A 165 × 165mm envelope is a lovely choice for square stationery and is specifically designed to fit:
155 × 155mm inserts
Square invitations
6 inch style cards
Wedding invitations
Save the dates
RSVP details cards
Birthday cards
Thank you cards
Handmade greeting cards
Luxury stationery sets
Small prints or keepsake cards
Choosing the right envelope size helps your square cards and inserts sit neatly inside without feeling too tight. A 165 × 165mm envelope gives your stationery a clean, balanced finish while helping to keep your cards protected and beautifully presented.