If you love ultra-fine writing, you’ve probably narrowed your choices down to two pens: the Uni-ball Signo DX and the Pilot Juice Up. Both are Japanese-made, both deliver incredibly precise lines, and both have earned cult followings among planner enthusiasts and journalers. Both also feature in our best Japanese gel pens ranking. But they approach fine writing from different engineering philosophies.
We’ve tested both pens side by side for months — writing on Hobonichi Tomoe River paper, Kokuyo Campus, cheap copier stock, and everything in between. Here’s our honest take on how they compare.
Quick Answer: The Pilot Juice Up is the better pen overall. Its Synergy tip technology delivers a smoother, more consistent writing experience than the Signo DX, and its ink colors are noticeably more vivid. The Uni-ball Signo DX wins on waterproof permanence and is the better choice for archival use and documents that may get wet. Choose the Juice Up for journaling and planners; choose the Signo DX for permanence and everyday reliability.
At a Glance
| Feature | Uni-ball Signo DX 0.38mm | Pilot Juice Up 0.4mm |
|---|---|---|
| Price | ~$2.50 per pen | ~$3 per pen |
| Tip Size | 0.38mm (also 0.28, 0.5mm) | 0.4mm (also 0.3, 0.5mm) |
| Ink Type | Pigment gel (waterproof) | Gel (Synergy tip) |
| Dry Time | ~3-4 seconds | ~2-3 seconds |
| Waterproof | Yes (pigment ink) | No (dye-based) |
| Colors | 8 colors | 24 colors |
| Body Style | Classic capped, slim | Retractable, textured grip |
| Weight | ~9g | ~11g |
| Best For | Archival writing, documents | Planners, journaling, color coding |
| Rating | 4.4/5 | 4.6/5 |
| Uni-ball Signo DX 0.38mm | Winner Pilot Juice Up 0.4mm | |
|---|---|---|
| Price | ~$2.50 | ~$3 |
| Rating | ||
| Best For | Archival writing, tiny handwriting, documents that may get wet | Planner enthusiasts, journalers, color-coding systems |
| Tip Technology | Stainless steel cone | Synergy (spring-loaded cone) |
| Ink Permanence | Waterproof, fade-resistant | Dye-based, not waterproof |
| Grip | Rubber grip section | Textured rubber grip |
| Mechanism | Capped | Retractable (click) |
| Smoothness | 3/5 | 5/5 |
| Ink Quality | 4/5 | 5/5 |
| Line Precision | 5/5 | 4/5 |
| Color Range | 2/5 | 5/5 |
| Durability | 5/5 | 3/5 |
| Value | 4/5 | 4/5 |
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| Check Price on Amazon | Check Price on Amazon |
*Prices shown are approximate at time of writing. Check retailer for current pricing.
Writing Experience
Uni-ball Signo DX
The Signo DX has a traditional capped design and a stainless steel cone tip. On smooth paper like Tomoe River, it writes cleanly with excellent line precision. On rougher paper, you’ll feel a slight feedback — not unpleasant, but noticeable compared to the Juice Up. The pigment ink lays down a consistent line, though we’ve occasionally experienced skipping when the pen sits unused for a few days.
Pilot Juice Up
The Juice Up’s Synergy tip technology is what sets it apart. The spring-loaded cone tip applies consistent pressure regardless of your writing angle, resulting in effortlessly smooth writing from the very first stroke. There’s virtually no break-in period, no skipping, and no variation in line quality. It’s one of the smoothest ultra-fine pens we’ve ever tested.
Winner: Pilot Juice Up. The Synergy tip technology delivers a noticeably smoother, more consistent experience.
Ink Quality & Color Range
The Signo DX uses pigment-based ink that’s truly waterproof once dry. This makes it the clear winner for archival applications — if you need your writing to survive coffee spills, rain, or decades of storage, the Signo DX is your pen. However, the color range is limited to 8 standard colors.
The Juice Up uses dye-based gel ink that’s more vivid and saturated than the Signo’s pigment ink. Colors pop off the page, especially the pastel and metallic options. With 24 colors available (in Japan; about 12 are easy to find internationally), the Juice Up is the better choice for color-coding and decorative writing.
Winner: Depends on your priority. Signo DX for permanence, Juice Up for vibrancy and variety.
Paper Compatibility
We tested both pens on five common paper types:
| Paper | Signo DX | Juice Up |
|---|---|---|
| Tomoe River (52 gsm) | Excellent — no bleed, minimal ghosting | Excellent — no bleed, slightly more ghosting |
| Kokuyo Campus | Excellent — crisp lines | Excellent — smooth and vivid |
| Midori MD | Very good — slight feedback | Excellent — buttery smooth |
| Cheap copier paper | Good — some feathering at 0.38mm | Good — minimal feathering at 0.4mm |
| Leuchtturm 1917 | Very good | Very good |
Both pens handle quality Japanese paper beautifully. The Juice Up has a slight edge on premium paper, while the Signo DX’s pigment ink resists feathering better on cheap paper.
Value & Availability
The Signo DX at ~$2.50 is one of the best values in ultra-fine pens. It’s available worldwide through Amazon, stationery shops, and even some office supply stores. Refills are not available — it’s a disposable pen.
The Juice Up at ~$3 costs slightly more but offers a premium experience that justifies the price. It’s also disposable, though its retractable mechanism feels more durable. Availability outside Japan is more limited, but Amazon carries most colors.
Winner: Signo DX on pure value. The Juice Up justifies its price with a better experience, but the Signo DX delivers exceptional quality per dollar.
Our Verdict
The Pilot Juice Up wins this comparison for most people. Its Synergy tip technology delivers a smoother, more enjoyable writing experience, and the extensive color range makes it the better choice for planners and journals. It’s the pen that makes you want to write more.
The Uni-ball Signo DX remains the superior choice for archival use. If waterproof ink matters to you — for important documents, field notes, or anything that might get wet — the Signo DX is the clear pick. It’s also the better budget option. For another perspective on gel pen matchups, see our best Japanese gel pens roundup.
Our recommendation: Buy the Juice Up for your daily journaling and planning. Keep a few Signo DX pens for important documents and permanent annotations. They complement each other perfectly.
Frequently Asked Questions
Which pen is better for left-handed writers?
The Pilot Juice Up has a faster dry time (~2-3 seconds vs ~3-4 seconds), making it slightly better for left-handed writers. However, neither pen is as fast-drying as the Pentel EnerGel, which remains our top pick specifically for lefties. You can read more about it in our Pentel EnerGel vs Pilot G2 comparison.
Can I use these pens on Hobonichi planners?
Both pens work beautifully on Hobonichi’s Tomoe River paper. The Juice Up provides a slightly smoother experience, while the Signo DX offers better permanence. Many Hobonichi users keep both.
Are refills available for either pen?
Neither pen offers separate refill cartridges — both are designed as disposable pens. If refillability is important to you, consider the Pilot Juice (not Juice Up) or the Pentel EnerGel, both of which accept refills.
Which pen has better resale value for collectors?
Limited-edition Pilot Juice Up sets (especially seasonal Japanese exclusives) tend to hold their value well among stationery collectors. The Signo DX doesn’t have as active a collector market.