Some of my hoses come with no washers.

My rubber garden hose is spraying all over the place, from both where its connected to the water line and where it’s connected to the sprayer. I don’t seem to have a tight seal. I imagine I need to put in some washer or gaskets, but I don’t know which ones or which size.

Is there a standardized size for garden hose washers and gaskets? Where can I find them in a hardware store?