Bio / Free 25(OH)D3 calculator When you use this calculator please cite the article:Vičič V, Kukec A, Kugler S, Geršak K, Osredkar J, Pandel Mikuš R. Assessment of Vitamin D Status in Slovenian Premenopausal and Postmenopausal Women, Using Total, Free, and Bioavailable 25-Hydroxyvitamin D (25(OH)D). Nutrients. 2022; 14(24):5349. https://doi.org/10.3390/nu14245349Download: https://vidvicic.com/wp-content/uploads/2023/05/nutrients-14-05349-v2.pdf Equations: This free online calculator of Free and Bioavailabile 25(OH)D is based on modified Vermulen equation (Vermeulen, Verdonck, and Kaufman 1999) with exact calculation procedure as provided by Abidin and Mitra (2020). Programmed by: Matic Milavec. email: matic.milavec(at)gmail.com