To reach high vaccination rates against COVID-19, children and adolescents should be also vaccinated. To improve childhood vaccination rates and vaccination readiness, parents need to be addressed since they decide about the vaccination of their children. We adapted the 7C of vaccination readiness scale to measure parents’ readiness to vaccinate their children and evaluated the scale in a long and a short version in two studies. The study was first evaluated with a sample of N = 244 parents from the German COVID-19 Snapshot Monitoring (COSMO) and validated with N = 464 parents from the Danish COSMO. The childhood 7C scale showed acceptable to good psychometric properties in both samples and explained more than 80% of the variance in vaccination intentions. Additionally, differences in parents’ readiness to vaccinate their children against COVID-19 were strongly determined by their readiness to vaccinate themselves, explaining 64% of the variance. Vaccination readiness and intentions for children changed as a function of the children's age explaining 93% of differences between parents in their vaccination intentions for their children. Finally, we found differences in correlations of components with self- versus childhood vaccination, as well as between the children's age groups in the prediction of vaccination intentions. Thus, parents need to be targeted in specifically tailored ways, based on the age of their child, to reach high vaccination rates in children. The scale is publicly available in several languages (www.vaccination-readiness.com).