Description
Create perfectly fitted envelopes for any paper size using a mathematically consistent model.
This calculator is based on a 45° diagonal projection method, allowing you to generate a square envelope blank from any rectangular insert. Unlike standard Vaessen Creative scoring boards, this approach is not limited to predefined sizes and gives you full control over fit and clearance.
The algorithm:
You define:
- Insert width (
x) - Insert length (
y) - Padding (
z)
The system calculates:
- Required square paper size
- Two scoring distances
Padding (z) controls how tight or loose the envelope fits.
Recommended defaults:
- 10 mm → tight fit
- 15 mm → standard (default)
- 20 mm → loose / bulky inserts
This method is ideal for:
- Non-standard paper sizes (JIS, custom cuts)
- Folded sheets
- Precision crafting
Calculator
Envelope Calculator (Metric)
Enter the finished folded insert size in millimetres.
Use the folded size of the insert, not the original flat sheet size.
Precalculated Values For Folded Sheets
A series
| Paper / Fold | Width (x) in mm | Length (y) in mm | Padding (z) | Square paper size | Score 1 | Score 2 | Rounded cut size | Rounded score marks |
|---|---|---|---|---|---|---|---|---|
| A4 half-fold (A5) | 210 | 148.5 | 10 mm | 273.5 mm × 273.5 mm | 158.5 mm | 115.0 mm | 273 mm × 273 mm | 158 mm and 115 mm |
| A4 half-fold (A5) | 210 | 148.5 | 15 mm | 283.5 mm × 283.5 mm | 163.5 mm | 120.0 mm | 283 mm × 283 mm | 163 mm and 120 mm |
| A4 half-fold (A5) | 210 | 148.5 | 20 mm | 293.5 mm × 293.5 mm | 168.5 mm | 125.0 mm | 293 mm × 293 mm | 168 mm and 125 mm |
| A4 tri-fold | 210 | 99 | 10 mm | 238.5 mm × 238.5 mm | 158.5 mm | 80.0 mm | 238 mm × 238 mm | 158 mm and 80 mm |
| A4 tri-fold | 210 | 99 | 15 mm | 248.5 mm × 248.5 mm | 163.5 mm | 85.0 mm | 248 mm × 248 mm | 163 mm and 85 mm |
| A4 tri-fold | 210 | 99 | 20 mm | 258.5 mm × 258.5 mm | 168.5 mm | 90.0 mm | 258 mm × 258 mm | 168 mm and 90 mm |
| A5 half-fold (A6) | 148 | 105 | 10 mm | 198.9 mm × 198.9 mm | 114.7 mm | 84.2 mm | 199 mm × 199 mm | 115 mm and 84 mm |
| A5 half-fold (A6) | 148 | 105 | 15 mm | 208.9 mm × 208.9 mm | 119.7 mm | 89.2 mm | 209 mm × 209 mm | 120 mm and 89 mm |
| A5 half-fold (A6) | 148 | 105 | 20 mm | 218.9 mm × 218.9 mm | 124.7 mm | 94.2 mm | 219 mm × 219 mm | 125 mm and 94 mm |
| A6 half-fold (A7) | 105 | 74 | 10 mm | 146.6 mm × 146.6 mm | 84.2 mm | 62.3 mm | 147 mm × 147 mm | 84 mm and 62 mm |
| A6 half-fold (A7) | 105 | 74 | 15 mm | 156.6 mm × 156.6 mm | 89.2 mm | 67.3 mm | 157 mm × 157 mm | 89 mm and 67 mm |
| A6 half-fold (A7) | 105 | 74 | 20 mm | 166.6 mm × 166.6 mm | 94.2 mm | 72.3 mm | 167 mm × 167 mm | 94 mm and 72 mm |
B series — ISO
| Paper / Fold | Width (x) in mm | Length (y) in mm | Padding (z) | Square paper size | Score 1 | Score 2 | Rounded cut size | Rounded score marks |
|---|---|---|---|---|---|---|---|---|
| B5 ISO half-fold (B6) | 176 | 125 | 10 mm | 232.8 mm × 232.8 mm | 134.5 mm | 98.4 mm | 233 mm × 233 mm | 134 mm and 98 mm |
| B5 ISO half-fold (B6) | 176 | 125 | 15 mm | 242.8 mm × 242.8 mm | 139.5 mm | 103.4 mm | 243 mm × 243 mm | 139 mm and 103 mm |
| B5 ISO half-fold (B6) | 176 | 125 | 20 mm | 252.8 mm × 252.8 mm | 144.5 mm | 108.4 mm | 253 mm × 253 mm | 144 mm and 108 mm |
| B6 ISO half-fold (B7) | 125 | 88 | 10 mm | 170.6 mm × 170.6 mm | 98.4 mm | 72.2 mm | 171 mm × 171 mm | 98 mm and 72 mm |
| B6 ISO half-fold (B7) | 125 | 88 | 15 mm | 180.6 mm × 180.6 mm | 103.4 mm | 77.2 mm | 181 mm × 181 mm | 103 mm and 77 mm |
| B6 ISO half-fold (B7) | 125 | 88 | 20 mm | 190.6 mm × 190.6 mm | 108.4 mm | 82.2 mm | 191 mm × 191 mm | 108 mm and 82 mm |
B series — JIS
| Paper / Fold | Width (x) in mm | Length (y) in mm | Padding (z) | Square paper size | Score 1 | Score 2 | Rounded cut size | Rounded score marks |
|---|---|---|---|---|---|---|---|---|
| B5 JIS half-fold (B6) | 182 | 128.5 | 10 mm | 239.6 mm × 239.6 mm | 138.7 mm | 100.9 mm | 240 mm × 240 mm | 139 mm and 101 mm |
| B5 JIS half-fold (B6) | 182 | 128.5 | 15 mm | 249.6 mm × 249.6 mm | 143.7 mm | 105.9 mm | 250 mm × 250 mm | 144 mm and 106 mm |
| B5 JIS half-fold (B6) | 182 | 128.5 | 20 mm | 259.6 mm × 259.6 mm | 148.7 mm | 110.9 mm | 260 mm × 260 mm | 149 mm and 111 mm |
| B6 JIS half-fold (B7) | 128 | 91 | 10 mm | 174.9 mm × 174.9 mm | 100.5 mm | 74.3 mm | 175 mm × 175 mm | 101 mm and 74 mm |
| B6 JIS half-fold (B7) | 128 | 91 | 15 mm | 184.9 mm × 184.9 mm | 105.5 mm | 79.3 mm | 185 mm × 185 mm | 106 mm and 79 mm |
| B6 JIS half-fold (B7) | 128 | 91 | 20 mm | 194.9 mm × 194.9 mm | 110.5 mm | 84.3 mm | 195 mm × 195 mm | 111 mm and 84 mm |
How to Make a Custom Envelope for JIS B5 Folded in Half
Finished insert size
A JIS B5 sheet is 182 mm × 257 mm. Folded in half, the insert becomes:
182 mm × 128.5 mm
Using 15 mm padding, the calculator gives:
| Measurement | Exact | Practical (Rounded) |
|---|---|---|
| Square paper size | 249.6 mm × 249.6 mm | 250 mm × 250 mm |
| Score 1 | 143.7 mm | 144 mm |
| Score 2 | 105.9 mm | 106 mm |
Tools and materials
You will need:
- One JIS B4 donor sheet
- One JIS B5 sheet folded in half
- Paper cutter
- Vaessen Creative Score Easy scoring board
- Diagonal scoring guide
- Folding knife or bone folder
- Vaessen Creative Corner Punch
- Optional 10 mm Corner Punch
- Paper glue
Practical reference
For a JIS B5 sheet folded in half with 15 mm padding, use:
Cut size: 250 mm × 250 mm
Score marks: 144 mm and 106 mm
Score pattern: 144 → 106 → 144 → 106
Step 1: Prepare the workspace
Set out the paper cutter, scoring board, diagonal guide, folding tool, punch, glue and paper.
Step 2: Cut the donor sheet
Start with a JIS B4 donor sheet.
Cut it to:
250 mm × 250 mm
The calculated size is 249.6 mm, so 250 mm is the practical cut size.
Step 3: Set up the scoring board
Place the diagonal scoring guide into the Vaessen Creative Score Easy board.
Step 4: Make the first score
Place the square sheet on the scoring board with one corner aligned to the diagonal guide.
Score at:
144 mm
Step 5: Rotate and make the second score
Rotate the paper 90 degrees.
Score at:
106 mm
Step 6: Complete all four score lines
Continue rotating the paper and alternate the score marks:
144 mm → 106 mm → 144 mm → 106 mm
When finished, the sheet should have four score lines.
Step 7: Check the score pattern
The score lines should form an X-style structure where the folds meet.
Step 8: Punch out the corners
Use the corner punch to remove the small corner sections where the folds meet. This reduces bulk and helps the envelope fold cleanly.
Step 9: Test the insert fit
Place the folded JIS B5 sheet into the future envelope before gluing. Confirm that it fits comfortably.
Step 10: Optional: round the flap corner
Use a 10 mm Corner Punch if you want a cleaner finished flap.
Step 11: Fold the envelope
Fold along all score lines. Bring the side flaps inward first, then fold the bottom flap up.
Step 12: Apply glue
Apply a small amount of glue to the smaller side flap or overlap area. Avoid using too much glue.
Step 13: Press the glued flap
Fold the glued flap into place and press firmly. Let the glue set.
Step 14: Insert the folded sheet
Place the folded JIS B5 sheet into the finished envelope.
Step 15: Close the final flap
Fold the top flap down to close the envelope.
Step 16: Finished envelope
The finished envelope should fit the folded JIS B5 insert neatly with 15 mm padding.
Step 17: Store the tools
Store the diagonal guide and folding knife in the back of the Score Easy board.
