Ultra Mobile coverage review
Ultra Mobile is a small GSM service provider that operates on the T-Mobile network. With that, you should not expect Ultra Mobile’s coverage to be better than T-Mobile’s; however, it can be just as good.
Ultra Mobile Coverage Map

I think Ultra Mobile has better coverage than most prepaid providers based on my personal experience as a customer and SIM card distributor for many prepaid providers. I have also noticed that most of the clients I opened accounts for were generally satisfied with Ultra Mobile.
On the flip side, Ultra Mobile’s coverage strength is nowhere near Verizon’s and fractionally weaker than AT&T’s coverage, but you pay a lot less with Ultra Mobile, and it also has hard-to-pass-up promotions.
Ultra Mobile supports 5G and 4G LTE speeds on all its plans. If your phone supports 5G, you can serve the web on Ultra Mobile’s network at full speed.
Coverage Map: Use Ultra Mobile's interactive coverage map to get an idea of its coverage strength in your area.
In the input bar, type in your zip code, and the map will zoom into your location. A dark green shaded area is an indication of good coverage.

The above image shows that I will experience 5G and 4G LTE speeds during my travels in the Las Angeles area.
Note that having too many running apps can cause your phone to operate slower than usual. Ultra Mobile suggests that you “always turn your device off for 10 minutes every week to let it reset and clear memory. Turn off background apps that run in the background that are not critical.”
Comparing Ultra Mobile’s coverage to Boost Mobile’s
Another way to know if Ultra Mobile has good coverage is to compare its coverage map to another provider’s maps.
Below is a comparison of Boost Mobile’s coverage map and Ultra Mobile’s map. Both maps are zoomed in on my selected areas.

Boost Mobile coverage in Tulare county VS Ultra Mobile coverage in Tulare county

Both maps show coverage in my selected areas, but Ultra Mobile has high-speed data in all my routes.
Keep in mind that each service provider has advantages over others in some areas. For example, T-Mobile has decent coverage in California compared to Verizon and AT&T but excellent coverage in New York. Ultra Mobile's coverage map proves that true, but I have also experienced that personally on one of my trips to New York.
Please refer to the latest coverage map on each service provider's website for accurate coverage.