There may come a day when you need a new bowl or slide—perhaps because you broke the old one, or you just want an upgrade. Shopping for a replacement can feel daunting if you aren’t already familiar with joint sizes, genders, and other nuances. In this guide, we’ll walk you through all the basics to help you find the perfect fit with confidence.
1. Understanding Joint Sizes
What’s the difference between 14.5 mm vs. 14 mm, or 18.8 mm vs. 18 mm and 19 mm?
Technically, 14.5 mm and 18.8 mm are the precise measurements of these common joint sizes. However, many people (and smoke shops) round them for simplicity’s sake. That’s why you’ll often see them listed simply as 14 mm, or 18 mm/19 mm. Despite the numbers, they are effectively the same size. Here are the standard sizes you’ll come across:
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10 mm (Sometimes referred to as “Micro,” “Nano,” or occasionally “12 mm”)
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14 mm (Often labeled 14.4 mm or 14.5 mm, the most common size)
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19 mm (Sometimes labeled 18.8 mm or referred to as 18 mm)
Since these three standard sizes may have slightly different labels, don’t be alarmed by the variations.
Quick Trick to Measure at Home with a Dime
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14 mm joint: A dime will sit about the same diameter as the opening.
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19 mm joint: A dime will fall into the joint because the joint is larger than the coin.
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10 mm joint: The opening will be significantly smaller than a dime.
2. Male vs. Female Joints
Glass joints on bongs, bowls, dab rigs, and other attachments come in two genders:
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Male: A narrower, protruding joint that fits into a female joint.
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Female: A wider joint that goes over a male joint.
Which one do you have?
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If your bong’s joint protrudes outward, it’s male and will need a female bowl/slide.
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If your bong’s joint forms an opening, it’s female and will require a male bowl/slide.
As a simple rule of thumb: Male goes into female; female goes on top of male.
Another way to tell them apart is that the male joint's ground section is on the outside. The female joint's ground section is inside.
3. Matching the Bowl to the Downstem
Why Size Matters
A bowl attaches to the downstem (or joint) on the bong. If these components aren’t the same size (e.g., a 14 mm bowl for a 14 mm downstem), you won’t get an airtight seal. This reduces airflow and will waste product because you won’t be able to pull in a full hit.
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10 mm bowls/slides pair with 10 mm downstems.
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14 mm bowls/slides pair with 14 mm downstems.
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19 mm bowls/slides pair with 19 mm downstems.
Having the right fit guarantees the proper airflow, which is crucial for smoother, more potent hits.
4. The Most Common Bowl Size: 14 mm
If you’re feeling overwhelmed while shopping, know that 14 mm (often listed as 14.5 mm or 14.4 mm) is the most standard size, especially for small- to medium-sized bongs and dab rigs. You’ll find the greatest variety of bowls, bangers, and other glass accessories in 14 mm. If you’re unsure, there’s a good chance 14 mm is what you need.
However, if you have a very large bong, you might require 19 mm. And if you have an ultra-compact or pendant rig, you might need 10 mm attachments.
5. Putting It All Together
Here’s a quick checklist to use when you’re ready to buy a new bowl, banger, ash catcher, or any other glass accessory:
Identify Your Joint’s Gender
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Male joint? You’ll need a female accessory.
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Female joint? You’ll need a male accessory.
Determine Your Joint Size
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10 mm, 14 mm, or 19 mm
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Use the dime trick if you’re unsure.
Make Sure Everything Lines Up
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Matching size and gender ensures an airtight seal and smooth airflow.
6. Final Thoughts
Don’t let the numbers and terms confuse you: once you understand the basics of joint size and gender, finding the right bowl or slide is easy. As long as you match the size (10 mm, 14 mm, or 19 mm) and the proper gender (male or female), you’ll be on your way to smoother, more satisfying sessions.
Whether you’re replacing a broken bong bowl or customizing a setup, having this knowledge will save you time, money, and frustration—so you can get back to enjoying your favorite herbs or concentrates without missing a beat.
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