Quick answer: A DL envelope measures 110 × 220 mm, approximately 4.33 × 8.66 inches. It is designed to hold an A4 sheet folded into thirds, making it a common choice for business letters, invoices and direct mail.
Measurement note: dimensions are stated width × height in portrait orientation. Turn the sheet through 90 degrees for landscape use. Millimetres are the controlling values for ISO sizes; inch figures are rounded conversions.
DL envelope dimensions
| Unit | Width | Height |
|---|---|---|
| Millimetres | 110 mm | 220 mm |
| Centimetres | 11 cm | 22 cm |
| Inches | 4.33 in | 8.66 in |
| Area | 24,200 mm² | 0.0242 m² |
How to fold A4 for a DL envelope
A4 is 210 × 297 mm. Fold the 297 mm dimension into three panels of about 99 mm each, leaving a finished folded piece around 99 × 210 mm. The 110 × 220 mm envelope then provides practical clearance.
- Place the A4 sheet portrait with the printed side facing down if using a standard letter fold.
- Bring the lower third upward.
- Bring the upper third downward over it.
- Check that any address block aligns with the envelope window before creasing fully.
Production folding machines may use a roll fold, Z-fold or other sequence. The panel widths are sometimes made slightly unequal so the inner panel nests without buckling.
DL versus C5 and C6
| Envelope | Dimensions | Typical A4 preparation |
|---|---|---|
| DL | 110 × 220 mm | Fold into thirds |
| C5 | 162 × 229 mm | Fold once to A5 |
| C6 | 114 × 162 mm | Fold twice to A6 |
Designing a letter for a window DL envelope
Obtain the exact envelope template because window size and position vary. Print a test, fold it exactly as it will be processed and check that only the intended address is visible. Keep confidential text outside the window area and allow for movement inside the envelope.
Postal and fulfilment considerations
DL usually falls within ordinary letter categories, but postage depends on the completed item’s weight, thickness and destination. Inserts, return envelopes and promotional cards can increase thickness. Automated inserting also requires consistent folds, paper grain and static control.
Frequently asked questions
What does DL stand for?
The designation is widely associated with “dimension lengthwise”, though the practical point is the recognised 110 × 220 mm format.
Can A5 fit in DL?
A5 at 148 × 210 mm does not fit flat because it is wider than the 110 mm envelope. It can fit only if folded again.
Is DL the same as a US #10 envelope?
No. They are similar business-envelope formats but have different dimensions. A US #10 envelope is commonly 4.125 × 9.5 inches.
Test the complete mailed item
Postal success for DL Envelope Size Explained depends on the assembled item, not the nominal paper size. Build a dummy using the intended card, folds, inserts, adhesive and envelope. Weigh it, measure its maximum thickness without compressing it, and check whether embellishments create rigid or uneven areas. A piece that fits while empty may bow, split a seam or move into another price category once assembled.
Before producing a campaign quantity of DL Envelope Size Explained, take the finished dummy to the postal operator or mailing house. Bulk services can impose rules for address position, clear zones, barcodes, return addresses, tabs and machinability that do not apply to a single handwritten item.
Content and accessibility checks
On DL Envelope Size Explained, use a clear hierarchy for the recipient name, date, address, response deadline or call to action. Avoid placing essential information over folds, textured backgrounds or metallic finishes. Address panels should have strong contrast. A QR code should supplement, not replace, a readable URL or essential instruction; test it on the final printed stock under ordinary indoor light.
How to specify the size without ambiguity
For DL Envelope Size Explained, a reliable print specification states more than the familiar format name. Give the finished width and height, measurement unit, orientation, number of pages or panels, paper weight, surface, colour process, bleed, finishing and quantity. This prevents regional names and printer defaults from silently changing this particular job.
- Finished size: write width × height and identify portrait or landscape.
- Artwork size: distinguish the trimmed page from any larger bleed canvas or parent sheet.
- Stock: specify grammage or basis weight, coating, colour and recycled or certified requirements.
- Finishing: state folds, scoring, binding, drilling, corner rounding, lamination or mounting.
- Tolerance: ask the supplier what cutting, folding and registration variation should be expected.
When ordering DL Envelope Size Explained, a short name alone leaves important decisions unstated. A specification such as “finished size as stated above; portrait; 3 mm bleed; 170 gsm uncoated white stock; full colour both sides; scored where shown” is harder to misinterpret. When the format has regional variants, include the governing standard or exact dimensions every time.
Make a full-size physical proof
Screens do not communicate the physical scale of DL Envelope Size Explained reliably. Before a large order, print a representative page at 100%, trim it to the stated size and use it as the finished item will be used. Measure one horizontal and one vertical feature with a ruler. Fold it, place it in its envelope or holder where relevant, view it from the intended distance and ask someone unfamiliar with the design to find the main information.
A proof of DL Envelope Size Explained should check more than spelling. Look for text that is technically present but difficult to read, lines that sit too close to the trim, images whose important details enter a fold or binding area, barcodes or QR codes that do not scan, and stocks that crack or show through. For colour-critical work, a calibrated contract proof or press proof is more informative than an office print.
Sources and standards
The measurements and production guidance in this guide were checked against the following standards bodies, postal operators and print-platform specifications. Standards can be revised or withdrawn, so check the linked record when a contractual or regulated specification matters.