30-40 mmHg compression stockings are for moderate-to-severe venous disease; pair medical guidance with the brand’s exact ankle and calf measurements.
Buying 30-40 mmHg stockings on pressure level alone is the most common mistake people make. This firm range is a medical-grade choice, so the real selection process has two parts: confirming the pressure level fits the condition, then sizing from the leg measurements each brand specifies.
When Is 30-40 mmHg The Right Choice?
30-40 mmHg is a high-level, firm compression range intended for moderate-to-severe venous and lymphatic disease — not ordinary leg swelling or mildly uncomfortable veins. Manufacturer guidance from Sigvaris’s compression level guidance places this band firmly in medical territory.
Typical reasons this range gets prescribed:
- Moderate-to-severe edema or lymphedema
- More serious varicose veins
- DVT recovery and post-thrombotic syndrome
- Active venous stasis ulcers
- Swelling after bone fractures or orthopedic surgery
- Phlebitis, or skin changes where ulcers have already healed
If your symptoms are mild, a lower-pressure garment may be enough. 30-40 mmHg is reserved for disease that lighter compression does not control, and it should be chosen only after the right medical indication and leg measurements are confirmed.
How Do You Measure For Compression Stockings?
You size 30-40 mmHg stockings with a tape measure, not a shoe size. The exact points depend on the garment style, and every manufacturer publishes its own chart for each product line.
| Garment Style | Measurements You Need | Fit Notes |
|---|---|---|
| Knee-high | Narrowest ankle, widest calf | Most common for lower-leg edema and ulcer care; some lines add petite and regular lengths |
| Thigh-high | Ankle, calf, widest thigh, leg length | Thigh circumference drives the size; look for a grip top that stays put without digging in |
| Waist-high | Ankle, calf, thigh, hip, leg length | Usually chosen when swelling reaches the thigh or involves the hip area |
Measure in the morning when swelling is lowest, and follow the chart for that exact model — the same nominal size can differ between brands, and even between styles from one brand. Also confirm whether the product is knee-high, thigh-high, or waist-high, whether you need open or closed toe, and whether a petite, wide, or plus option is offered. If your numbers sit between sizes, the model’s own chart decides the fit; there is no reliable universal conversion.
Once the measurement set is clear, our tested 30-40 mmHg compression stocking picks show which models fit best and hold their compression longest.
Safety Checks And Mistakes To Avoid
High compression can be genuinely harmful in the wrong patient, so a quick safety screen comes before any purchase. People with arterial disease face the highest risk: If arterial disease is suspected, or if you have diabetes or unexplained leg pain, get an ABI measurement before you buy.
Three mistakes cause most failed fittings:
- Choosing by the mmHg number while ignoring the garment’s measurement chart
- Assuming all brands size the same — different models use different circumferences and leg-length rules
- Self-prescribing 30-40 mmHg for mild symptoms that a lighter range would handle
The safe order of operations: confirm the condition genuinely calls for 30-40 mmHg, rule out arterial disease with a clinician if needed, take the measurements that model requires, then order the right style and length. A stocking that fits correctly should feel firm but not painful, and a clinician should check the fit at your first try-on.
FAQs
How tight should 30-40 mmHg stockings feel?
They should feel distinctly firm, with the strongest pressure at the ankle, easing upward. Sharp pain, numbness, or toes that turn cold or blue mean the fit is wrong or the pressure is too high for you. A correct fit is snug but comfortable enough to wear through a full day.
Are 30-40 mmHg stockings safe for flying?
Travel compression is usually a lower pressure range unless a clinician specifically prescribes 30-40 mmHg for a diagnosed condition. For routine long-haul flight swelling, lighter graduated compression is typically the appropriate choice. Ask your doctor which level fits your situation before using firm medical-grade stockings on a trip.
How long do 30-40 mmHg stockings last?
With daily wear and proper washing, most medical compression stockings keep their rated pressure for about four to six months. After that, the elastic gradually loses tension even when the fabric looks fine. Replace them on that schedule, and buy two pairs if you can so you can rotate them.
References & Sources
- Sigvaris. “Compression Levels.” Manufacturer guidance on which conditions match the 30-40 mmHg range.
- Kaiser Permanente. “Compression Stockings Clinical Criteria.” Clinical criteria for prescribing compression hosiery.
- Thrombosis.org (NBCA). “Compression Stockings 101.” Patient guide to how compression therapy works and when it applies.