Large Letter Size Envelopes. Sizes range from miniature 3 1/4 square envelopes to calendar size 12 1/2 square envelopes. 4.8 out of 5 stars 8,255.
For mailing contents such as a4 sized documents, dvds, certificates, large greeting cards and magazines you would need to send as a large letter. Large letter cardboard envelopes are perfect for those looking to keep their items well protected whilst keeping at the smaller end of the royal mail postage size scale. The largest standard envelope size to fit within this range is a c4, which measures 324mm x 229mm, fitting nicely under the size limits.
Most square styles have square flaps on the back, but a few have deep triangular contour flaps that nicely offset the square envelope.
Item size 12.5 x 9.5 weight limit 0.5 lb. To qualify as a flat the item must have one dimension that is outside of the maximum for letter and comply with the following maximum dimensions. 130 x 240 x 5mm. Item size 12.5 x 9.5 weight limit 0.5 lb.