--- title: How Do I Convert Respiration Data (Arbitrary Units) Into Volume (mL)? description: You need to understand that our respiration loops calculate the movement of the rib cage during the inspiration and expiration events. Therefore, the raw respiration data is measured in arbitrary unit --- [Skip to content](https://support.hexoskin.com/how-do-i-convert-the-respiration-data-in-arbitrary-units-into-volume-ml#main-content) - [English](https://support.hexoskin.com/how-do-i-convert-the-respiration-data-in-arbitrary-units-into-volume-ml) - [Français](https://support.hexoskin.com/fr/comment-convertir-les-données-de-respiration-en-unités-arbitraires-en-volume-ml) English Show submenu for translations [More support](https://support.hexoskin.com/kb-tickets/new?hsLang=en) [![Hubspot - Hexoskin Logo - Rectangle](https://support.hexoskin.com/hubfs/Hubspot%20-%20Hexoskin%20Logo%20-%20Rectangle.svg)](https://support.hexoskin.com/?hsLang=en) Open main navigation Close main navigation - - [English](https://support.hexoskin.com/how-do-i-convert-the-respiration-data-in-arbitrary-units-into-volume-ml) - [Français](https://support.hexoskin.com/fr/comment-convertir-les-données-de-respiration-en-unités-arbitraires-en-volume-ml) English Show submenu for translations - [More support](https://support.hexoskin.com/kb-tickets/new) - [Contact us](https://support.hexoskin.com/kb-tickets/new) [Contact us](https://support.hexoskin.com/kb-tickets/new?hsLang=en) How can we help you? - There are no suggestions because the search field is empty. 1. [Hexoskin Support Community](https://support.hexoskin.com/?hsLang=en) 2. [Hexoskin FAQ](https://support.hexoskin.com/hexoskin-faq?hsLang=en) 3. [Frequently Asked Question for the Hexoskin community](https://support.hexoskin.com/hexoskin-faq?hsLang=en#frequently-asked-question-for-the-hexoskin-community) # How Do I Convert Respiration Data (Arbitrary Units) Into Volume (mL)? ## Hexoskin’s raw respiratory data is measured in arbitrary units based on ribcage movement. To convert this data into volume (mL), a formula and calibration procedure using a spirometer are required. Hexoskin measures ribcage movement during breathing, and the respiration data is expressed in **arbitrary units**. To convert it to volume in mL, use this formula: `Volume (mL) = ΔRespiration × 13.28 × (Weight / 65)` To obtain **absolute values**, a calibration step is required using a **spirometer**. This involves recording a forced expiration with both the spirometer and Hexoskin at the same time. The volume measured by the spirometer is matched to the Hexoskin signal amplitude to calculate a personal conversion factor. While Hexoskin provides precise data, accuracy varies between users. 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