Johnson County, IA Cell Phone Coverage Map & Network Rankings (2026)

Find the best cell phone network and plan to use in Johnson County, IA

Coverage rankings for Johnson County, IA

T-Mobile currently ranks first for coverage in this area, with a coverage score of 91.4. Compare Wireless Carriers uses FCC broadband map data to estimate and calculate coverage scores. More on that further below.

RankCarrierScoreOverall4G LTE5GFast 5GAverage Signal
1T-Mobile91.495.7%95.7%88.7%73.5% -88 dBm
2Verizon72.899.0%99.0%40.4%26.8% -93 dBm
3AT&T62.992.5%92.3%35.8%22.8% -111 dBm

Scores include coverage area, network type, and average signal strength.

Cell phone coverage map for Johnson County, IA

Zoom in for local detail. Tap or click a colored area to see coverage and signal details. On mobile, use two fingers to move the map.

Coverage Key
Less covered More covered
Darker areas mean the carrier covers more of that location.

Map data © OpenStreetMap contributors, © CARTO. Rendered with MapLibre. FCC BDC mobile coverage processed by Compare Wireless Carriers.

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Cell phone coverage by network in Johnson County, IA

#1

T-Mobile

Coverage Score 91.4
In Johnson County, IA
Overall
95.7%
4G LTE
95.7%
5G
88.7%
Fast 5G
73.5%
Average Signal -88 dBm
#2

Verizon

Coverage Score 72.8
In Johnson County, IA
Overall
99.0%
4G LTE
99.0%
5G
40.4%
Fast 5G
26.8%
Average Signal -93 dBm
#3

AT&T

Coverage Score 62.9
In Johnson County, IA
Overall
92.5%
4G LTE
92.3%
5G
35.8%
Fast 5G
22.8%
Average Signal -111 dBm
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Coverage by city in Johnson County, IA

Cities and towns are shown for county-level comparison. Coverage percentages use land-area only coverage.

CityVerizonAT&TT-Mobile
Coralville, IA 100.0% 100.0% 83.2% 72.8% -85 dBm 100.0% 97.5% 97.8% 76.9% -102 dBm 100.0% 100.0% 99.4% 94.6% -80 dBm
Frytown, IA 100.0% 100.0% 60.0% 0.0% -104 dBm 75.0% 75.0% 55.0% 15.0% -118 dBm 100.0% 100.0% 100.0% 100.0% -62 dBm
Hills, IA 100.0% 100.0% 0.0% 0.0% -85 dBm 100.0% 100.0% 57.1% 57.1% -114 dBm 100.0% 100.0% 100.0% 100.0% -67 dBm
Iowa City, IA 100.0% 100.0% 78.9% 62.8% -87 dBm 100.0% 100.0% 72.1% 54.9% -106 dBm 100.0% 100.0% 100.0% 97.2% -81 dBm
Lone Tree, IA 100.0% 100.0% 0.0% 0.0% -98 dBm 92.0% 92.0% 12.0% 0.0% -119 dBm 100.0% 100.0% 100.0% 100.0% -70 dBm
North Liberty, IA 100.0% 100.0% 98.7% 95.8% -80 dBm 100.0% 100.0% 94.5% 68.8% -111 dBm 100.0% 100.0% 100.0% 99.6% -80 dBm
Oxford, IA 100.0% 100.0% 72.7% 50.0% -93 dBm 100.0% 100.0% 40.9% 40.9% -106 dBm 100.0% 100.0% 100.0% 100.0% -83 dBm
Shueyville, IA 100.0% 100.0% 29.2% 16.7% -88 dBm 100.0% 100.0% 20.8% 20.8% -102 dBm 100.0% 100.0% 100.0% 100.0% -79 dBm
Solon, IA 100.0% 100.0% 9.5% 7.1% -77 dBm 100.0% 100.0% 4.8% 2.4% -105 dBm 100.0% 100.0% 100.0% 100.0% -71 dBm
Swisher, IA 100.0% 100.0% 0.0% 0.0% -70 dBm 100.0% 100.0% 43.5% 43.5% -106 dBm 100.0% 100.0% 100.0% 100.0% -77 dBm
Tiffin, IA 100.0% 100.0% 100.0% 93.6% -81 dBm 100.0% 100.0% 90.8% 72.5% -113 dBm 100.0% 100.0% 100.0% 100.0% -79 dBm
University Heights, IA 100.0% 100.0% 50.0% 33.3% -93 dBm 100.0% 100.0% 100.0% 83.3% -118 dBm 100.0% 100.0% 100.0% 100.0% -87 dBm
Cedar Rapids, IA 100.0% 100.0% 80.2% 70.2% -83 dBm 98.1% 96.9% 81.2% 48.8% -109 dBm 99.6% 99.6% 98.4% 93.4% -81 dBm
West Branch, IA 100.0% 100.0% 3.0% 0.0% -81 dBm 100.0% 100.0% 0.0% 0.0% -101 dBm 100.0% 100.0% 100.0% 100.0% -72 dBm

About The Coverage Data

Coverage and signal estimates are derived by Compare Wireless Carriers from carrier-reported data in the FCC’s National Broadband Coverage Map, last updated in June 2025. “Percent covered” shows how much of the city or ZIP code area has a carrier signal, whether weak or strong. Signal bars show the estimated average signal strength in areas of Johnson County, IA where that carrier has coverage.

If a carrier says you should have service but you do not, run a challenge test with the FCC Mobile Speed Test App. The FCC uses those results to check carrier-submitted coverage data and requires a carrier response when enough tests show a pattern of inaccurate coverage reporting.