Anyone can use the following 'live' GISsurfer map to help learn about UTM coordinates. This map with a UTM grid will work in most browsers on most devices including cell phones.
The map is displayed by GISsurfer which is a general purpose web map based on the Leaflet map API (Application Program Interface). GISsurfer features that support UTM coordinates include search, geolocation and link to this map.
As you zoom in the grid will become more detailed. Note that different basemaps let you zoom in different amounts. Use the Menu button to toggle the UTM coordinates grid on/off.
While the map is open you can now display data from *any* public-facing (i.e. no login required) ArcGIS server along with a USNG grid on top of that data. To get started, click the basemap button (next to the 'Menu' button) then under the 'Overlay' heading, click "Add GIS overlays". In the popup that appears, click 'Help'.
For more information about GISsurfer, please visit the GISsurfer homepage.
Up until the middle of 2018 the map on this page was based on the Google map API (Application Program Interface). But that year Google started charging $$$ for its API use on popular web maps that got a high volumn of hits. As a result, the web maps I produce are now based on the free open-source Leaflet map API.
And if you would like a web app for your smartphone that will display your UTM coordinates and the equally important accuracy value, then take a look at FindMeSAR (https://findmesar.com). The "Tips" button has more information about this web app.