The 14C marine reservoir age in the North Atlantic and Norwegian Sea has varied through the late glacial period. Here I present a curve, called Norcoast25, for the calibration of late glacial and Early Holocene marine 14C ages from the Norwegian coast. I also present a table of ΔR values that could be used for the calibration of 14C ages with Marine20. The results are based on paired 14C dates of terrestrial plant fragments and articulated marine shells found in shallow marine deposits on the outer coast of Western Norway. The shells calcified in marine water and the 14C reservoir ages represent the surface water off the Norwegian coast. The ΔR value relative to Marine20 decreases from + 300 14C yr at 14.4 cal ka BP to − 100 14C yr at 14.2 cal ka BP and is constant throughout the Allerød. At the transition to the Younger Dryas (YD) the ΔR value increases, and reaches a maximum in the middle YD of + 80 14C yr. At the YD/Early Holocene boundary, the ΔR value drops 200 14C yr. These late glacial ΔR values from Norway’s west coast are 150–300 14C yr lower than has been reconstructed from 14C-dated sediment cores from the open ocean. The Norcoast25 calibration curve can be uploaded to the OxCal calibration program. A link to the file (Norcoast25.14c) is provided at the end of the paper.