The tri-fold (letter fold) is the global gold standard for executive correspondence, invoices, legal notices, and formal letters. It divides US Letter or A4 paper into three equal panels.
Ideal for formal business mailings, invoices, cover letters, and documents sent inside standard #10 business envelopes or DL envelopes.
USPS #10 (4.125 × 9.5 in) • ISO DL (110 × 220 mm)
When sending mail in window envelopes, standard tri-folds conceal recipient addresses. The Z-fold creates an alternating accordion pattern that places the address block directly against the transparent window.
Required for billing statements, payroll checks, official government notices, and automated window envelope insertion.
Match your sheet dimensions to standard commercial envelopes to prevent postage delays and bulky mailings.
Answers to common stationery, business mailing, and postal envelope folding questions.
The classic 3-panel fold designed specifically for standard #10 business envelopes. The tri-fold (letter fold) is the global gold standard for executive correspondence, invoices, legal notices, and formal letters. It divides US Letter or A4 paper into three equal panels.