Compression stockings come in pressure levels, and the two you will see recommended most often are 20-30 mmHg and 30-40 mmHg. The numbers matter — they decide how the stocking works, what it is typically used for, and whether your insurance plan will consider covering it. Here is what each level means, and how to tell which one you actually need.
What "graduated compression" means
A medical compression stocking is not equally tight all over. It applies its strongest pressure at the ankle and gradually eases as it moves up the leg — that is what graduated compression means. The pressure gradient works with your calf muscles to help push blood back up toward the heart, instead of letting it pool in the lower leg.
The numbers describe that pressure range in mmHg (millimetres of mercury). A 20-30 mmHg stocking applies between 20 and 30 mmHg at the ankle, with less further up. So 30-40 is not simply "more of a good thing" — it is a firmer therapy, intended for more significant conditions, and noticeably harder to put on.
The levels at a glance
8-20 mmHg — mild, over-the-counter
Light support for tired, heavy legs, long days on your feet, or flight comfort. No prescription needed, and generally not eligible for insurance reimbursement. Browse mild compression if this is you.
20-30 mmHg — moderate, the entry point for medical grade
This is the most commonly prescribed level, and the point where insurers start treating compression as a medical device rather than a comfort item. Manufacturers' own indication lists for 20-30 mmHg garments cover:
- Varicose veins and chronic venous insufficiency (when leg veins struggle to return blood to the heart)
- Swelling and tired, heavy legs
- Congestion problems and edema (fluid swelling) during pregnancy
- Prevention during pregnancy, travel, and long periods of standing or sitting
- Post-surgical and post-sclerotherapy care (sclerotherapy is an injection treatment for varicose and spider veins)
If your doctor has said "compression stockings" without a number, 20-30 mmHg is very often what they meant — but confirm it, because the prescription needs the number for insurance. See the range in 20-30 mmHg moderate compression.
30-40 mmHg — firm
A step up in therapy, typically prescribed rather than self-selected. Manufacturers indicate this level for the same venous conditions in more pronounced form: established varicose veins with swelling, edema that keeps returning, the period after vein procedures, deep vein thrombosis (a blood clot in a deep leg vein) and the post-thrombotic conditions that can follow it. If your clinician has diagnosed a specific venous condition and named this level, shop 30-40 mmHg firm compression.
40-50 mmHg and up — extra firm, clinician-directed
Reserved for severe venous disease and significant chronic swelling, and only ever worn on a clinician's direction. Garments at this level — see extra firm compression — are genuinely difficult to don without technique or aids, and wearing this much pressure without professional advice is not safer than wearing less.
Adjustable compression wraps
One more option worth knowing about: adjustable compression wraps use overlapping bands with hook-and-loop closures instead of a knitted sleeve, covering a wide adjustable range (around 20-50 mmHg). Clinicians often suggest them when swelling changes size through the day, or when a stiff stocking is too difficult to pull on.
Why higher isn't automatically better
It is tempting to reason that if 20-30 helps, 30-40 must help more. Three reasons to resist that:
- Choosing a level is a clinical decision. The right pressure depends on your diagnosis and your circulation, and it should come from your physician, nurse or fitter rather than from a store — including ours. Higher pressure is contraindicated (medically inadvisable) for some people, particularly those with arterial disease, which is exactly what a clinician screens for.
- Wearing it matters. A 30-40 stocking is significantly harder to put on and less forgiving to wear, and a stocking only works while it is on — a firmer one that stays in the drawer does nothing for you.
- Insurance follows the prescription. Canadian extended health plans reimburse the level your prescriber names. Buying a higher level than prescribed does not increase your coverage — how the claim process works is covered step by step in our insurance claim guide and on the Insurance Estimates & Claims page.
Sizing matters more than level
Here is the part that surprises people: a compression stocking only delivers the pressure on its label when it is the right size. Compression garments are sized by your actual leg measurements — ankle and calf circumference at minimum — not by shoe or dress size. Get the size wrong and the pressure gradient is wrong with it: too small and the stocking digs in and rolls; too large and you are not getting the pressure the label promises at all.
Every product page on our site carries the manufacturer's own size chart under Size & Fit. Measure first thing in the morning, before any swelling builds up, and read our step-by-step measuring guide before you order. If you are between sizes, message us first — we would much rather spend five minutes on your measurements than have the wrong garment turn up at your door.
Same level, different garments
Whatever level you land on, it comes in every garment style: knee high socks for swelling and symptoms below the knee, thigh high stockings when varicose veins or swelling reach above it, pantyhose for full-leg coverage, and maternity pantyhose cut for pregnancy. The level is a medical decision; the style is mostly about where your symptoms are and what you will comfortably wear.
mediven Vitality Knee High 15-20 mmHg Compression Socks15-20 mmHg
mediven Vitality Knee High 20-30 mmHg Compression Socks20-30 mmHg
mediven Vitality Knee High 30-40 mmHg Compression Socks30-40 mmHg
Circaid Juxtalite HD 20-50 mmHg Adjustable Compression Wrap20-50 mmHg wrap
The short version
- 8-20 mmHg — everyday comfort and travel; buy without a prescription.
- 20-30 mmHg — the standard medical-grade starting point: varicose veins, mild edema, pregnancy, prevention. Where insurance coverage typically begins.
- 30-40 mmHg — firm therapy for pronounced venous conditions and post-procedure care, on a clinician's advice.
- 40-50+ mmHg — severe conditions only, always clinician-directed.
Still deciding? Browse the whole range by compression level, or ask us through the chat button at the bottom-right of any page. We can talk you through the options — and for the level itself, when in doubt, ask your doctor to write it on the prescription.
This article is general education, not medical advice. Compression level is a clinical decision — confirm yours with a physician, nurse or fitter, especially if you have diabetes, arterial disease or reduced sensation in your legs.