The two business envelope sizes are DL, 110 × 220 mm, which takes an A4 letter folded in three, and C5, 162 × 229 mm, which takes an A4 letter folded once or A5 sheets flat. Both come window or plain, gummed or self-seal. Cards use their own sizes: an A6 card goes into a C6 envelope at 114 × 162 mm.
This guide is about choosing and printing the envelope itself: size, window, print area and quantity. For fitting a complete set together, including folders and inserts, read our guide to letterhead, envelope and folder compatibility.
What envelope sizes are used for business printing in Singapore?
DL at 110 × 220 mm is the standard business envelope, and C5 at 162 × 229 mm is the larger one for a letter folded once. Card envelopes follow the card: C6 at 114 × 162 mm for an A6 card, and 130 × 181 mm for the 127 × 178 mm invitation card. A square card needs a square envelope, so confirm one exists first.
| Envelope | Size | What goes in it | Typical use |
|---|---|---|---|
| DL | 110 × 220 mm | An A4 letter folded in three, or a DL slip or flyer flat | Letters and compliment slips |
| C5 | 162 × 229 mm | An A4 letter folded once, or A5 documents flat | Letters folded once, A5 documents |
| C6 | 114 × 162 mm | An A6 card at 105 × 148 mm | Detail cards, compact invitations |
| Invitation | 130 × 181 mm | A 127 × 178 mm card, five by seven inches | Invitations |
| Square | Matched to the card | A 148 × 148 mm square card | Distinctive cards; confirm the envelope first |
| Lead time | All of the above | Standard 7–14 working days | Printed envelopes included |
Size the envelope from the document, not the other way round. A stationery set is a system: each piece has a job and a size that follows from the envelope it goes into, which is why the envelope is usually where the decisions start.
Which envelope fits an A4 letter?
It depends on the fold. An A4 letter at 210 × 297 mm folded twice into thirds goes into a DL envelope, and the same letter folded once goes into a C5. A letter that must arrive unfolded needs a larger envelope, usually called C4, which is not one of the two sizes listed for the stationery service, so raise it in the quote request.
The DL route is the everyday one. A third of an A4 sheet is 99 × 210 mm, the DL size, so a compliment slip, a DL flyer and a letter folded in three all go into the same 110 × 220 mm envelope. DL, one third of A4, is the standard rack and envelope size in Singapore.
C5 suits a letter that should not be creased twice, and documents already at A5, 148 × 210 mm, which go in flat. Choose the fold before the envelope: the same A4 letter needs a different envelope, and a different address-block position, depending on whether it is folded once or twice.
Where does the window go on a DL window envelope?
The standard DL window is 45 × 90 mm, set 20 mm from the left edge and 15 mm from the bottom of the envelope. Position the address block on the letterhead against that window with 5 mm of tolerance on every side, because a folded letter shifts slightly inside the envelope as it travels.
An address block that does not line up with the window is usually discovered when the first thousand letters are folded, and the fix is a reprint of either the letter or the envelope. Two habits prevent it:
- Design to the window, not the grid. Place the address block where the window falls after folding, rather than where it looks balanced on the page.
- Send the envelope type with the letterhead file. The address block is then checked against the actual window position before either piece is printed.
A plain envelope has no window to align with, so the address is printed, labelled or written on the face. Choose window envelopes where the letter is generated with an address block, and plain envelopes where the envelope itself carries the address.
What can be printed on an envelope?
Envelopes are printed on the face and, where asked, on the flap. Ink is kept clear of the gum line, because gum will not take ink and ink over gum stops the envelope sealing. Full-bleed printing is avoided: an envelope has seams and a gum line, and neither takes ink evenly.
Envelopes are bought as made envelopes and then printed, rather than cut from a sheet, so the print area is set by the construction. In practice:
- Face: the logo and return address, kept clear of the seams.
- Flap: an optional return address or mark, clear of the gum line.
- Colour: spot colours for a one or two colour identity; CMYK only where a photograph is involved.
- Small text: K100, 7 pt minimum on uncoated and laid stock.
- Fonts: outlined or fully embedded in a PDF/X-4 file.
The envelope stock itself is a choice between a smooth wove and a laid finish, matched to the letterhead. A laid finish carries fine parallel ribs, and type sits crisply on them while a large solid shows the ribbing as a faint stripe, which is another reason to keep envelope artwork to type and marks rather than solid areas.
How do you match envelopes to a letterhead?
Order them together on matched stock. Paper whites shift between batches, so a letterhead and an envelope bought six months apart are visibly different shades on a desk. A matched set is quoted as one job because the stock has to be common to all of it: one order, one white, one identity.
The letterhead in a set is A4 on 100–120 gsm uncoated woodfree or laid text, with a 10 mm clear margin all round so an office laser printer can grip the sheet. Compliment slips are DL 99 × 210 mm on the same stock as the letterhead, which is also why they slide flat into the DL envelope. The envelope is then chosen in wove or laid to match.
For the choice of letterhead paper itself, see our guide to corporate letterhead paper. The point for envelopes is simpler: decide the finish once, and order every piece of the set against it.
How many envelopes can be ordered, and how long does it take?
The minimum run is 100 for letterheads and envelopes. Standard turnaround is 7–14 working days for the whole set, printed envelopes included, and express is quoted per job. What sets the date is the pieces that are not sheets: envelopes are made envelopes ordered as stock and then printed.
A reorder is simpler than the first order. A stationery set reorders as the same specification against the same held stocks, and the checked window position on the envelope is kept, along with any foil block or embossing die for the set. If the date is tight, say which pieces, which stock, how many colours and whether the envelopes have windows, and ask for an express quotation. Delivery is by island-wide courier, and collection is by arrangement.
Worked example: how would a letterhead and DL envelope set be specified?
An organisation sends printed letters that are folded in three and posted in window envelopes. The specification below pairs a laid letterhead with DL window envelopes, prints two colours on both, and positions the letterhead address block to the standard window so the two pieces are checked against each other before printing.
Hypothetical planning example. Actual production timing, paper availability, and logistics are confirmed individually upon artwork and specification review.
- Quantity: 1,000 A4 letterheads and 1,000 DL envelopes.
- Letterhead: 100 gsm laid text, 2C printed, one Pantone plus black, with a 10 mm clear margin all round.
- Envelope: DL window envelope, 110 × 220 mm, laid finish to match, printed on the face only.
- Window: the address block on the letterhead positioned to the standard 45 × 90 mm window, 20 mm from the left and 15 mm from the bottom, with 5 mm of tolerance.
- File: print-ready PDF, with the envelope type sent alongside the letterhead file.
- Date: counted back from the upper end of the standard 7–14 working day window.
Later, the organisation adds a C5 envelope for longer letters folded once. Because the set is held as one specification, the C5 is ordered on the same laid finish so the white still matches.
Frequently asked questions
What size envelope fits an A4 letter?
A DL envelope at 110 × 220 mm takes an A4 letter folded in three, and a C5 envelope at 162 × 229 mm takes it folded once. A letter that must stay flat needs a larger envelope, which should be raised in the quote request.
What size is a DL envelope?
A DL envelope is 110 × 220 mm. It takes an A4 letter folded in three, or a DL compliment slip or flyer at 99 × 210 mm flat, and it is the standard business envelope.
Where is the window on a DL envelope?
The standard window is 45 × 90 mm, 20 mm from the left edge and 15 mm from the bottom. Position the address block against it with 5 mm of tolerance, because the folded letter moves slightly inside the envelope.
Can you print on the envelope flap?
Yes, on the face and on the flap, but the ink is kept clear of the gum line, because gum will not take ink and ink over gum stops the envelope sealing. Full-bleed envelope printing is avoided because the seams print unevenly.
What envelope fits an A6 card?
A C6 envelope at 114 × 162 mm fits an A6 card at 105 × 148 mm. Invitation cards at 127 × 178 mm use a 130 × 181 mm envelope, and a square card needs a square envelope.
How do you order envelope printing from EZ Print?
EZ Print prints envelopes, letterheads and compliment slips in Singapore, and has traded since 2017. Every job is quoted from its specification: send the envelope size, window or plain, gummed or self-seal, the number of colours and the matching letterhead stock. Standard turnaround is 7–14 working days, and express is quoted per job.
See the full specification on our business stationery printing page. For card envelopes, see invitation printing and postcard printing. When the specification is ready, request a quote with the pieces and quantities you need.
Same-day and urgent printing available. Subject to artwork approval, payment, print type and production availability. Timing confirmed per job.