Static vs Expanding Vaginal Dilators: How They Differ and How to Choose

Key Takeaways 

• Static dilators come in fixed sizes. Expanding dilators allow gradual, millimeter-by-millimeter adjustment within a single device.
• The most important factor in how quickly dilation therapy works is consistency — and the tool you can stay with regularly is the one most likely to help you progress (Wallace et al., 2019).
• Data shows static dilator discontinuation rates of up to 57% by 6 months (Liu et al., 2021). Reducing the stress that causes women to stop is a meaningful design consideration.
• Start with the smallest size or narrowest setting you can tolerate without forcing. A comfortable starting point is almost always more effective than an ambitious one (Cleveland Clinic, 2024).
• When in doubt, consult your healthcare provider or pelvic floor physical therapist about which type and starting size makes sense for your situation.

When you are managing vaginismus or painful sex, a vaginal dilator is one of the treatment options available to you. Choosing the right one is almost as important as finding a provider who understands your situation. One of the key decisions you will face is between a static dilator set and a dynamic expanding dilator. There are real, factual differences between the two — and understanding them can help you make a choice that supports the thing that matters most: staying consistent with your therapy (Wallace et al., 2019).

Expanding vs Static Vaginal Dilators: Which Is Better?

Static vaginal dilators can be useful when you want clear size steps and a traditional set-based approach. Expanding dilators can be helpful when you want more gradual size progression, fewer jumps between sizes, and one device that adjusts slowly over time.

For many people with vaginismus or penetration pain, the better choice is the one that feels less intimidating, easier to use consistently, and more comfortable for gradual progress (Macey et al., 2015). The key is not just whether a dilator is static or expanding — it is whether it allows you to start at a tolerable point and progress at a pace your body can handle.

How Static Dilators Work

Static vaginal dilators come in a set of graduated sizes, with each dilator being slightly larger than the one before it (Cleveland Clinic, 2024). The smallest is usually smaller than a tampon; the larger sizes are typically representative of progressively greater levels of penetration.

When using a set of static dilators, you start with the smallest size you can tolerate, and work your way up over time as your comfort increases. The controlled size progression helps your body adjust gradually. Static dilators are available in single sizes or as sets — and when purchasing a set, you may not need every size included.

How Expanding Dilators Work 

An expanding or dynamic dilator is a single device that adjusts in size — eliminating the need to remove and reinsert progressively larger dilators. Rather than distinct size steps, an expanding dilator allows continuous adjustment, often in smaller increments than available with static sets.

Milli is an FDA-cleared expanding vaginal dilator that expands from 15mm to 40mm in 1mm increments, controlled by the user with a button. It does not require removal and reinsertion to change size and includes optional integrated vibration to support muscle relaxation during sessions (Materna Medical, n.d.).

How They Differ: A Factual Comparison

The following table reflects factual differences between static dilator sets and Milli as an expanding dilator. It is intended as educational context, not a recommendation or endorsement of one approach over another. The right choice depends on your individual situation and the guidance of your healthcare provider.

Feature	Static Dilator Sets	Milli (Expanding Dilator)
Sizing approach	Fixed sizes — separate device for each size step	Fully adjustable 15mm–40mm in 1mm increments within one device
Reinsertion required to change size	Yes — must remove and reinsert a larger size	No — expands within the vagina without removal
Number of devices	Multiple (typically 4–7 sizes per set)	One all-in-one device
Vibration option	Not typically available	Optional integrated vibration (low and high settings)
FDA clearance	Varies by manufacturer — not all are FDA-cleared	FDA-cleared; only OTC expanding dilator with FDA clearance
Storage	Multiple items to store and clean	Single device with discreet charging case

Note: Not all dilators on the market have been FDA-cleared. We recommend confirming FDA clearance before purchasing any dilator for medical use. 

How to Choose the Right Starting Size

The right starting point is usually the smallest size or narrowest setting you can tolerate without forcing (Cleveland Clinic, 2024). For some people, that may be smaller than a tampon. For others it may mean starting at the narrowest possible setting and expanding very slowly from there.

When choosing a starting point, consider three things: your current comfort with penetration, whether tampon insertion or pelvic exams are painful, and how much fear or muscle guarding shows up before or during insertion (Macey et al., 2015). If penetration is very painful or currently not possible, starting smaller and progressing more gradually is almost always the better approach.

You do not need to start with a size that feels challenging. A better starting point is one that allows your body to stay as relaxed as possible — because relaxation is what allows progress to build (Wallace et al., 2019). For techniques that help with pelvic floor relaxation before and during sessions, see our article How to Relax Your Pelvic Floor.

Why Consistency Is the Most Important Factor

Whichever type of dilator you choose, consistency is a critical factor in how quickly progress happens (Wallace et al., 2019). Short, regular sessions over time produce better results than infrequent attempts at larger sizes. This is true for both static and expanding dilators.

This is also where design differences can matter in practice. Data on static dilator use shows discontinuation rates of 41% by 3 months and up to 57% by 6 months (Liu et al., 2021). When therapy feels physically or emotionally stressful — whether because of size jumps, reinsertion discomfort, or the process feeling overwhelming — women are more likely to stop before reaching their goals (Macey et al., 2015).

A tool that reduces that stress makes it easier to stay with therapy. In a recent clinical study of Milli users — who used an expanding dilator with gradual 1mm progression and optional integrated vibration — more than 85% stayed on track with recommended use at 6 months, and 85% made measurable progress toward intercourse within 90 days (Materna Medical, n.d.).

The data does not mean expanding dilators are right for everyone. It means that the tool you can use consistently, in sessions you can tolerate and return to, is the one most likely to get you where you want to go (Wallace et al., 2019). For more on what the research shows about dilation therapy overall, see our article Do Vaginal Dilators Work?.

“Data on static dilators shows discontinuation rates of up to 57% by 6 months. The tool that is easiest to use consistently is the one most likely to get you where you want to go.”

What About Material and Storage?

Static dilators come in a variety of materials, including hard plastic, glass, and silicone (Liu et al., 2021). Some people prefer a firmer feel; others find silicone more comfortable or less intimidating. Material can affect how a dilator feels during a session, so it is worth considering not just size but also texture and flexibility when choosing the option you are most likely to use consistently.

Storage is a practical consideration too. With a static set, you will have multiple sizes to store and clean between sessions. Milli is a single device with a discreet charging case. For some women, having fewer items to manage removes a small but real barrier to getting started (Lee, 2018). Whatever you choose, follow the care and cleaning instructions for any dilator you use.

The Bottom Line

Your journey is yours. The best dilator is the one that helps you begin at a manageable starting point and stay consistent enough to progress — without forcing (Wallace et al., 2019). Static and expanding dilators can both be useful, and the right fit depends on your individual situation, your comfort level, and what your healthcare provider recommends.

If you are unsure where to begin, ask your healthcare provider or pelvic floor physical therapist for guidance.

FAQs

Expanding vs static vaginal dilators: which is better?

Neither is universally better. Static dilators offer fixed size steps and a traditional set-based approach. Expanding dilators allow more gradual progression within a single device (Liu et al., 2021). The better option depends on what feels more manageable, comfortable, and sustainable for your specific situation and starting point.

How do I choose the right dilator size and starting point?

Start with the smallest size or narrowest setting you can tolerate without forcing (Cleveland Clinic, 2024). The best starting point is one that allows your body to stay as relaxed as possible. If penetration is very painful or not currently possible, starting smaller and progressing more slowly is usually the better approach.

Should I start with the smallest dilator even if it feels too easy?

Usually yes. Starting too small is almost always better than starting too large, especially if your body is tense or penetration feels intimidating. Progress builds from comfort and consistency, not from pushing ahead too quickly.

Are expanding dilators better for vaginismus?

They may be especially helpful for people who find the size jumps between static dilators too intimidating, or who want more control over the pace of progression (Liu et al., 2021). But some people do well with static sets, particularly when they like clear size milestones. For a full overview of vaginismus and its treatment options, see our Vaginismus Overview article.

Why do some women stop using static dilators?

Data shows that static dilator discontinuation rates can be as high as 57% by 6 months (Liu et al., 2021). Common reasons include discomfort from size jumps, the friction of removing and reinserting larger sizes, and the process feeling clinically stressful (Macey et al., 2015). When therapy feels manageable and sessions feel tolerable, women are more likely to stay consistent — and consistency is a critical factor in how quickly progress happens (Wallace et al., 2019).

Do I need an FDA-cleared dilator?

Not all dilators on the market have been FDA-cleared. We recommend confirming FDA clearance before purchasing any dilator for medical use, since clearance indicates the device has been evaluated for safety and effectiveness for its indicated use (Cleveland Clinic, 2024).

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Sources

• Cleveland Clinic. (2024). Vaginal dilators. https://my.clevelandclinic.org/health/treatments/24971-vaginal-dilators
• Lee, Y. (2018). Patients’ perception and adherence to vaginal dilator therapy: A systematic review and synthesis employing symbolic interactionism. Patient Preference and Adherence, 12, 551–560. https://doi.org/10.2147/PPA.S158168
• Liu, M., Juravic, M., Mazza, G., & Krychman, M. L. (2021). Vaginal dilators: Issues and answers. Sexual Medicine Reviews, 9(2), 212–220. https://doi.org/10.1016/j.sxmr.2019.11.005
• Macey, K., Gregory, A., Nunns, D., & das Nair, R. (2015). Women’s experiences of using vaginal trainers (dilators) to treat vaginal penetration difficulties diagnosed as vaginismus: A qualitative interview study. BMC Women’s Health, 15(1), 49. https://doi.org/10.1186/s12905-015-0201-6
• Materna Medical. (n.d.). POMPOM clinical study results (Data on file, KEY0054 and supporting references KEY0050–KEY0053).
• Wallace, S. L., Miller, L. D., & Mishra, K. (2019). Pelvic floor physical therapy in the treatment of pelvic floor dysfunction in women. Current Opinion in Obstetrics and Gynecology, 31(6), 485–493.