tips.
What this tool does
Amateur radio logs use UTC, but operators think in local time, and a contact logged in the wrong hour can fail to match the other station’s log. This converter turns a date and time in one zone into UTC and several common zones at once, so your log entries line up with the station you worked.
How it works
The tool treats your entered time as local time in the zone you choose, converts it to UTC by subtracting that zone’s offset, and then adds each target zone’s offset to show the same moment around the world. It uses fixed offsets, which keeps the maths clear and matches how most contest and log software displays standard zone times.
How to use it
- Enter your values in the boxes above.
- Press the calculate or play button.
- Read the result shown below the tool.
- Try a second set of values to compare options.
Worked example
A contact at 12:00 Central European time is 11:00 UTC, which is 06:00 on the US East Coast and 20:00 in Japan on the same day. If you logged it as 12:00 UTC by mistake, the other station’s log would show a full hour of difference and a confirmation system could refuse the match.
Practical tips
Always write UTC in your log, and write the date in UTC too, because a late-evening local contact can fall on the next UTC day. When arranging a sked, confirm the time in UTC in the message itself, not just in your local time, so both stations arrive on the same hour.
Common mistakes
The classic mistake is logging local time as if it were UTC, especially after a trip or after daylight saving changes. Another is forgetting that the UTC date changes first in the east, so a contact near midnight can sit on a different date in each station’s log.
Questions and answers
Is this tool free? Yes. It runs in your browser, needs no account, and gives instant results.
Do I need to install anything? No. The tool works on any modern phone or computer browser.
How accurate are the results? The maths follows the standard formulas shown above. Real-world results vary with terrain, equipment, and conditions, so use the figures for planning.
Can I use it on my phone? Yes. The tool is designed to work on a phone screen, so you can use it at the operating desk, in the field, or at a club station without a computer.
Who uses this tool
Radio amateurs, students, and club members all use tools like this one, because they turn a formula from a book into an answer for your own station in seconds. Beginners use it to check homework and first setups, while experienced operators use it to sanity-check a plan before spending money on cable, masts, or antennas. Even a quick check can prevent a costly mistake, such as ordering the wrong cable length or aiming a beam in the wrong direction.
What to try next
- Run the tool with your real station values, not just the default numbers, so the answer means something for your setup.
- Change one input at a time and watch how the result moves, because that shows you which input matters most.
- Write the result in your station notebook next to the date, so you can compare later changes against a known baseline.
Safety note: this is an educational estimator only. Real transmissions need an amateur licence and must follow your local regulations, band plans, and power limits. Never transmit without the proper licence, and treat every result here as a planning guide, not professional or legal advice.
Versión en español: Conversor de Hora QSO – Convierte Horas de Contactos a UTC para tu Libro de Guardia