What Size Vacuum Bell Do I Need? A Sizing Guide

The size of a vacuum bell is set by the diameter that covers your indentation and seals on the flat skin around it, not by your age or height. The reviewed devices come in three diameters, 16, 19 and 22 cm, plus a model shaped for the female chest. Matching the depth and width of your hollow to the bell is the whole task.

Key points

  • Loufopoulos and colleagues (2021) reviewed the therapy and reported the device is supplied in three diameters, 16, 19 and 22 cm, plus a model shaped for the female chest.
  • Haecker (2016), reporting a cohort of about 450 patients aged 2 to 61, described the same small set: three device sizes plus a version fitted for adolescent and adult female patients.
  • Size is chosen so the bell spans the whole depression and its centre sits over the deepest point, while its rim seals on the flatter skin around the hollow.
  • Age and height do not set the size. The same diameters served patients across a wide age range (Haecker 2016), because the bell must match the area and depth of the indentation, not the body.
  • No validated guidelines exist for the therapy, sizing included (Haecker et al. 2024), so a size is matched to the individual chest rather than read off a formula.

The short answer, expanded

A vacuum bell is a silicone suction cup with a hand pump. It works by sealing against the skin around a sunken part of the chest and applying negative pressure that lifts the sternum and the rib cartilage attached to it. For that seal to form and hold, the rim of the bell has to rest on firm, relatively flat skin all the way around the indentation, while the cup itself spans the hollow and reaches over its deepest point. That single requirement is what sizing is about.

It follows that the number you need is not read off your age, your height or your weight. It is set by the geometry of your own indentation: how wide the sunken area is, where its deepest point sits, and how much flat skin surrounds it. The reviewed devices come in a small set of fixed diameters, reported as 16, 19 and 22 cm, together with a model shaped for the female chest (Loufopoulos et al. 2021; Haecker 2016). Choosing between them is a matter of matching the bell to that geometry, not of finding an exact custom dimension. Two people the same age can need different sizes, and one person can sit on the boundary between two. Because the deepest point and the surrounding flat area are things only you can measure on your own body, the size question is answered from measurements, which is where a structured assessment or a clinician comes in.

What the evidence actually shows

The size range that has been studied

Loufopoulos and colleagues (2021) reviewed the vacuum bell literature across 13 studies and described the device as supplied in three diameters, 16, 19 and 22 cm, alongside a model fitted for the female chest. The underlying device design received FDA clearance in 2012. Haecker (2016), reporting one of the largest single cohorts, roughly 450 patients treated since 2003 and aged 2 to 61, described the same structure: three device sizes plus a version made for adolescent and adult female patients. Two decades of clinical use have not expanded that into a fine-grained size chart. The range is deliberately small.

How a size is actually chosen

With only a few diameters available, selection is a matching exercise rather than a calculation. The bell has to be wide enough that its cup spans the whole depression and its centre sits over the deepest point, and no wider than the flat skin that surrounds the hollow, because the rim needs continuous contact to hold a vacuum. A bell that cannot reach the deepest point leaves the part that most needs lifting untouched. A bell whose rim overruns onto curved or bony surfaces breaks its own seal. Between two plausible diameters, the one that keeps a clean rim contact usually suits better. None of this is captured in a validated protocol: Haecker and colleagues (2024) note that no such guidelines exist, which is precisely why sizing is done by measurement and fit rather than by formula.

Why age is not the sizing variable

A common assumption is that a child needs a child-sized bell and an adult an adult-sized one. The cohorts do not support reading it that way. The same three diameters served patients from toddlers to people in their sixties (Haecker 2016). What changes with age is not the catalogue of sizes but which of them happens to fit a given chest, and separately, how the chest responds once treatment starts. Starting age and consistency of use shape the outcome of therapy, but those are questions about whether and how well the chest changes, not about which diameter to buy.

Who this works best for

Good fit is most likely when the indentation is a single, roughly central hollow with a defined deepest point and a rim of flat skin around it, because that is the shape the bell is built to seal against. A chest wall that visibly lifts when the device is applied has met the mechanical precondition the therapy depends on. Younger children tend to suit the smaller diameters and adults the larger, but this tracks the size of the chest and the indentation rather than a rule based on age: Haecker (2016) treated patients from 2 to 61 years old with the same small set of sizes. Loufopoulos and colleagues (2021) list mild to moderate deformity, and patients declining surgery, among the recognised indications, and depth matters more than breadth for the eventual result (Luo et al. 2022). The female-fitted model exists for a specific reason: breast tissue changes where a rim can seal, so a shape designed for the flatter male sternum will not sit correctly on many adult female chests.

Who this does not work for

Sizing cannot rescue a chest the device was never going to seal on. A depression that is broader than the largest available bell has no diameter that both clears its deepest point and rests on firm skin, so no size will hold suction across it. The same is true of a markedly off-centre or asymmetric indentation, where the rim meets bone or an uneven surface on one side and breaks the seal. Skin that is broken, inflamed or affected by active disease over the target area rules out application at any size until it settles. A protruding sternum, pectus carinatum, is the opposite deformity and is managed with compression rather than suction, so no vacuum bell diameter applies to it. And a rigid chest wall that does not visibly lift under the device will not respond regardless of how well the bell fits, because a correct size cannot supply flexibility the cartilage does not have.

What this means in practice

Three things follow from the evidence above.

One: measure the indentation, not yourself. The useful numbers are the width of the sunken area, the position of its deepest point, and the band of flat skin around it. Take them with a ruler, in a consistent posture, before choosing a diameter. A measured chest answers the size question; a guess from age or shirt size does not.

Two: favour a clean seal over a snug span. When a chest sits between two diameters, the one whose rim rests entirely on flat skin is usually the safer choice, because a bell that cannot maintain a vacuum does nothing at all, while a slightly larger clean-sealing bell still lifts the deepest point.

Three: the cost context is worth stating. Surgical repair in the United States commonly runs 40,000 to 70,000 dollars, with uninsured cases reported up to 100,000, and involves a metal bar in the chest for two to three years plus a second operation to remove it. A vacuum bell is a few hundred dollars: device-only products in this category commonly list at 465 to 495 dollars, an unguided marketplace listing runs about 90 dollars, and a complete correction system that adds a brace, skin care, the written protocol and scheduled follow-up costs a few hundred dollars more than the device alone. The size decision sits entirely inside that smaller number, which is part of why getting the fit right is worth the few minutes of measurement it takes.

Not sure whether this applies to you?

The two questions this article cannot answer for you are whether your own chest is a reasonable candidate, and which device size fits it. Both depend on measurements only you can take.

The FormaChest assessment takes about four minutes. It screens your situation against the variables the research identifies as predictive (age, depth of the indentation, chest flexibility and symptoms) and returns an honest read on whether conservative treatment is a reasonable first step. That includes telling you when the answer is to see a surgeon first, which it does for roughly the situations described in the section above.

It also returns a vacuum bell size recommendation based on your own measurements, at no cost.

Sizing is normally not free or simple in this category. The usual process is to email photographs of your bare chest to a company and wait for a reply, or to print paper templates and tape them to yourself, with the manufacturer warning that self-measurement may produce the wrong model. The assessment asks for numbers you can take alone with a ruler. No photographs, no email exchange, no deposit.

Take the free assessment →

What the research does not tell us

The sizes on offer come from device engineering, not from a trial that compared them. Haecker and colleagues (2024) state plainly that after 20 years of clinical use no validated guidelines for the therapy exist, and that absence covers sizing as much as it covers session length. No published study reports how often a self-measured size turns out wrong, how a borderline chest should be assigned between two adjacent diameters, or whether a fractionally larger or smaller bell changes the eventual result. The diameters reported in reviews describe the devices that have been studied, not an optimum derived from outcomes. Depth influences results, with Luo and colleagues (2022, n=139) finding shallower indentations more likely to correct fully, but no work links a specific starting depth to a specific size. These are the gaps that a numbers-only sizing rule would quietly paper over, and they are the reason honest sizing rests on fit rather than on a formula.

About this guide This article is published by FormaChest, a European manufacturer of vacuum bell correction systems, registered in Romania as AUGUMENTUM SRL. We make the device described above, and every figure quoted is cited to its source so you can verify it independently. The fit problem described in this article is the reason FormaChest ships a complete correction system rather than a device alone: the correctly sized vacuum bell, a chest support brace, post-session skin care, the written protocol, and scheduled follow-up. Every competitor in this category sells the device by itself. [See what is included →]Tomas Titus is the founder of FormaChest (AUGUMENTUM SRL, Craiova, Romania). He had pectus excavatum and corrected it without surgery, documenting his own vacuum bell treatment on camera, taking measurements before each session rather than after. His chest depth went from 25mm to 4mm. That is one person's result at 19; published adult timelines run 12 to 24 months and results vary. He is not a clinician, and nothing in this article is a substitute for assessment by one.

Related questions

References

  1. Loufopoulos I, Karagiannidis IG, Lampridis S, Mitsos S, Panagiotopoulos N. Vacuum Bell: Is It a Useful Innovative Device for Pectus Excavatum Correction? Turkish Thoracic Journal. 2021;22(3):251-256. PMID 35110237
  2. Haecker FM. Vacuum bell therapy. Annals of Cardiothoracic Surgery. 2016;5(5):440-449. PMID 27747177
  3. Haecker FM, et al. 20 years clinical application of the vacuum bell for conservative treatment of pectus excavatum. Journal of Thoracic Disease. 2024;16(8):5285-5298. PMID 39268139
  4. Luo D, Cheng K, Yuan M, Xu C, He T. Efficacy and determinants of vacuum bell treatment in preschool children with pectus excavatum. Frontiers in Pediatrics. 2022;10:1008437. PMID 36313864
  5. Scaife ER, et al. Vacuum bell therapy for pectus excavatum. 2025. n=240

This article is for information only and is not medical advice. Pectus excavatum should be diagnosed and assessed by a qualified physician. If you have chest pain, breathlessness, palpitations or reduced exercise tolerance, seek medical assessment before beginning any treatment.

Last reviewed: July 2026.

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