How to divide sizes for a group order?

AuthorFondatore Custoomyeditor

Reading8 min

Updated01 April 2026

The ideal size distribution for a group order depends on three main variables: the demographic target (age, gender, context), the garment type (t-shirt, sweatshirt, polo shirt) and the brand's fit. There's no universal formula, but there are reliable statistical curves for each segment. For a generic mixed group of adults, the peak is on size L, with an asymmetrical curve shifted towards larger sizes. For university students and female athletes, the peak drops to M; for corporate employees and seniors, it shifts towards XL. In this article you'll find distribution tables for 12 different segments, the main modifiers to apply and how to avoid the most common mistakes that generate leftover stock and costly reorders.

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The problem no one tells you before ordering

You've decided to make 100 t-shirts for your team, event or company. The supplier asks how many for each size. Complete block.

The most common reaction is ordering equal quantities for all sizes: 14 pieces each. The almost guaranteed result is this — nobody wants the XS and XXXL, the L sizes run out on the first day, two people are left without. You need to make an urgent reorder that costs 20–30% more due to setup printing costs, and you pay for garments you'll never distribute.

This happens because the real size distribution in the Italian population is not uniform. It follows an asymmetrical bell curve that varies based on age, gender, type of activity and geographical area.

Warning

Promotional apparel suppliers estimate that sizing errors affect on average 10–20% of unplanned orders. The average cost of an urgent reorder increases the unit cost by 15–25%.

What is the size curve and why it changes everything

In the apparel sector, we talk about size curve — the percentage distribution of pieces for each size in an order. It's not an abstract concept: every experienced supplier works with different curves per segment, season and garment type.

The starting point for building a reliable curve is the SizeItaly anthropometric study (an Italian national sizing study), the largest body measurement project conducted in Italy with over 6,000 people analysed and 24,000 scans. Combining this data with ISTAT reports on excess weight and sedentary lifestyle by age group, and with order history data from international apparel printing platforms, clear and replicable statistical patterns emerge.

The variable with the greatest impact on the curve? Gender — which explains about 40% of the total variance. This is followed by the group's average age, the garment type and the specific brand.

Recommended distributions by segment

The following percentages are calibrated for unisex regular fit t-shirts — the most ordered product in group orders. For other garment types, see the dedicated section below.

Sports groups

Segment	XS	S	M	L	XL	XXL	XXXL	Peak
Mixed adult team (18–45)	5%	18%	32%	28%	12%	4%	1%	M
Men only (18–45)	1%	5%	18%	36%	28%	9%	3%	L
Women only (18–45)	8%	28%	39%	18%	6%	1%	—	M

Mixed adult team (18–45)

18%

32%

28%

12%

XXL

XXXL

Peak

Men only (18–45)

18%

36%

28%

XXL

XXXL

Peak

Women only (18–45)

28%

39%

18%

XXL

XXXL

—

Peak

Practical reading: for a mixed team of 50 people, order about 16 size M, 14 size L and 6 size XL. Always consider 1–2 extra pieces in L and XL as buffer for latecomers.

Corporate contexts

Segment	XS	S	M	L	XL	XXL	XXXL	Peak
Mixed office employees (25–55)	2%	10%	24%	30%	22%	9%	3%	L
Industry / logistics (mostly men)	1%	6%	18%	32%	26%	12%	5%	L

Mixed office employees (25–55)

10%

24%

30%

22%

XXL

XXXL

Peak

Industry / logistics (mostly men)

18%

32%

26%

XXL

12%

XXXL

Peak

Warning

Geographical gradient (ISTAT data 2023): in Southern Italy, the prevalence of excess weight is about 10 percentage points higher than in the North. For orders destined for Southern Italy, consider shifting 2–3 percentage points from S/M towards XL/XXL.

University students

Segment	XS	S	M	L	XL	XXL	XXXL	Peak
Mixed students (19–26)	5%	18%	32%	24%	14%	5%	2%	M
Men only (19–26)	2%	10%	28%	30%	18%	8%	4%	L
Women only (19–26)	10%	30%	35%	17%	6%	2%	—	M

Mixed students (19–26)

18%

32%

24%

14%

XXL

XXXL

Peak

Men only (19–26)

10%

28%

30%

18%

XXL

XXXL

Peak

Women only (19–26)

10%

30%

35%

17%

XXL

XXXL

—

Peak

Children and seniors

Primary school (6–11 years): for a mixed group without precise age information: 20% size 6A, 28% size 8A, 30% size 10A, 17% size 12A, 5% size 14A. The peak is 10A.

Lower secondary school (11–14 years): if using adult sizes XS–L, the recommended distribution is 25% XS, 40% S, 25% M, 10% L. Almost no child in this age range requires XL or above.

Senior group (55+): the curve shifts significantly to the right. Distribution: 1% XS, 6% S, 18% M, 28% L, 25% XL, 15% XXL, 7% XXXL. Don't order XS for this segment — it's almost certainly an undistributed garment.

Four factors that modify the base distribution

The tables above are a starting point, not a definitive answer. Four variables modify it significantly.

3 factors + 1 that modify the base distribution

The tables above are a starting point, not a definitive answer. Four variables modify it significantly.

IDProfilo

Hooded sweatshirts show the most pronounced "sizing up" behaviour: approximately 35% of users prefer to order one size larger for comfort and style. The base distribution should therefore be adjusted towards larger sizes compared to t-shirts in the same segment. For jackets and gilets, which are often worn over other garments, add 2–3 percentage points to XXL and XXXL compared to the base distribution. For polo shirts, the fit is usually accurate — people tend to order their true size without adjustments. The base distribution applies without modifications.

The specific brand

The sizing system is not standardised. Each brand has different actual measurements for the same letter.

Brand	Cut	Effect	Practical advice
Gildan	American boxy, generous	Those used to European brands tend to size down	Communicate the fit before ordering
Stanley / Stella	European medium fit, fitted	Those used to Gildan will need to size up	Recommend checking the size chart in cm
SOL'S	French slim fit, runs small	SOL'S M corresponds to S in many other brands	Consider +1 shift across entire distribution
B&C / Kariban	Standard European regular fit	Base distribution applicable without modifications	Neutral reference for most orders
Fruit of the Loom	Slightly tapered, standard	Base distribution applicable	Excellent starting point

Gildan

Cut

American boxy, generous

Effect

Those used to European brands tend to size down

Practical advice

Communicate the fit before ordering

Stanley / Stella

Cut

European medium fit, fitted

Effect

Those used to Gildan will need to size up

Practical advice

Recommend checking the size chart in cm

SOL'S

Cut

French slim fit, runs small

Effect

SOL'S M corresponds to S in many other brands

Practical advice

Consider +1 shift across entire distribution

B&C / Kariban

Cut

Standard European regular fit

Effect

Base distribution applicable without modifications

Practical advice

Neutral reference for most orders

Fruit of the Loom

Cut

Slightly tapered, standard

Effect

Base distribution applicable

Practical advice

Excellent starting point

Pro tip

The advice that makes the difference: when choosing a brand your participants don't know, always send the size chart in centimetres (chest width and total length) rather than relying only on XS–XXXL letters. It's the only objective data that eliminates ambiguity.

How to collect sizes reliably

Before relying on statistical distribution, assess whether you can collect individual sizes. For orders under 15–20 pieces it's almost always the best choice.

For larger orders, these are the methods most used by organisers and their real limitations:

How to collect sizes reliably

For larger orders, these are the methods most used by organisers and their real limitations:

IDProfilo

The most widespread method (about 60% of organisers). Structured data, easy to export. Limitation: typically 15–25% of participants never respond, 10–15% respond late after order closure.

Warning

The convincing number: in a typical group order, 10–20% of garments end up with incorrect sizes post-delivery. Since custom garments are generally non-returnable, this generates a direct cost increase of 10–20% (reorders, logistics, urgent shipping) and measurable dissatisfaction in the group.

Converting between sizing systems

If ordering from international suppliers, the correspondence between systems isn't immediate. The Italian (IT) system is on average tighter than the American (US) and slightly different from the European (EU).

Size	IT Men	EU	US	UK
XS	44	XS (44)	XS	32–34
S	46–48	S (46)	S	36–38
M	48–50	M (48)	M	38–40
L	52–54	L (52)	L	42–44
XL	56–58	XL (54)	XL	46–48
XXL	60	XXL (56)	XXL	50
XXXL	62	3XL	XXXL	52

IT Men

XS (44)

32–34

IT Men

46–48

S (46)

36–38

IT Men

48–50

M (48)

38–40

IT Men

52–54

L (52)

42–44

IT Men

56–58

XL (54)

46–48

XXL

IT Men

XXL (56)

XXL

XXXL

IT Men

3XL

XXXL

Children's sizes — age/height correspondence:

IT Size	Indicative age	Height (cm)
6A	6–7 years	116–122
8A	8–9 years	122–134
10A	10–11 years	134–146
12A	12–13 years	146–158
14A	14–15 years	158–170

Indicative age

6–7 years

Height (cm)

116–122

Indicative age

8–9 years

Height (cm)

122–134

10A

Indicative age

10–11 years

Height (cm)

134–146

12A

Indicative age

12–13 years

Height (cm)

146–158

14A

Indicative age

14–15 years

Height (cm)

158–170

The most common mistakes in group orders

These are the recurring patterns that emerge from data of those working daily with custom apparel orders.

Ordering the same quantity for each size is the surest way to have leftover stock. Never do this.

A "mixed" order that's 70% women has a completely different curve from a balanced one. Always ask for at least an estimate of the mix before closing the order.

If the garment is slim or oversized, participants expect to take a different size. Without this information, responses to size forms produce incomparable data.

XS and XXXL are often excluded to save money, but this leaves out people who actually need them. Better 1–2 pieces than zero.

For orders over 50 pieces, always plan 2–3% extra pieces distributed across central sizes (L and XL). It costs little and almost always solves last-minute problems.

"I'll order size L" means nothing if the brand runs 3cm wider or narrower than usual. The size chart in centimetres is the only reliable reference across different brands.

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Frequently asked questions

For a generic mixed group of adults, size L represents about 30% of the order — so about 30 pieces out of 100. For a corporate group with average age above 40, the share rises to 32–35%. For university students or female athletes, it drops to 17–24%.

Apply your demographic segment's percentages to the total number of pieces, using the largest remainder method for rounding — the only one that guarantees the final sum equals exactly the number of pieces ordered. For a mixed sports group of 50 people (32% M, 28% L, 18% S, 12% XL) you'll get: 16 M, 14 L, 9 S, 6 XL, plus 5 pieces distributed among the extreme sizes.

Size L is the most ordered in almost all adult segments. The exception is the female university segment (M prevails) and the female sports segment (S and M have similar weights). In corporate and senior contexts, XL often becomes the second most important size.

For hoodies, 35% of users prefer to take one size up from their usual measurement. The optimal distribution shifts towards larger sizes. This effect is already incorporated in the Size Finder when you select 'Sweatshirt / Hoodie' as garment type.

Not always. The IT system is on average tighter than American (US) and slightly different from European (EU, based on German-French standard). A size M corresponds to EU 48, US M, UK 38–40 for men. The only truly reliable data are the measurements in centimetres in the specific brand's size chart.

No. For children, sizes are based on height and age, not adult measurements. Standard sizes range from 6A (6–7 years, about 116–122 cm) to 14A (14–15 years, about 158–170 cm). In lower secondary school, some children start using adult sizes XS and S.

Almost always because a uniform distribution was ordered (same quantity for each size) instead of following the demographic segment's statistical curve. Sizes XS and XXXL have very low real demand in most groups — ordering them in quantities equal to central sizes generates structural leftovers.

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