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The Ultimate Guide to Fountain Pen Friendly Paper: Sizes vs Sizing, Weights & GSM
- provincialmills
- Jan 2
- 10 min read
Updated: Jan 3
If you’ve ever filled your favorite fountain pen with a beautiful shimmering ink only to have it "feather" across the page like a piece of paper towel, you know the frustration. Not all paper is created equal—especially for calligraphers and pen enthusiasts.
Understanding paper sizes and weights is the secret to finding the perfect journal or stationery. Whether you are trying to find a refill for a leather cover or looking for fountain pen friendly paper that won't bleed, this guide has you covered.
Understanding Paper Sizes
What size is an A5 notebook in inches?
One of the most common questions we get is: "What size is an A5 notebook in inches?" The answer is 5.8 x 8.3 inches. This makes it the perfect "middle ground" size—large enough for sprawling calligraphy flourishes, but small enough to toss in a bag.
But there is more to know than just the A5.........
Decoding International Sizes (The ISO 216 Standard)
Most of the fountain pen world (like Rhodia, Clairefontaine, and Tomoe River) follows the ISO (International Organization for Standardization) system.
The "A" series is the most common. The magic of this system is that each size is exactly half the size of the one before it.
Name | Inches | Centimeters | Typical Use Case |
A0 | 33.1 x 46.8 | 84.1 x 118.9 | Technical drawings, maps, large posters. |
A1 | 23.4 x 33.1 | 59.4 x 84.1 | Blueprints, flipcharts, signage. |
A2 | 16.5 x 23.4 | 42.0 x 59.4 | Fine art prints, calendars, diagrams. |
A3 | 11.7 x 16.5 | 29.7 x 42.0 | Menus, floor plans, large magazines. |
A4 | 8.3 x 11.7 | 21.0 x 29.7 | Global Standard: Letters, resumes, forms. |
A5 | 5.8 x 8.3 | 14.8 x 21.0 | Notebooks, flyers, journals. |
A6 | 4.1 x 5.8 | 10.5 x 14.8 | Postcards, pocket diaries. |
A7 | 2.9 x 4.1 | 7.4 x 10.5 | Large price tags, flashcards. |
A8 | 2.0 x 2.9 | 5.2 x 7.4 | Business cards, tickets. |
A9 | 1.5 x 2.0 | 3.7 x 5.2 | Labels, small coupons. |
A10 | 1.0 x 1.5 | 2.6 x 3.7 | Stamps, tiny stickers, jewelry tags. |
The Calligrapher's Rule of Thumb: In the ISO world, as the number gets higher, the paper gets smaller. (A6 is a postcard; A0 is a poster!)
A Note on the "B" and "C" Series
There are also "sibling" sizes used in Europe:
B Series: Slightly larger than A. If A4 is for the letter, B4 is often used for the posters or books that need to be just a bit bigger.
C Series: Specifically for envelopes. A C4 envelope is designed to fit an A4 sheet of paper perfectly without folding it. So the trick to envelopes is to remember the ratio of ISO paper. If A4 fits into C4 without folding then A4 will fit into C5 envelope after being folded in half!
Artist’s Sidebar: The Magic of the ISO Ratio
Why should a calligrapher care about the International Organization for Standardization (ISO)? Because they gave us a "magic" mathematical constant: 1 : 1.414 (the square root of 2).
Every "A" series paper size uses this exact ratio. For artists, this is a superpower. It means:
Perfect Scaling: You can take a calligraphy layout you designed on A5 and photocopy it up to A4 or A3 without ever changing your margins. The proportions stay identical, so your flourish won't suddenly look "squashed" or "stretched."
Zero Waste: Because each size is exactly half of the one before it, you can buy a large sheet of high-quality A3 calligraphy paper and cut it perfectly into two A4 sheets or four A5 sheets with zero scrap paper left over.
Journal Harmony: If you use an A5 journal, you know that an A4 letter folded exactly in half will fit inside like it was custom-made for it.
The North American System
The US, Canada, and parts of Mexico use sizes based on traditional imperial measurements. These don't follow a perfect mathematical ratio, which is why shrinking a "Legal" document to "Letter" often looks awkward.
Name | Inches | Centimeters | Typical Use Case |
Letter* | 8.5 x 11.0 | 21.6 x 27.9 | Reports, school papers. |
Legal* | 8.5 x 14.0 | 21.6 x 35.6 | Contracts, legal documents. |
Tabloid | 11.0 x 17.0 | 27.9 x 43.2 | Posters, newsletters (vertical), menus. |
Executive | 7.25 x 10.5 | 18.4 x 26.7 | Formal stationery, corporate notepads/letterheads. |
Half Letter* | 5.5 x 8.5 | 14.0 x 21.6 | Personal notepads, small booklets. |
Junior Legal | 5.0 x 8.0 | 12.7 x 20.3 | Yellow legal pads, checklists. |
*Tip: If you are buying a vintage American journal or printing your own calligraphy practice sheets, these are the names you'll see!
Engineering & Architecture (ANSI vs. ARCH)
For the pros building houses and bridges, standard office paper isn't enough. They use the ANSI and ARCH series.
Name | Inches | Centimeters | Typical Use Case |
ANSI C | 17 x 22 | 43.2 x 55.9 | Engineering drawings (C-size). |
ANSI D | 22 x 34 | 55.9 x 86.4 | Standard engineering blueprints. |
ANSI E | 34 x 44 | 86.4 x 111.8 | Master engineering plans. |
ARCH A | 9 x 12 | 22.9 x 30.5 | Small architectural sketches. |
ARCH B | 12 x 18 | 30.5 x 45.7 | Construction "half-size" sets. |
ARCH C | 18 x 24 | 45.7 x 61.0 | Residential construction plans. |
ARCH D | 24 x 36 | 61.0 x 91.4 | Standard Blueprint size for buildings. |
ARCH E | 36 x 48 | 91.4 x 121.9 | Large-scale site plans. |
*Note: In standardized fields where precision is extremely important we can see the same importance for proportions in scaling, similar to what we observed in the ISO model.
US vs. European Paper Sizes:
Which one do you need?
If you have international (ISO)..... | The closest US/North American cousin is... | Comparison Notes |
A3 (11.7" x 16.5") | Tabloid (11.0" x 17.0") | Tabloid is slightly narrower and longer. Often used interchangeably for small posters. |
A4 (8.3" x 11.7") | Letter (8.5" x 11.0") | The most common mismatch. A4 is narrower and taller. A4 documents often get the bottom cut off when printed on US Letter. |
A5 (5.8" x 8.3") | Half Letter (5.5" x 8.5") | Very close! This is the standard "small notebook" or "planner" size in both regions. |
A8 (2.0" x 2.9") | Business Card (2.0" x 3.5") | A8 is much shorter. US business cards are longer and thinner than the ISO standard. |
DL Envelope (4.3" x 8.6") | #10 Envelope (4.1" x 9.5") | The DL (Dimension Lengthwise) is the European standard for a 1/3 folded A4. The US #10 is longer. |
The "Journal Refill" Compatibility Guide
Fountain Pen Enthusiasts often struggle to find refills for their leather covers which were made to take either ISO or North American size refills. Use this table to help them find the right fit:
If your journal is labeled... | Look for this Paper Size: | Dimensions (Inches) |
Large / Portfolio | A4 or Letter | 8.3" x 11.7" or 8.5" x 11" |
Medium / Classic | A5 | 5.8" x 8.3" |
Pocket (Large) | A6 | 4.1" x 5.8" |
Pocket / Passport | A7 or B7 | ~2.9" x 4.1" |
Standard Traveler’s | TN Standard | 4.3" x 8.3" (Narrower than A5) |
**Wait—What about Traveler’s Notebooks?
If you are looking for fountain pen friendly paper for your Traveler's Notebook, be careful! The Standard TN size (4.3" x 8.3") is its own unique beast. It is the same height as an A5, but much narrower. It is one of the most unique "non-standard" sizes in the paper world. The Standard Traveler’s Notebook (TN) size is actually not part of the ISO (A-series) or the North American systems. It is a proprietary size popularized by the Japanese company Midori (now Traveler’s Company).
Compatibility Tip: Don't try to force an A5 refill into a Standard TN cover. Look specifically for "TN Standard" or "A5 Slim" inserts.
Calligraphy Tip: This narrow format is the perfect canvas for practicing vertical scripts or long-form journaling without the intimidation of a wide, empty page!
Understanding Paper Features
Understanding Weight: GSM vs. Basis Weight
If you’ve ever wondered why 100 lb Text paper feels thinner than 80 lb Cover paper, you aren’t alone. The American system is famously confusing because it depends on the "category" of the paper.
The Universal Metric: GSM
The rest of the world uses GSM (Grams per Square Meter). This measures the actual density of the paper. It is consistent across the board: a 1m x 1m sheet of 100 GSM paper weighs 100 grams. The higher the GSM, the thicker the paper. Simple.
The American Headache: Basis Weight (lbs)
In North America, we use Basis Weight. This is the weight of a 500-sheet ream of paper in its "uncut" (parent) size. The problem? The "uncut" size is different for every category of paper:
Bond Paper: Used for standard office printers. (Uncut size: 17" x 22")
Text Paper: A higher-quality, smoother paper used for brochures or book pages. (Uncut size: 25"x 38")
Cover Paper (Cardstock): Thick, stiff paper used for business cards and invitations. (Uncut size: 20" x 26")
The Result: Because a "Text" parent sheet is much larger than a "Bond" parent sheet, 70 lb Text is actually thinner than 28 lb Bond. It’s like comparing the weight of a dozen eggs to the weight of a dozen bricks—the "dozen" stays the same, but the items don't!
To keep your sanity, use GSM to compare across categories!
The "Translate to GSM" Cheat Sheet
Paper Type | Common US Name | Approx. GSM (Grams) | The "Hand-Feel" |
Bond | 20 lb Bond | 75 GSM (grams) | Standard, "cheap" copy paper. |
Bond / Text | 28 lb Bond / 70 lb Text | 105 GSM (grams) | High-quality, thick letterhead. |
Text | 100 lb Text | 150 GSM (grams) | High-end magazine page or brochure. |
Cover | 60 lb Cover | 160 GSM (grams) | Thin, flexible cardstock. |
Cover | 80 lb Cover | 215 GSM (grams) | Standard business card / Greeting card. |
Cover | 110 lb Cover | 300 GSM (grams) | Heavy-duty, stiff cardstock. |
Pro Tip: If you are buying paper online and aren't sure of the thickness, always look for the GSM, often just referred to as grams. It is the only way to compare a "Text" paper to a "Cover" paper accurately!
Why "Weight" Matters for Calligraphers
In the world of ink, not all 80 GSM paper is created equal. For fountain pens, you aren't just looking at weight; you are looking at surface sizing (the coating that keeps ink from soaking in).
What is Sizing, and why should you care?
Think of "sizing" as the invisible shield that protects your paper from your pen. In the papermaking process, manufacturers add starches or resins to control how the page reacts to moisture. Without this treatment, paper acts like a sponge, drinking up ink as fast as you can lay it down.
There are two levels to this: Internal Sizing is blended directly into the liquid paper pulp to give the sheet its core strength. However, for the calligrapher, Surface Sizing is the real hero. This is a final finish applied to the exterior of the page that creates a smooth "seal." This seal prevents the ink from diving into the fibers, keeping it crisp and vibrant on the surface instead.
How to Spot "Sizing" on the Label (Since they don't call it that!)
If you are looking at a pack of paper and it doesn't explicitly say "Fountain Pen Friendly," look for these keywords and industry terms that hint at high surface sizing:
"Vellum" or "Satin" Finish: These terms describe the smoothness of the surface. To achieve that glassy feel, the paper almost always has a heavy layer of surface sizing. Be careful with this one, however, you could inadvertently purchase something more similar to photo paper!
"Hard-Sized": If you see this, you’ve hit the jackpot. It’s a technical term meaning the paper has been specifically treated to resist liquid penetration.
"Hot Pressed" (specifically for watercolor/art paper): In the art world, "Hot Pressed" paper is pressed with heat to create a smooth, sealed surface. This is much better for calligraphy than "Cold Pressed," which is textured and absorbent.
"Ink-Resistant": This is often used on high-end drawing or marker paper. It's a direct signal that the surface sizing is strong enough to keep ink from feathering.
"Low Porosity": If a paper describes itself as "low porosity," it means the "pores" of the paper are sealed. This is a scientific way of saying the sizing is doing its job!
The Red Flags (When to stay away)
If you see these words, the paper likely has low or no surface sizing, making it a nightmare for fountain pens:
"Sketch" or "Rough": These are designed for dry media like graphite or charcoal. They are usually very absorbent and will make your fountain pen ink spread like a wildfire.
"Recycled Content": While eco-friendly, recycled fibers are often shorter and more "thirsty," leading to heavy feathering unless the brand specifically mentions a coating.
The current exceptions to this are Rhodia and Clairefontaine, which both have recyled fountain pen friendly paper!
Insider Secrets for Fountain Pen Friendly Paper
The following tips will help you troubleshoot problems that even "good" paper can't always solve.
The "Grain" of the Paper
Did you know paper has a grain, just like wood?
Why it matters: If you are folding your own journals or creating cards, folding against the grain will cause the paper (and your beautiful ink work) to crack or pucker.
The Calligraphy Hack: Sometimes a pen feels "scratchy" moving left-to-right but smooth moving up-and-down. This is often because you are fighting the grain of the paper.
"Coated" vs. "Uncoated" Paper
This is often confused with sizing.
Coated Paper: Although sizing acts like a coating it is not typically sold as a coated paper! This is like the shiny pages of a fashion magazine. While it stops bleed-through, fountain pen ink often never dries on it, or it "beads up" so much that the lines break apart.
Uncoated (Sized) Paper: This is what calligraphers want. It feels like paper, but the sizing acts as an invisible barrier. It gives the nib a little "tooth" to grip while keeping the ink crisp.
The "Atmosphere" Factor (Humidity)
This is a tip very few people talk about, but it’s a lifesaver for fountain pen users in humid regions.
The Tip: Paper is "hygroscopic"—it absorbs moisture from the air. If you leave your high-quality calligraphy paper out in a humid room, it will actually lose its sizing performance over time.
The Advice: Store your premium paper in a drawer or a sealed container to keep it "crisp." If your favorite paper suddenly starts feathering, it might just be damp!
Finding Your "Sweet Spot": What to Look For
If you are shopping for fountain pen friendly paper, don't just grab the heaviest cardstock on the shelf. Instead, look for this specific combination of weight and surface treatment based on how you write:
For the Everyday Writer
Look for: 80–90 GSM (grams) with High Surface Sizing.
Why: This is the gold standard for notebooks. It’s thick enough to prevent bleed-through but thin enough that a 200-page journal isn't too bulky. High surface sizing ensures that standard fine or medium nibs won't feather.
Top Pick: Rhodia or Clairefontaine 90g pads.
For the "Sheen Queen" & Shading Enthusiast
Look for: 52–68 GSM (grams) with Extreme Surface Sizing.
Why: It sounds counter-intuitive to go thinner, but legendary papers like Tomoe River are designed this way. The extreme surface sizing keeps the ink "beaded" on top for a long time. This is the only way to see the multi-tonal shading and metallic sheen of specialty inks.
Top Pick: Tomoe River 52 GSM or Sanzen paper.
For the Bold Calligrapher & Flex Nib User
Look for: 100–120 GSM (grams) with Moderate to High Surface Sizing.
Why: Flex nibs and broad calligraphy pens dump a massive amount of ink onto the page. You need the extra physical "body" of a higher GSM paper to absorb that volume without the page warping or "ghosting" too heavily, but you still need that surface sizing to keep your hairlines crisp.
Top Pick: Premium 120 GSM Letterhead or Calligraphy Practice Pads.
Looking for another kind of paper?
Have questions about the paper that is right for you?
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