Short answer: order for everyone who said yes, plus a 5–10% buffer, using a standard size curve for anyone who didn't reply. Here's the exact math organizers actually use — for a class of 30, a team of 20, or a company floor of 50.
Calculate your group shirt size breakdown
FREE PLANNING TOOL
Turn one headcount into a complete size list
Use actual responses whenever possible. This estimate is for missing replies and extra shirts.| Size | Planning share | Quantity |
|---|---|---|
| Youth S | 0% | 0 |
| Youth M | 0% | 0 |
| Youth L | 0% | 0 |
| Adult S | 10% | 5 |
| Adult M | 25% | 14 |
| Adult L | 30% | 16 |
| Adult XL | 20% | 11 |
| Adult 2XL | 10% | 5 |
| Adult 3XL | 5% | 3 |
Mixed adult curve · weighted toward M, L, and XL. Always confirm extended sizes rather than guessing.
The buffer rule: +5–10%, always round up
Every group order has three predictable surprises: someone joins late, someone's size was wrong, and one shirt gets damaged or lost. A buffer costs a few dollars per extra shirt on a bulk order — a reorder later costs full setup, a second shipment, and two weeks. The rule:
- Under 30 people: add 2–3 extra shirts.
- 30–75 people: add 8–10%.
- 75+ people: add 5–8%, weighted toward M/L/XL.
The standard US adult size curve
When some people never send their size (they won't), distribute the unknowns on this curve — it matches what apparel wholesalers see across mixed adult groups:
- S — 10%
- M — 25%
- L — 30%
- XL — 20%
- 2XL — 10%
- 3XL — 5%
So for a class of 30: about 3 S, 7–8 M, 9 L, 6 XL, 3 2XL, 1–2 3XL, plus 2–3 buffer shirts in M/L/XL. For a team of 20, shift one size up if it's an adult men's team; for a mixed or student group, shift one size down.
Collecting sizes without chasing people
- Set a deadline with a default: "Reply with your size by Friday — no reply means you get a Large." The default does the chasing for you.
- Use one shared sheet, not DMs. One column: name, size. Done.
- Ask for fit preference, not measurements. "True to size / size up" catches the hoodie-over-uniform crowd.
- Don't wait for the last two people. Assign them the curve and move on — that's what the buffer is for.
Mixed sizes don't cost extra (here's why)
With modern DTF printing, a bulk order is priced by total quantity and print design, not by size split — 30 shirts in six sizes cost the same as 30 shirts in one size (only oversize garments like 3XL+ sometimes carry a small blank-cost difference). So never shrink your size range to "simplify" the order. You can even mix hoodies and tees in one order →
Youth sizes for schools and families
For school spirit wear and family reunions, expect roughly one youth shirt for every three adults in a family-based group. Youth S/M/L covers ages 6–12 for most brands; when in doubt, size up — kids grow into shirts, never out of the group photo. Family reunion shirts → · School spirit wear →
The organizer's one-page checklist
- Confirmed headcount + 5–10% buffer
- Unknown sizes → standard curve above
- Sizes locked by a deadline with a Large default
- Youth sizes counted separately (schools/families)
- Free mockup approved before anything is printed
Send us your headcount — even a rough one — and a real designer returns a free mockup within 24 hours, with the size sheet template included. You approve before you pay a cent. Get a free quote →
