When choosing numbers for printing, the main thing is to increase the numbers for the extreme sizes proportionally more than ones in the middle (since the true distribution of human sizes is somewhat wider than the distribution of our t-shirt sizes), and to increase the numbers for unpopular-in-penta sizes proportionally more than for the most popular, in case they turn out to be more popular when people see the real sizes of the shirts. In both cases the *absolute* number added to the penta requests may be lower than for the most popular sizes. Due to the smaller overall numbers for women's shirts, the proportional increase will be higher there, but again with fairly low absolute numbers added.
Also remember to add extra t-shirts (and bags, if applicable) for all sponsors (one per sponsor bag, including permanent infrastructure sponsors). Normally we add these to the count for "male large" shirts.
Sometimes we ran out of the smaller sizes (male S, female M and S) quite quickly. That was partly due to demand for them from additional female local volunteers (of whom there have often been comparatively many), but also from male attendees who found that the S or M shirts were bigger than they expected and wanted to switch to XS or S. (The DebConf13 t-shirt page below contains detailed information on how many were ordered that year, where again we quickly ran out of women's shirts and small men's sizes, despite having increased those numbers in advance.)
Of course, this could all be more efficient if we determined in advance what shirts we will use and their true sizes, before people chose their type, but in practice what what each size name means in a particular year is something of a lottery.... Fortunately attendees are happy to take any spare shirts (within reason), and we have also had success with selling surplus ones towards the end of the conference.
Ideally we would increase the numbers of staff t-shirts enough so that volunteers doing the most visible jobs can wear a staff t-shirt every day that they are working.
Our most successful printing (high quality and low cost) has been through our Mexican t-shirt printer. There we have previously used Yazbek D0300 women's t-shirts and C0300 men's t-shirts. Both use 200 g/m² material. We have used colours from the more limited range available for the women's shirts, so that the colours of men's and women's shirts match.
- DebConf11 numbers: DebConf11/T-Shirts#Decisions
- DebConf12 numbers: DebConf12/T-Shirts#Numbers
- DebConf13 numbers: DebConf13/T-shirts#Numbers
- DebConf14 numbers: DebConf14/T-shirts#Numbers
- DebConf15 numbers: DebConf15/T-shirts#Numbers
- History of T-shirt_colors