A few weeks ago we wrote about why "3pm" means nothing when you teach across timezones. The short version: DST changes at different dates in different countries, students and tutors silently disagree on when the lesson is, and people stop showing up. Nobody argues. They just leave.
So we built something.
A Free Timezone Converter, Right on Our Homepage
Starting today, there's a timezone converter on the SandGlass homepage. No signup. No account. No catch.
Pick your timezone, pick your student's, choose a lesson date and time, and see the conversion instantly. That's it.
It auto-detects your timezone when you open the page, so half the work is already done. Select the student's timezone from the dropdown, pick a time slot, and you'll see exactly what that lesson looks like on their end — including the date, which matters more than you'd think.
DST-Aware, Not Just Offset Math
Most timezone converters do simple arithmetic: "Tokyo is UTC+9, New York is UTC-5, so the difference is 14 hours." That works until it doesn't.
On March 8, 2026, the US springs forward. Europe doesn't move until March 29. For those three weeks, a tutor in Berlin and a student in Chicago aren't 7 hours apart — they're 6. If your converter just subtracts fixed offsets, it gets this wrong.
Ours doesn't. It uses your browser's built-in timezone database, which knows exactly when every country's clocks change. Pick March 15 and you'll see the adjusted offset. Pick April 1 and it shifts back. You don't have to think about it — but the math is right either way.
The Edge Cases That Trip People Up
Timezone conversion isn't just about whole-hour offsets. A few things that this tool handles correctly:
Half-hour and 45-minute offsets. India is UTC+5:30. Iran is UTC+3:30. Nepal is UTC+5:45. Newfoundland is UTC-3:30. If you have students in any of these places, a "14 hours apart" mental shortcut won't cut it.
Date-line crossings. When it's 8pm Tuesday for you in London, it's already 5am Wednesday for your student in Tokyo. The converter shows both dates, and flags a warning when they differ. This matters — telling a student "see you Tuesday" when it's Wednesday for them is how lessons get missed.
Southern hemisphere DST. Australia, New Zealand, Chile, and parts of Brazil observe DST in the opposite direction from the northern hemisphere. When Europe springs forward, Sydney falls back. The overlap creates a period where the offset between, say, Amsterdam and Melbourne swings by two hours in a few weeks.
Why Give It Away?
Because a timezone converter shouldn't be a product. It should be a solved problem.
We built this because tutors shouldn't have to open a separate tab, type two city names, squint at a result, and then copy-paste it into a message. That workflow is absurd for something a computer can do in milliseconds. So we put it where tutors already are — on a page about tutoring tools.
If it saves you from one missed lesson, it's worth it.
But a Converter Isn't the Real Fix
Here's the thing: a converter solves one query at a time. You look up one student's timezone for one lesson on one date.
If you have fifteen students across eight timezones, you'd use it dozens of times a week. Before every reschedule message. Before every "can we move to Thursday?" reply. Before every new student's first booking.
The real fix isn't a better converter. It's a system where you never have to convert at all.
That's what SandGlass does. You set your availability once, in your own timezone. When a student looks at your schedule, they see it in their local time — automatically converted, DST-aware, no math required. You see "Tuesday 6pm." They see "Tuesday 9am." Same moment. Neither of you thinks about it.
The converter on our homepage is a taste of that. Use it whenever you need a quick check. But if you're tired of doing the check at all, that's what the full product is for.
Try the converter now — or sign up for SandGlass and let it handle every conversion automatically. No commission, no percentage fees, just a flat €12/month after the free tier.
This is part of our series on building a sustainable independent tutoring practice. Previously: The Timezone Trap: Why 3PM Means Nothing.