Envelope sizes
A #10 envelope is 4 1/8 × 9 1/2 in (104.8 × 241.3 mm) and holds a Letter sheet folded in thirds. DL (110 × 220 mm) does the same for A4.
Measurements
| Envelope | Width | Length | Holds |
|---|---|---|---|
| #10 envelope | 4.13 in10.5 cm | 9.5 in24.1 cm | Standard U.S. business letter, fits Letter folded in thirds |
| #9 envelope | 3.88 in9.8 cm | 8.88 in22.5 cm | Reply envelope that fits inside a #10 |
| A7 envelope | 5.25 in13.3 cm | 7.25 in18.4 cm | Invitations and 5 × 7 cards |
| DL envelope | 4.33 in11 cm | 8.66 in22 cm | A4 folded in thirds (ISO 269) |
| C6 envelope | 4.49 in11.4 cm | 6.38 in16.2 cm | A4 folded twice (A6) |
| C5 envelope | 6.38 in16.2 cm | 9.02 in22.9 cm | A4 folded once (A5) |
| C4 envelope | 9.02 in22.9 cm | 12.76 in32.4 cm | A4 unfolded |
Questions people ask
What envelope fits a Letter sheet folded in thirds?
A #10 envelope (4 1/8 × 9 1/2 in).
Related sizes
Sources and method
- ISO 269 envelope sizes
- U.S. commercial envelope sizes
Imperial and metric values are converted with 1 in = 25.4 mm exactly and rounded only for display. Found a mistake? Report it and we will correct the page.