Drawing a capital I bubble letter is harder than it looks. You’d think the straightest letter in the alphabet would be the easiest to puff up, but that’s exactly where most people trip up. It ends up looking like a soggy fry. Or a bone. Sometimes even a very sad rectangular pillow.
If you've ever tried to doodle a name on a birthday card or a poster, you know the struggle of making that vertical bar look intentional rather than just... thick.
Typography, even the fun, "street art" variety we call bubble letters, relies on a weird mix of geometry and optical illusion. When we transition a standard serif or sans-serif "I" into a rounded, inflated shape, we’re fighting against the human eye's tendency to see straight lines as rigid. To make a bubble letter work, you have to embrace the curve. It’s about volume, not just outlines.
👉 See also: Why Prawn Malai Curry is Still the King of Bengali Comfort Food
The Anatomy of a Good Capital I Bubble Letter
Most people start with a stick. They draw a line and try to wrap a "cloud" around it. Stop doing that.
Instead, think about the capital I bubble letter as a physical object filled with air. If you pumped air into a metal "I," the corners wouldn't stay sharp. They’d push outward. The middle might even pinch slightly, or the top and bottom bars (the serifs) would bulge like little sausages.
There are basically two ways to handle this. You have the "Slab" style and the "Classic Pillar" style.
The Slab style keeps the crossbars at the top and bottom. It looks more formal, if a bubble can be formal. You’re essentially drawing three rounded rectangles that have fused together. The Pillar style is just the vertical bar, rounded off at the ends. It's simpler, but it’s harder to make it look like an "I" and not a lowercase "l" or the number one. Context matters a lot here. If you’re writing "ICE," a pillar works. If you’re writing "INDIGO," you might want the crossbars to ensure readability.
Dealing with the "Bone" Effect
One of the biggest complaints I hear from students and hobbyists is that their letter looks like something a dog would chew on. This happens when the middle of the vertical bar is too skinny and the top/bottom are too wide.
To avoid the bone look, keep your "waistline" consistent. Take a look at the work of legendary graffiti artists like Phase 2, who basically pioneered the "softie" bubble style in the 1970s. Their letters had weight. They didn't just taper off into nothing. The thickness of the vertical stroke should stay relatively uniform until it meets the rounded corners.
Gravity and Overlap: Making it Pop
Bubble letters aren't flat. Or they shouldn't be.
To get that 3D look that makes a capital I bubble letter jump off the page, you need to understand where your light is coming from. Most artists default to a top-left light source. This means your shadows—the "3D block" part of the letter—will fall to the bottom and the right.
But here is a pro tip: overlap.
If the "I" is next to an "M" or a "B," let them touch. Let them squish. In the world of bubble graffiti, letters aren't socially distanced. They are a crowd. If the "I" is tucked slightly behind the letter preceding it, you create instant depth without needing to be a master of perspective.
You should also play with the "shine." A tiny white oval or a couple of dots in the upper corner of each "bump" makes the letter look wet or plastic. It's a simple trick, but it’s the difference between a flat drawing and something that looks like a balloon.
Common Mistakes Beginners Make
It’s easy to get frustrated. You’re drawing, you erase, you draw again, and it still looks "cheap." Usually, it's one of these three things:
- Weak Outlines: You’re being too timid. A bubble letter needs a bold, confident border. If your hand is shaking, it shows. Use your whole arm to draw the curves, not just your fingers.
- Inconsistent Volume: One crossbar is huge and the other is tiny. It makes the letter look like it’s tipping over. Unless you're going for a "funhouse mirror" vibe, try to keep the top and bottom symmetrical.
- Negative Space Fear: Sometimes people leave too much room inside the letter, or they don't leave enough. A capital I bubble letter needs to feel full. If the "skin" of the bubble looks like it's sagging, add more curve.
Tools of the Trade
Honestly, you can do this with a Bic pen and a napkin. But if you want that crisp, Discover-worthy look, markers matter.
For the outline, use something with a consistent flow. Posca pens (acrylic paint markers) are the gold standard for a reason. They lay down opaque color that hides the pencil marks underneath. If you're working on paper, Copic markers or any alcohol-based brand will give you those smooth gradients that make the letter look like it has a curved surface.
If you are working digitally, like in Procreate or Illustrator, use a "stabilization" setting on your brush. It smooths out the wobbles in your stroke, giving you those perfect, buttery curves that define the bubble aesthetic.
Beyond the Basics: Style Variations
Once you’ve mastered the standard shape, you can start getting weird with it.
You could try the "Drip" style, where the bottom of the capital I bubble letter looks like it’s melting. You just extend the bottom curves into long, teardrop shapes.
Or there’s the "Beveled" look. Instead of a smooth curve, you use short, straight segments to create a faceted, diamond-like appearance. It’s still technically a bubble letter because of the overall proportions, but it feels more "tech" and less "street."
Then there's the "Negative Space" trick. Draw the "I" by drawing everything around it. This is a bit more advanced, but it’s great for logo design. You’re essentially carving the letter out of a solid block of color using rounded edges.
How to Practice Without Getting Bored
Don't just draw the letter "I" over and over. That’s a one-way trip to Burnout City.
Write words that are "I" heavy. "ILLUSION." "MINIMAL." "PACIFIC."
Focus on how the capital I bubble letter interacts with its neighbors. Does the top bar of the I sit over the L? Or does the L lean into the I? This is where the real artistry happens.
If you're struggling with symmetry, fold a piece of paper in half. Draw half the "I" on the crease, then trace it to the other side. It feels like cheating, but it’s actually a great way to train your brain to see the correct proportions. Eventually, you won't need the fold.
Actionable Next Steps
- The Ghosting Technique: Before you put ink to paper, "draw" the letter in the air or very lightly with a hard pencil (like a 2H). This builds the muscle memory for the curve before you commit.
- Corner Rounding: Start by drawing a very boxy, rigid capital "I." Then, go back and round off every single sharp corner. Slowly increase the radius of those rounds until the straight lines start to bow outward. This is the easiest way to learn how volume works.
- The Highlight Rule: Always put your highlights on the "fattest" part of the bubble. If the middle of your "I" is the thickest, the shine goes there. If the top bar is the thickest, put it there.
- Invert Your Colors: Try drawing a black bubble with a white outline. It forces you to look at the shape differently and often reveals where your curves are lopsided.
The capital I bubble letter is a deceptively simple foundation for much more complex typography. Once you get the "puff" right on this one, letters like "S" and "R"—which are notoriously difficult—start to make a lot more sense. It's all about managing the air inside the shape. Keep it consistent, keep it bold, and don't be afraid to let your letters get a little bit crowded.