Migration has become a key factor in the growth and replacement of populations. But demographic tools for its analysis remain simple. This paper is our response to those problems. We propose a set of simple, single-number indicators, which summarise the aggregate effect of the major contributing factors to the reproduction of populations. Our estimates imply that the persistence of rates observed since 2004 would lead to robust population growth in the North-Western and Northern economically developed European countries. On the other hand, countries in the East of the EU and Central European countries would face substantial population decline due both to their low fertility and to low or negative net migration. If current inflows and fertility levels persist, then within 50 years, people who migrated after 2004 and their descendants will comprise more than half of the population at childbearing and younger ages in some European countries. Copyright © 2013 John Wiley & Sons, Ltd.