> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sonohealth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Choosing the Right Blood Pressure Cuff Size for Accurate Readings

> Why cuff size is one of the biggest causes of inaccurate home blood pressure readings, how to measure your arm, and how to get a proper fit.

The single most overlooked cause of inaccurate home readings is the wrong cuff size. Getting the fit right is one of the easiest ways to trust your numbers.

<Note>
  A correctly fitted cuff matters as much as the monitor itself. The SonoHealth [BPpro](/blood-pressure/overview) is an upper-arm monitor — measure your arm to confirm the cuff range fits before relying on readings.
</Note>

## Why does cuff size affect accuracy?

A cuff that's **too small** squeezes harder and can read falsely **high**, while a cuff that's **too large** can read falsely **low**. Because the cuff is what actually senses your pressure, an ill-fitting one undermines an otherwise accurate monitor.

## How do I measure my arm for a cuff?

Wrap a flexible tape measure around the midpoint of your bare upper arm, halfway between the shoulder and elbow. Compare that circumference to the cuff's labeled range. If you're between sizes or near the edge of the range, check the manufacturer's guidance.

## How should a cuff fit?

Position the cuff on a bare upper arm, snug but not tight — you should be able to slip one or two fingers underneath. Rest your arm so the cuff sits at heart level, and keep still and quiet during the reading. See the full [measurement technique guide](/blood-pressure/how-to-measure-at-home).

## Upper-arm vs wrist cuffs

Upper-arm monitors are generally preferred for accuracy, while wrist monitors are more position-sensitive. If you use a wrist device, follow its positioning instructions carefully — read our [upper-arm vs wrist comparison](/blood-pressure/upper-arm-vs-wrist) for the tradeoffs.

## Sharing a monitor across different arm sizes

If several people in a household share one monitor, make sure the cuff range covers everyone's arm. Where arm sizes differ a lot, a different cuff size may be needed for accurate readings for each person.

***

**Related:** [How to Measure at Home](/blood-pressure/how-to-measure-at-home) · [Upper-Arm vs Wrist Monitors](/blood-pressure/upper-arm-vs-wrist) · [Why Readings Vary](/blood-pressure/white-coat-hypertension) · [Blood Pressure Overview](/blood-pressure/overview)