Time to leave the bars
The number of bars on your phone?
Not the best way to measure cell phone signal strength.
Think of it like cooking without using measuring cups and spoons. Sure you can eyeball everything and get a decent meal, but when you want to produce the same reliable results, you need to get accurate.
And cell phone bars are not accurate. Why?
They're SUBJECTIVE across all carriers and phones!
In plain English, it's up to each individual carrier or phone manufacturer to decide what's 1,2, 3, or full bars on their own service. So what could be 1 bar on Verizon, might be 2 bars on AT&T, 3 bars on Sprint, and 4 bars on T-Mobile.
There is no industry standard that ties cell phone signal strength to the number of bars on your phone. Even the difference between 4G and LTE is murky to most people.
But there is the one true method.
Say hello to my decibel friend
Cell phone signals are radio waves, the AM/FM kind, that operate within a certain frequency. They are measured within the following strength ranges:
- 50 decibels to -120 decibel-milliwats (dBm).
-50 dBm is great signal or full bars. -120 dBm is very poor signal or a dead zone.
This is true for all cellular devices in North America and true for all carriers from AT&T to even local carriers.
So understanding how to find & read dBm on your phone is much more accurate than the number of bars.
Let's look at finding dBm values on your phone:
For iOS Users
Starting with iOS 11 and 12, Apple has hidden dBm readings in iPhone field test mode. However, depending on your iPhone chipset (Intel or Qualcomm) and your carrier (Verizon, AT&T, T-Mobile, or Sprint), there’s a slim chance to find your dBm readings through this workaround.
iPhone with Intel chipset (iOS 11, iOS 12, iOS 13, and iOS 14)
iOS 14 pictured
- Dial *3001#12345#*
- Tap LTE on iOS 11-13, or the Menu on iOS 14
- Tap Serving Cell Meas
- Your dBm is read as rsrp0.
iPhone with Qualcomm chipset (iOS 11 & 12)
- Dial *3001#12345#*
- Tap 1xEV-DO.
- Your dBm is read as RX AGC0.
For any iPhone pre-iOS 11
- Dial *3001#12345#*
- Swipe down notifications bar.
- Your dBm is in the upper left-hand corner of the screen.
If you’re unable to find any of these options during your field test mode process, you most likely have an incompatible carrier and chipset. The next best method is performing a speed test around areas inside and outside your home. But once we crack the code on dBm readings on your iPhone, we’ll update as soon as possible.
For Androids Users
Field test mode on Android varies by phone model and Android OS version. However, it is generally found under the Settings menu.
- Tap Settings
- Tap About Phone
- Tap Status or Network
- Tap SIM Status
- Your dBm is under Signal strength
Once you have your dBm reading through field test mode or app, walk around inside and outside the perimeter of your home. Make note which areas get the best dBm reading. This shows you the general direction of your cell tower and which rooms inside your home have the best reception.
For Blackberry Users
- Access Settings.
- Select Device.
- Select Device Status.
- Select Network Info.
- Then you'll see dBm reading.
For Other Users
Ok, so now you have access to dBm readings. What's next?
It's recommended you walk around the outside of your home or property. dBm readings take from a few seconds to half a minute to refresh, so walk slowly.
Find out which area consistently is closest to -50 dBm.
By doing this, you find out two things: your best dBm reading and the area of your home which gets the best signal.
Now let's decipher what good signal is in terms of dBm.
Please note this is an educated but general assumption. The following chart is not true for all carriers, because each carrier has their own standard for dBm to bars. Let's get started.
If your outside signal ranges from:
- -50 to -79 dBm, then it's generally considered great signal (4 to 5 bars).
- -80 to -89 dBm, then it's generally considered good signal (3 to 4 bars).
- -90 to -99 dBm, then it's generally considered average signal (2 to 3 bars).
- -100 to -109 dBm, then it's generally considered poor signal (1 to 2 bars).
- -110 to -120 dBm, then it's generally considered very poor signal (0 to 1 bar).
So what's your best dBm value?
What to do if your dBm reading is over -100?
Generally from -95 dBm and above, you're dealing with below average signal. However, at -100 dB, that's when you're experiencing some serious inconsistent service and weak reception.
Here are some posts we've written that can help:
- 13 Best Ways To Improve Your Cell Phone Signal
- AT&T Signal Booster
- Verizon Signal Booster
- T-Mobile Signal Booster
- Sprint Signal Booster