This document provides guidance on how existing community science beach cleanup initiatives, such as the International Coastal Cleanup (ICC) or the Marine Litter Watch (MLW) can contribute to measuring progress towards Sustainable Development Goal (SDG) indicator 14.1.1b – Marine Plastic Debris Density. The guidelines are helpful for countries wishing to report their volunteer-collected data and were drafted in collaboration with the nonprofit environmental organization Ocean Conservancy, which hosts the annual ICC. The goal metric SDG indicator 14.1.1b is striving to achieve when measuring marine plastic debris density is average count of plastic items per km2. This will be tracked yearly and extrapolated to the national level based on the total area cleaned for each country.