Purpose: Breast reconstructive surgeons still face challenges in accurately measuring breast volume for the development of an individualized surgical plan. 3D surface scanning volumetry is increasingly implemented in clinical practice. Data related to 3D volumetry against MRI considered the ‘gold standard’, is limited. We present a comparative analysis based on one of the largest prospectively collected series of breast imaging of normal subjects. Methodology: Women who underwent Breast MRI as part of a high-risk screening program were recruited. A dedicated study radiologist performed MRI volumetry. 3D volumetric analysis (3DVA) was performed on images captured using both the Vectra Mirror® automatic program and manually to compare intra-methodological variability. Skin thickness below the IMF was measured on MRI images. Results: 106 breasts from 53 women were analysed. Automatic and manual 3DVA showed excellent correlation (ICC 0.887). MRI provided statistically significantly higher volumes than 3DVA (p < 0.001). A linear association between MRI and manual 3DVA volume is demonstrated [MRI=1.61(VECTRA)+23]. On boxplot analysis, the difference between MRI and 3DVA volumes increased in median and IQR, stratified against increasing skin thickness. Similarly, IQR of the difference in automatic and manual 3DVA volumes increased beyond skin thickness >50mm. Conclusion: Automatic VECTRA® XT 3D software volumetry calculator shows a good correlation to manual methods. The linear association between MRI and 3DVA gives confidence for use in clinical practice. At increasing skin thickness, both MRI and 3DVA show greater variability, which may limit their accuracy in patients with thicker subcutaneous tissue, such as patients with higher BMI.