8 Practical Tips for Accurate Home Blood Pressure Monitor Use

2. Check cuff size and fit properly

The cuff must match your upper-arm size. Measure around the widest part of the bare upper arm with a tape. The correct cuff typically covers about 80% of the arm circumference and sits roughly 2 cm above the elbow crease. Using a cuff that’s too small can raise readings by a large margin; research reports errors up to 10–40 mmHg from a poor fit. Many monitors come with "medium" cuffs that suit average adults, but larger or smaller arms need alternate sizes. If you care for elderly family members, measure their arms too — age and body changes affect cuff choice. When placing the cuff, make sure it’s snug but not tight, and that the tubing runs down the arm toward the wrist. Always put the cuff on bare skin, not over fabric, because even thin clothing can alter results. If a manufacturer's replacement cuff is available locally, keep one as a spare so you can avoid improvising with an ill-fitting band.