Ordering shirts for an event sounds like a logistics footnote until you're standing at the pickup table with forty extra XLs and a line of frustrated mediums. The math is not complicated. The problem is that most first-timers skip the math entirely and order on instinct, which is how you end up haunted by a bin of unsold inventory in the corner of your garage.
How many event shirts should you actually order?
Your confirmed registration count is your floor, not your target. Whatever that number is the week before your order deadline, take 85 to 90 percent of it. Registered attendance at free or low-cost events reliably runs 15 to 20 percent lower than sign-ups, and paid events still see 5 to 10 percent no-shows on average.
Start with confirmed headcount, not capacity. If you registered 300 people for a 5K and your venue holds 500, you are not ordering 500 shirts. You are ordering something in the neighborhood of 255 to 270, plus a small buffer we'll get to in a minute.
Factor in your staff and volunteers before you finalize. A 10-person crew that wants shirts is 10 shirts you need to account for in specific sizes, not a vague "add some extras." Pull staff sizes first, set them aside mentally, and then build your attendee order. Mixing them into a general buffer means you'll run short on a size that three of your volunteers need.
One more thing worth saying plainly: do not add shirts because shirts feel like a nice thing to have around. Every extra shirt you order is dead money until proven otherwise.
Why your gut feeling about size mix will cost you money
The default assumption most organizers make is something like "half the crowd is medium or large, so I'll split it roughly even and hedge with a few smalls and XLs." That logic sounds reasonable and produces a size mix that will leave you with smalls nobody wants and XLs that sold out in the first twenty minutes.
Real event attendance data skews harder toward the middle than most people expect. The American Apparel & Footwear Association's annual size study consistently shows that the average American adult male measures into an L or XL, and the average adult female purchases at the M or L depending on the brand's women's versus unisex cut. At a mixed adult event with unisex shirts, that pushes your bulk dramatically toward M through XL.
The 50/50 mental model is where the money disappears. You end up over-buying smalls and extra-smalls that go untouched, and then scrambling when you hit the bottom of your medium stack by noon.
What makes this worse is that the financial pain is asymmetrical. Running out of a size makes someone angry at your event in real time, in front of other people. Having leftover smalls is a quieter failure that you feel later, when you're tallying the actual cost per shirt against how many you distributed. Both outcomes are bad. The second one just doesn't yell at you.
Recommended starting points
5 picksBuilding a size mix that tracks your actual crowd
If you have registration data that includes shirt size, use it. This sounds obvious, but a surprising number of organizers collect size information during sign-up and then ignore it when they actually place their order because the split "looks weird." Trust your data over your instincts. If 38 percent of your registrants selected L, order 38 percent L.
If you don't have size data, segment by what you do know. A trail run or a cycling event skews smaller and more athletic, which tends to pull sizing toward M and S more than a general charity walk. A corporate team-building day with a mix of office workers across age brackets skews toward L and XL. A youth sports tournament means you need youth sizes, which is a whole separate conversation about XS through L in kids' cuts.
Weight toward your top two sizes, not your full range. For most mixed adult events, that means putting roughly 60 to 65 percent of your total order into M and L together. A workable default that consistently causes fewer problems than the gut-feel approach looks something like this:
| Size | Suggested Share | Notes |
|---|---|---|
| S | 5% | Lower at mixed or older crowds |
| M | 28–30% | Usually your second-largest need |
| L | 33–35% | Typically the highest-demand size |
| XL | 18–20% | Increases at trades, outdoor, older crowds |
| 2XL | 8–10% | Don't skip this; running out is painful |
| 3XL | 2–3% | Only if your data supports it |
You can run these numbers through the 5K Shirt-Size Calculator if you want a faster, tailored split based on your headcount and audience type.
The small buffer that prevents scrambling at pickup
A buffer is not a second order in disguise. Five to ten percent over your confirmed attendance estimate, applied only to your highest-demand sizes, is insurance against two real problems: day-of walk-up registrations and miscounts in your own fulfillment process.
Apply the buffer to M and L only. If you're ordering 250 shirts and your mix calls for 87 larges, rounding up to 95 or so is sensible. Ordering 10 extra smalls because you're nervous is not. Walk-ups never arrive in the size you're overstocked in.
Day-of walk-ups at free events can run surprisingly high, sometimes 8 to 12 percent above confirmed registration, especially for community 5Ks and charity events where casual participation is encouraged. Paid events with pre-ordered shirts attached to registration are more predictable, which means your buffer at a paid race can sit at the low end of that range.
The other thing a small buffer protects against is human error in your own pickup system. Misfiles, miscounts, shirts handed to the wrong person, a box that got left in a car trunk, staff who grabbed the wrong size. Five percent over is not wasteful. It's acknowledging that logistics done by humans has a natural error rate.
Not sure what fits your headcount and budget?
When you should just order fewer shirts
This section exists because the pressure to feel generous with swag leads organizers into orders they genuinely cannot justify. If you're staring at a per-shirt cost that's straining your budget and you're compensating by telling yourself someone will buy the extras later, stop. Order fewer shirts.
Fewer shirts at the right sizes beats more shirts at the wrong ones. A tighter, better-targeted order that covers 85 percent of your actual attendance and gets the size mix right leaves attendees happy and costs you less than an inflated order with a bin of unsold XS shirts you're still looking at three months from now.
Consider whether some attendees genuinely need a shirt at all. Staff and volunteers almost always benefit from a shirt because it identifies them. Registered participants in a race or walk usually expect one as part of registration. But if you're running a corporate event where the shirt is a nice-to-have and not a logistical necessity, trimming the order by 15 to 20 percent is a reasonable call.
Smaller orders do cost more per unit, and that's worth knowing before you cut too aggressively. Dropping from 250 to 150 shirts can push your per-piece cost up meaningfully, sometimes by $2 to $4 depending on the decorator and garment. That relationship between quantity and unit price is worth reading through in detail, and this breakdown of what 100 shirts actually cost walks through the numbers without softening them.
If the math doesn't work at any quantity, the honest answer is to reconsider whether shirts are the right item for this event at all.
Printing on existing inventory instead of gambling on quantity
There is a version of this problem that sidesteps quantity guessing almost entirely. Buy plain, undecorated shirts in the exact sizes you confirmed through registration, then send them out for printing. This approach is more work upfront and requires a decorator who will work with supplied blanks, but it eliminates the guessing game on quantity because you're only printing shirts you know you're distributing.
Blanks are cheap. Printing on wrong-size blanks is expensive. A Bella+Canvas 3001 in unisex runs around $4 to $6 per shirt at retail, less if you buy wholesale. If you collect exact sizes at registration, your waste is near zero. You're not trying to predict a distribution. You're filling confirmed orders.
The tradeoff is lead time and logistics. You need to buy blanks, warehouse them briefly, ship to a decorator, and coordinate pickup or fulfillment. That adds steps and a few days. For an event that collects size information at registration and has a stable attendee count, it's often worth it. For a walk-up-heavy event where attendance is genuinely unpredictable, it's less useful because you still have to estimate what you'll need on the floor.
Some decorators won't accept customer-supplied blanks, or they'll charge a fee that erodes the savings. Ask before you commit. If your decorator is flexible, this model is one of the cleaner ways to run event shirts the first time.
The organizers who end up shipping leftover shirts to a storage unit are not the ones who ordered too carefully. They're the ones who rounded up just in case.