Hario Slim Plus: The Skinny Manual Grinder That Travels Well

The Hario Slim Plus (also called the Mini Slim Plus or MSS-1DTB) is one of the slimmest manual coffee grinders you can buy. If you've been looking for a hand grinder that fits in a bag, a coat pocket, or alongside your AeroPress kit, the Slim Plus is built for exactly that. Priced around $30-45, it's an affordable entry into manual grinding, though it comes with tradeoffs you should know about.

I've carried a Hario Slim Plus on weekend trips and used it in hotel rooms where my only option for coffee was a sad sachet of instant. It changed those mornings for the better. But I've also been frustrated by its limitations, particularly with adjustment precision and grind consistency. Let me give you the full picture.

Design and Form Factor

The Slim Plus is about 6 inches tall and under 3 inches wide. It weighs roughly 250 grams, which is lighter than a can of soda. The body is transparent BPA-free plastic with a stainless steel burr assembly and a slim metal crank handle that detaches for storage.

The transparent body is actually useful. You can see the beans dropping into the burrs as you grind and monitor the grounds collecting in the lower chamber. The lower chamber detaches and holds about 24 grams of ground coffee.

What Sets It Apart

The defining feature is the shape. While most hand grinders are cylindrical with a wide body, the Slim Plus tapers to a narrow profile. It sits comfortably inside a standard AeroPress plunger, which means you can nest them together for travel. Hario designed this intentionally, and it's a clever move.

The handle attaches via a hex nut on top and pops off in seconds. With the handle removed, the grinder is essentially a tube that fits almost anywhere.

The Ceramic Burrs

The Hario Slim Plus uses ceramic conical burrs. This is standard for Hario's consumer grinder line and has both advantages and disadvantages.

Advantages of Ceramic

  • Longevity: Ceramic stays sharp longer than steel, often lasting several years before showing wear
  • No heat transfer: Ceramic doesn't conduct heat like steel, so your grounds don't warm up during grinding
  • Affordability: Ceramic burrs keep the price low

Disadvantages

  • Inconsistency: The ceramic burrs in the Slim Plus produce a wider range of particle sizes compared to steel burrs at the same price point. You'll get more fines mixed with your desired grind size.
  • Slower cutting: Ceramic requires more revolutions to grind the same amount of coffee. My 18-gram dose takes about 60-70 seconds at a medium setting, compared to 35-40 seconds on a steel-burr grinder like the Timemore C2.
  • Brittleness: Drop the grinder on a hard surface and the burrs can crack. I haven't broken mine, but I know people who have.

Grind Settings and Consistency

The adjustment mechanism on the Slim Plus is a friction-based system with a nut at the bottom of the burr shaft. Turn it clockwise for finer, counterclockwise for coarser. There are subtle click stops, but they're not very distinct. This makes finding and repeating a specific setting more difficult than on grinders with clear indexed clicks.

Performance by Brew Method

AeroPress (medium-fine): This is where the Slim Plus works best. The AeroPress is forgiving of grind inconsistency, and the medium-fine range is where the ceramic burrs produce the most even output. I've made genuinely enjoyable AeroPress coffee with this grinder.

Pour-over (medium): Acceptable but not great. You'll notice some uneven extraction in your V60 or Kalita Wave cups. The fines extract faster than the larger particles, giving you a slight muddy quality that a more consistent grinder avoids. For casual pour-over, it's fine. For dialing in specialty beans, you'll want something better.

French press (coarse): The coarse settings are the weakest point. The adjustment mechanism has a lot of play at the coarse end, making it hard to get a consistent setting. The grind looks uneven to the naked eye, with visible differences between the largest and smallest particles. Your French press coffee will have more sediment than usual.

Espresso: No. The Slim Plus cannot grind fine enough or consistently enough for espresso. Don't try.

Hario Slim Plus vs. Hario Skerton Pro

Hario makes several manual grinders, and the comparison between the Slim Plus and the Skerton Pro comes up often.

The Skerton Pro is larger, heavier, and has a stabilizing plate on the lower burr that improves grind consistency. It costs about $10-15 more. For home use where portability doesn't matter, the Skerton Pro is the better grinder.

The Slim Plus wins on portability alone. If you're choosing between them specifically for travel, the Slim Plus is the obvious pick. For everything else, the Skerton Pro performs better.

Who This Grinder Serves Best

After using the Slim Plus in various situations, here's my take on who should buy it and who should skip it.

Buy It If

  • You need the most compact manual grinder possible for travel
  • You're an AeroPress user who wants fresh grounds on the road
  • You want to spend under $40 on a manual grinder and portability is the priority
  • You're testing whether manual grinding appeals to you before investing in a better unit

Skip It If

  • You want the best grind quality for under $80 (the Timemore C2 beats it at a slightly higher price)
  • You brew primarily pour-over or French press at home
  • You're looking for a daily driver grinder
  • Espresso is in your plans

For a broader look at what's available, the best coffee grinder guide covers manual and electric options across all budgets.

Tips for Getting the Best Results

Over many sessions with the Slim Plus, I've picked up a few tricks that improve the output:

  1. Grind only what you need: Fresh is the whole point. Don't grind 40 grams and save half for tomorrow.

  2. Shake between pulses: Every 15-20 revolutions, stop cranking and shake the grinder vertically. This redistributes beans and prevents large fragments from hiding above the burrs.

  3. Mark your setting: Once you find a grind size that works for your brew method, use a permanent marker to make a small dot on the adjustment nut aligned with a reference point on the body. This makes it easy to return to the same setting.

  4. Don't force dark roasts: Very oily, dark-roasted beans can clog the ceramic burrs. If you notice the handle becoming much harder to turn, stop and clean the burrs before continuing.

  5. Use consistent pressure on the handle: A smooth, steady rotation produces better results than jerky, fast cranking. Aim for about one revolution per second.

Maintenance

The Slim Plus is easy to maintain:

  • Brush the burrs after every few uses with a stiff-bristled brush
  • Remove the adjustment nut and pull out the burr shaft monthly for a deeper clean
  • Tap out retained grounds by turning the grinder upside down and gently knocking it against your palm
  • Don't use water on the ceramic burrs (they're porous and can absorb moisture)
  • Check the adjustment nut periodically to make sure it hasn't shifted from your preferred setting

Replacement burrs are available from Hario and cost about $8-12. Easy to swap out if your originals crack or wear down.

FAQ

Does the Hario Slim Plus fit inside an AeroPress?

Yes. The Slim Plus was designed to nest inside the AeroPress plunger for travel. With the handle detached, it slides right in. This makes the AeroPress + Slim Plus combo one of the most compact travel brewing setups available.

How fine can the Hario Slim Plus grind?

The finest setting produces a medium-fine grind suitable for AeroPress or Moka pot. It cannot reach true espresso fineness, and attempting very fine settings often results in inconsistent, dusty output with the ceramic burrs.

Is the Hario Slim Plus better than the Timemore C2?

No. The Timemore C2 has superior steel burrs, better grind consistency, and a more precise click adjustment system. The only area where the Slim Plus wins is compactness and weight. If portability is your top priority, the Slim Plus has an edge. For everything else, the C2 is the better buy. Check the top coffee grinder guide for detailed comparisons.

How long does grinding take with the Hario Slim Plus?

About 60-70 seconds for an 18-gram dose at a medium grind setting. Finer settings take longer (up to 90 seconds), and coarser settings are slightly faster (45-50 seconds). It's not the fastest manual grinder, but the short sessions are manageable for single cups.

My Honest Recommendation

The Hario Slim Plus does one thing very well: it fits in places other grinders don't. If that's your primary need, buy it without hesitation. But if you're looking for the best grind quality at this price, spend the extra $20 on a Timemore C2. The Slim Plus is a convenience tool, and a good one, but grind quality takes a back seat to portability in its design priorities.