How Different Countries Measure Medical Compression — and How to Compare Them Correctly
If you’ve ever shopped for medical compression socks or stockings, you’ve likely seen two different rating styles: some products are labeled in mmHg, while others use Class I, II, or III. The goal is the same (graduated compression), but the way it’s measured and labeled can vary by region.
This guide breaks down what those ratings mean, how to compare them across brands, and why “equivalent” compression can look different on the label depending on where the product is certified.
What does mmHg mean?
mmHg (millimeters of mercury) is a unit of pressure. In medical compression garments, it typically refers to the amount of pressure applied at the ankle, where compression is strongest before gradually decreasing up the leg (graduated compression).
| Common Label | Typical Range | Plain-language description |
|---|---|---|
| Wellness / Light Support | Below 15 mmHg | Everyday comfort support; often used for travel or long days on your feet |
| Mild | 15–20 mmHg | Entry-level medical compression; common for first-time wearers |
| Moderate (sometimes referred to as “firm”) | 20–30 mmHg | Stronger everyday medical compression; often chosen by experienced wearers |
| High (sometimes referred to as “extra-firm”) | 30–40 mmHg | High compression; typically worn with clinical guidance |
| Very High | 40+ mmHg | Specialist compression; commonly used for advanced clinical needs |
Note: Ranges may vary slightly by manufacturer and standard; mmHg values are typically specified as a range rather than a single exact number.
On our site you may see compression grouped as Mild (15–20 mmHg), Moderate (20–30 mmHg), and High (30–40 mmHg). Some manufacturers and medical references use the word “Firm” for the 20–30 mmHg category and “Extra-firm” for 30–40 mmHg. These labels describe the same compression ranges — only the wording differs.
What are compression classes?
In much of Europe, medical compression is often labeled using a Class system (Class I–IV). Instead of printing one mmHg number, the label indicates an approved pressure range measured at the ankle.
| Compression Class | Approx. mmHg Equivalent | What it generally means |
|---|---|---|
| Class I | ~15–20 mmHg | Milder medical compression |
| Class II | ~20–30 mmHg | Moderate medical compression (often described as “firm”) |
| Class III | ~30–40 mmHg | High compression (often described as “extra-firm”) |
| Class IV | 40+ mmHg | Very high compression (specialist) |
Standards by country & certification body
Compression standards define how pressure is measured and what ranges qualify for each rating. This is why two products can feel similar while showing slightly different numbers or class labels.
| Region / Standard | Common Labeling | Typical Pressure Ranges (Ankle) |
|---|---|---|
| Canada & United States | mmHg |
Common consumer ranges:
|
| Germany — RAL-GZ 387 | Class I–IV |
|
| European Union — CEN (EN standards) | Class I–IV |
Often aligned with German-style class ranges (varies by manufacturer).
|
| United Kingdom — BSI | Class I–III |
|
| France — ASQUAL | Class I–IV |
|
| Switzerland | Class I–IV |
Often aligned with German-style class ranges (varies by manufacturer).
|
Quick reference: Class → mmHg
≈ 15–20 mmHg
≈ 20–30 mmHg
≈ 30–40 mmHg
≈ 40+ mmHg
Use this as a practical starting point when comparing European class-labeled products to North American mmHg-labeled products. Note, there is overlap, for example, a 20-30 mmHg product can be labelled as Class I depending on where and how it was tested.
Quick comparison chart
This quick reference aligns OrthoMed’s on-site labels with common international class systems. Because regional standards can overlap, equivalences are shown as approximate.
| OrthoMed site label | mmHg range | Common EU/Germany label | UK (BSI) approx. | France (ASQUAL) approx. |
|---|---|---|---|---|
| Mild | 15–20 mmHg | Class I (often overlaps) | Class I (upper end overlaps) | Class II (often begins ~15) |
| Moderate (sometimes “firm”) | 20–30 mmHg | Class II | Class II | Class II–III (overlap) |
| High (sometimes “extra-firm”) | 30–40 mmHg | Class III | Class III (upper end overlaps) | Class III |
Note: “Approx.” and “overlap” reflect real differences in regional test methods, tolerances, and class boundaries.
Why the numbers don’t always match perfectly
If you compare charts across countries, you may notice slight differences in ranges. That’s normal. Different standards can vary in:
- How pressure is measured at the ankle (test method)
- Allowed tolerances for manufacturing variation
- How class boundaries are defined (range cutoffs)
The practical takeaway is that you should compare compression by category and intended use (mild vs moderate vs high), not by chasing one “perfect” number across standards.
How Major Compression Brands Apply These Standards
While charts and equivalence tables are helpful, real-world labeling often depends on how a product is tested, certified, and approved under a specific standard. This is one reason why some 20–30 mmHg products sold in North America may be labeled as Class I under European systems.
This can show up across several leading medical compression brands:
- Medi — Many Medi products that are marketed as 20–30 mmHg in North America are certified as CCL I under European standards.
- Bauerfeind — Similarly, Bauerfeind’s medical compression stockings in the 20–30 mmHg range are often labeled as CCL I due to how the applicable standards define Class I.
- Sigvaris — Depending on the product line and market, Sigvaris may show mmHg ranges, Class labels, or both, reflecting the certification used.
- Juzo — Juzo products frequently emphasize European Class labeling, which can make North American equivalents appear “lower” on paper despite comparable performance.
- Jobst — Jobst products are often labeled primarily in mmHg, but equivalence to European classes can vary by market and certification.
The key takeaway is that brand certification matters. Two products can deliver similar graduated compression while carrying different class labels, depending on the standard under which they were tested.
How OrthoMed Canada labels compression
To make comparison shopping easier, we aim to present compression information clearly:
- We show mmHg where the manufacturer provides it.
- We include Compression Class when that’s how the product is certified/labeled (common with European brands).
- We use plain-language groupings (wellness / mild / moderate / high) where helpful.
FAQs
Is Class II the same as 20–30 mmHg?
Often, yes. In practical terms, European Class II commonly aligns with North American 20–30 mmHg. Sometimes 20-30 mmHg products can be labelled as Class I as well. Exact ranges can vary slightly by standard.
Why do European products use classes instead of mmHg?
Many European standards are historically class-based and define approved ankle-pressure ranges for each class, rather than printing a single mmHg value on every package.
Why do charts look different between Germany, the UK, and France?
Different standards can use different test methods, tolerances, and class boundaries. A reliable approach is to compare by category (mild vs moderate vs high) and follow professional guidance when applicable.
What if I’m between two compression levels?
Comfort and fit are key. If you’re unsure, starting lower can help you wear compression consistently—then adjust if needed. Our team can help interpret labels across brands.
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