Mixed beaches are generally rare worldwide however they are common coastal features along the south coast in the UK and constitute the best natural defence to protect littoral environments against flooding and coastal erosion. To date, only a few investigations have attempted to estimate the LST rate for coarse grain size beaches, using models derived from the CERC equation giving K values of about 8% of those obtained for sandy beaches. In this work an impoundment technique has been applied for the first time on a mixed beach to calibrate the CERC equation using field data. Volumetric estimations from beach profile surveys and wave measurements recorded at the field site, Milford-on-Sea (South UK), are being used to estimate the LST rate, thus enabling model calibration for future shoreline change scenarios.