How We Ran a 406-Team Tournament: 755 Matches, Six Categories [Case Study]

In 2025 we ran the IIUM Robotics Competition: 406 teams, 755 matches, six competition categories — all drawn, scheduled and scored on one system. That's just under two matches per team on average, and every one of them had to end up in the right place, at the right time, in front of the right referee.

Here's the thing nobody warns you about: at that scale, the size isn't the hard part. The hard part is that your entry list is still wrong on the morning of the event — and every fix you make ripples through six brackets at once. This is the write-up I wish I'd read first.

Key Takeaways

• 406 teams and 755 matches across six categories — six separate tournaments sharing one venue and one clock.
• Teams don't arrive as independent entries. They arrive in clumps from the same school, and a random draw will happily put four of them in one group.
• Uneven group sizes mean uneven match counts — a team in a group of three plays two games, a team in a group of four plays three.
• The registration list keeps changing until the first whistle. No-shows, walk-ins, duplicate names, failed inspections.
• The single most useful property of any tool at this scale: you can redraw in seconds. A draw you can't rerun is a draw you can't fix.

What IRC 2025 Actually Was

The IIUM Robotics Competition runs six categories side by side:

• Robot soccer — primary school
• Robot soccer — secondary school
• Autonomous sumo — 500g, 1kg and 3kg weight classes
• Manual sumo

That framing matters more than the headline number. 406 teams isn't one big tournament. It's six tournaments, each with its own draw, its own bracket, its own standings — running at the same time, in the same building, competing for the same arenas and the same referees.

Once you see it that way, the problem changes shape. You're not solving a big bracket. You're solving six medium brackets that all want the same resources at the same moment.

Why 406 Teams Breaks a Spreadsheet

A spreadsheet can hold 406 rows. That was never the issue. The issue is checking.

Say you split a category into groups of four. Every group of four contains six possible pairings. A category with 100 groups gives you 600 pairs to eyeball for school clashes — and that's one category, checked once.

Now change one entry. A team withdraws. Every group after it shifts, and you check all 600 pairs again.

That's the wall. It isn't capacity, it's the recheck cost of every single change. I've written separately about where spreadsheet brackets stop working — this event is the version of that story with the volume turned up.

The Three Things That Actually Went Wrong

1. Teams From the Same School Kept Landing Together

A random draw doesn't know what a school is. One school enters fifteen teams, and the draw cheerfully puts four of them in the same group.

Two reasons that hurts. The obvious one: the school knocks itself out before the competition has properly started. The subtle one is worse — parents and coaches notice, and a draw that produced it by pure chance still looks arranged.

You cannot win that argument at a desk on match day. You can only avoid having it, by keeping same-school teams apart in the draw and being able to reshuffle a group when one slips through.

2. Groups Came Out Unbalanced

Entry counts are never tidy. A category with 67 teams does not split into equal groups of four, so you end up with a mix — some groups of four, some of three.

A team in a group of four plays three matches. A team in a group of three plays two. Same entry fee, same travel, one fewer game — and different fatigue going into the knockout. If you've promised everyone a set number of games, uneven groups quietly break that promise.

Decide the rule before the draw, not during it. Either keep every group the same size within a category and absorb the remainder elsewhere, or accept the imbalance and say so in the rules. What you can't do is discover it on the day. The mechanics of a group stage feeding a knockout are worth reading before you commit to group sizes.

3. The Entry List Was Wrong Until the Morning

This is the one that actually breaks things.

Teams register and don't show up. Teams show up that never registered. Two teams have the same name. A robot fails inspection and its team is out before it plays a match.

Every one of those is a small administrative event. Together, on the morning of a 406-team competition, they mean the bracket you printed last night no longer describes the room you're standing in.

If regenerating the draw takes an evening, you don't regenerate it. You patch it by hand, badly, under time pressure, and the errors you introduce surface three rounds later when someone's already gone home.

What Actually Held It Together

Four capabilities did the heavy lifting, and they're worth naming because they're the ones I'd now check for in any tool before running an event this size.

• Auto-filled brackets, random or seeded. Populate a whole category in one action, either drawn at random or placed by seed so the strongest entries stay apart.
• Drag-and-drop reordering. No algorithm knows that two teams share a bus, or that a school needs to leave by four. Human overrides aren't a fallback here — they're a requirement.
• Regeneration in seconds. This is the one that changes behaviour. When redrawing is instant, you fix problems instead of living with them.
• PDF export. Referees and desk staff want paper. Paper doesn't need a signal and doesn't run out of battery. Being digital doesn't mean refusing to print.

That combination is what Tournamyx was built around, and IRC is the event that shaped it — you can try the bracket generator without signing up for anything.

What I'd Do Differently

Lock the entry list earlier, and mean it. Every late change costs more than it looks like it costs, because it re-triggers every check you already did.

Write the group-size rule into the rulebook before the draw. "Groups of four where possible, groups of three where the numbers don't divide" takes one line and prevents an argument.

Treat check-in as a stage of the event, not a formality. The draw should be finalised after check-in closes, not before. That single reordering removes most of the morning's chaos.

Do the arena maths before the format maths. It's tempting to design the perfect format and then find space for it. It works far better the other way around — work out what your venue can physically absorb and pick a format that fits inside it.

Frequently Asked Questions

How many matches does a 406-team tournament need?

Ours came to 755, which is just under two matches per team — but that number is a product of the format, not the field size. A straight knockout for 406 teams would need only 405 matches. Group stages push it up, because everyone plays two or three games before anyone goes home. The match-count formula for each format will tell you your own number.

Can you really run six categories at the same time?

Yes, if you treat them as six independent tournaments that happen to share arenas and referees. Trouble starts when you try to merge them into one schedule. Keep the draws separate and manage the venue as the shared resource.

What's the biggest risk at this scale?

The entry list, every time. Not the format, not the bracket, not the scoring. The gap between who registered and who actually walked through the door is where large events lose their morning.

Do you need software for a tournament this big?

For 406 teams across six categories, honestly, yes — but the reason isn't the drawing. It's the redrawing. If your method can't absorb a changed entry list in under a minute, the size of the field will eventually beat you.

The One Lesson Worth Keeping

406 teams and 755 matches sounds like a scale problem. It isn't. It's a change problem.

A tournament of any size is fine while nothing moves. What makes a big one hard is that things move constantly — and every movement asks you to re-verify work you'd already finished. Pick your format, your tooling and your deadlines so that changing your mind stays cheap.

If you're planning something large, start with the complete guide to organizing a tournament, then build your draw in Tournamyx Scores — free to set up, and it redraws in seconds when the entry list changes on you. Because it will.