Stamp Size Guide: Choosing the Right Dimensions
Choosing the right stamp size is the difference between a crisp, professional impression and a smudged, unreadable one. A seal that is too small will crowd its text and clog with ink; one that is too large wastes space on the page and can feel heavy-handed. This guide walks through the standard dimensions used for round seals, rectangular address and date stamps, and official notary and company seals, so you can pick a size that fits both your content and the surface you are stamping.
Why size matters before you design
The physical footprint of a stamp sets a hard limit on how much text and how much detail can survive the transfer from die to paper. Rubber and polymer stamps lose fine detail at the edges, and every extra line of text shrinks the height available for each character. It is far easier to decide on dimensions first and design within them than to shrink a finished layout until it becomes illegible. In the Stampzio editor you can set your canvas to the exact target size early, so what you see on screen matches the millimetres you will order.
Common stamp sizes and their uses
The table below lists widely used sizes across the main stamp categories. Millimetre values are the practical standard in most of the world; inch equivalents are rounded to help readers using imperial measurements.
| Stamp type | Typical size | Approx. inches | Common use |
|---|---|---|---|
| Small round seal | 30 mm diameter | 1.18 in | Monograms, simple logos, "approved" marks |
| Standard round seal | 38–40 mm diameter | 1.5–1.57 in | Company seals, club and association emblems |
| Large round seal | 45–50 mm diameter | 1.77–1.97 in | Official seals with an inner emblem and two text rings |
| Notary seal (round) | 38–42 mm diameter | 1.5–1.65 in | Notarial acknowledgements (check your local rules) |
| Notary seal (rectangular) | 25 × 58 mm | 1 × 2.3 in | Jurisdictions that mandate a rectangular format |
| Small rectangular stamp | 14 × 38 mm | 0.55 × 1.5 in | Signature lines, short date stamps, initials |
| Address stamp | 25 × 55 mm | 1 × 2.17 in | Return addresses, three to five lines of text |
| Large rectangular stamp | 30 × 70 mm | 1.18 × 2.76 in | Business stamps with logo, address and registration number |
How much text actually fits
A reliable rule of thumb is that legible stamp text needs roughly 3 mm of character height at minimum, and 4–5 mm reads comfortably. Working backwards from the stamp height tells you how many lines you can realistically include.
- 14 mm tall: one to two lines, or a single bold line plus a thin rule.
- 25 mm tall: three to four lines of address-style text.
- 30 mm tall: four to five lines, or a small logo beside three lines.
For round seals, remember that curved text along the rim takes up circumference, not height. A 38 mm circle comfortably holds one outer ring of text and a short inner line or emblem; a 50 mm circle can carry two curved rings (top and bottom) plus a central graphic. Padding of at least 2–3 mm between the outer border and the text keeps letters from touching the frame after ink spread.
Tip: If a design feels cramped, cut words before you cut point size. "Ltd." instead of "Limited", or a postcode on its own line, buys back legibility without shrinking the type.
Legibility factors beyond size
- Stroke weight: hairline serifs and ultra-thin fonts break up at small sizes. Choose medium or bold weights for anything under 30 mm.
- Letter spacing: add a little tracking so ink does not bridge the gaps between characters.
- Contrast of elements: avoid packing a detailed logo, a border, and dense text into a small round seal — pick two of the three.
- Border thickness: scale the frame with the stamp. A 1 mm border suits a small seal; a large official seal can carry a double ring.
Exporting at the right resolution
Manufacturers typically ask for artwork at 300 to 600 DPI at the final physical size, and many prefer vector files that stay sharp at any scale. To convert millimetres to pixels for a raster export, use: pixels = (millimetres ÷ 25.4) × DPI.
- A 40 mm round seal at 600 DPI ≈ 945 × 945 px.
- A 25 × 55 mm address stamp at 600 DPI ≈ 591 × 1299 px.
- The same address stamp at 300 DPI ≈ 295 × 650 px — acceptable, but 600 DPI keeps thin lines crisp.
Whenever possible, export a vector SVG from the Stampzio editor: it carries no fixed resolution and can be resized without any loss, which is ideal for a stamp maker who may enlarge or shrink your die. If you need a raster file, export a transparent PNG at 600 DPI for the target dimensions so the background does not print as a solid block. Keeping your artwork monochrome (pure black on transparent) also matches how most rubber and self-inking stamps are produced.
Quick checklist before you order
- Confirm the physical size in millimetres and set the canvas to match.
- Keep body text at 3 mm or taller; reduce line count if needed.
- Leave 2–3 mm padding inside borders and around curved text.
- Use medium or bold fonts and a touch of letter spacing.
- Export SVG where accepted, or a transparent PNG at 600 DPI.
Get the dimensions right at the start and every downstream decision — font choice, line count, border weight and export settings — falls into place. A stamp built to a known size prints cleanly the first time and stays readable for thousands of impressions.