Use Field Test Mode to See True iPhone Signal Strength as Numbers Instead of Bars

Aug 20, 2012 - 71 Comments

iPhone cell signal bars are shown as numbers rather than bars with Field Test mode

Field Test Mode is a hidden feature on the iPhone which allows you to see technical details of the device, the most useful of which is the true cell signal strength displayed as a number rather than the traditional signal bars or dots. We’ll show you exactly how to enter Field Test Mode, as well as how to enable Field Test Mode all the time to be able to see the real cellular signal from your iPhone represented as numbers in the upper left corner. Of course, we’ll also show you how to read the numbers so that you can understand what a good cell signal looks like versus a bad signal reception. It only takes a minute or two to complete the process, and it’s easy to revert back to normal signal indicators if you decide you’d rather not see the numbers anymore, so even though it’s a bit of iPhone geekiness, try it out!

Entering Field Test Mode on iPhone

This will work on any iPhone model and any version of iOS, except the very original:

  • Open the Phone app as if you were going to make a regular phone call
  • From the iPhone keypad, dial *3001#12345#* and hit the “Call” button

Enter Field Test Mode on iPhone by dialing these numbers

You will immediately see the signal numbers in the upper left corner, and you can tap around the menus to discover other random features and information that is generally meaningless outside of cell technicians and field operators. If you hit the Home button you’ll quit out of Field Test and the signal indicator will return to dots or bars rather than the signal numbers, but it’s easy to always see the numbers too as described below.

Enabling Signal Number as Reception Indicator Rather Than Signal Bars / Dots

To always see the signal numbers rather than the signal bars or dots, you’ll use the Force Quit app function to kill Field Test when it’s open:

  • Dial *3001#12345#* and hit “Call” if you haven’t done so already to launch Field Test
  • Now hold down the Power button until the “Slide to Power Off” message appears, then release the Power button and hold the Home button until Field Test quits
  • Tap the signal bars or signal numbers to switch between the two

To remove the tap-to-switch signal indicator ability, you can either reboot the iPhone or go back into Field Test and close out of it as usual.

In the newest versions of iOS, Field Test Mode transforms the signal ‘dots’ into the signal numbers instead, otherwise the feature is exactly the same:

Field Test Mode on an iPhone

How to Read the Field Test Signal Indicator Numbers

The numbers don’t follow a scale that makes much sense to normal people, but the lower the number (in other words, the more negative) the worse the signal, and the higher the number (less negative) the better.

  • Anything above -80 is good, and would be considered full bars
  • Anything below -110 is bad, and would be considered few bars

For example, a signal number of -105 is considerably worse than a signal of -70. You’ll generally find that anything approaching -105 or lower is fairly bad reception, while anything above -80 is usually good, and if you tap the number signal it’s usually shown as full bars. The full range of the signal numbers extends from -40 to -120, with -130 being a nearly impossible number to see because it means no reception, and -40 would be about the strength you’d get being right alongside a cell tower. Technically, the number goes all the way to -140, but you will almost never see that because it basically means there is no signal to speak of, and most users will see -120 or -130 before it switches over to the “No Service” indicator instead.

Once you get the hang of reading the numbers, you’ll find it’s much more accurate, and it becomes easier to predict when you may drop a call or start to get a bad signal or connection, which creates the weird artifacts and sounds on phone calls, often before it starts to cut out or even drop completely. That typically starts happening around -110 or so, before dropping the connection or call completely if it hits -120 to -130.

If you’re having any problems getting this to work, or you want to see how to do this yourself before jumping in, watch the video below:

This is actually a fairly old hidden feature that works on any iPhone running iOS 4.1 or later, and yes that includes iOS 7.1.1 and beyond, but we’ve had a lot of questions about it recently due to several recent iPhone tip screenshots showing the signal numbers. Basically all of us here at OSXDaily have these signal numbers shown full time on our phones for a variety of reasons, and so you will commonly see them in articles around here.

You can click the image below to detail instructions further, this demonstrates the feature being enabled in iOS 7.1 on an iPhone 5s:

How to Enable Field Test Mode on an iPhone

For those who use Personal Hotspot often, or just for the geekier folks among us, it can be fun to test the mobile download speeds using apps like Speed Test with these signal numbers visible, because it can help to find optimal signal locations and device placement for the best possible speeds.


Related articles:

Posted by: William Pearson in iPhone, Tips & Tricks


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  1. Sam says:

    Doesn’t work in 11.1 (15B93)
    Numerical value a lot better than idiot light bars.
    Don’t dumb it down on the smartest OS.
    Do the right thing and fix it.

  2. Dave says:

    Just updated to iOS 11 and as the others stated, this will not work. Any solution yet?

  3. Patsy says:

    Would like to get rid of the icon that’s a circle with lock in the center at the top of my screen

  4. Cory says:

    Mod broke for IOS11. Perhaps due to them bolding the font for the signal bars? Help!

  5. Barbara Krueger says:

    Sure hope that you can figure out how to have this work in iOS 11 as I much prefer this to the bars. So much more useful for indicating the connectivity when in areas where it varies.

  6. Francisco Reyes Rabell says:

    This doesn’t work on ios11. Any clue?

  7. Tom McElvy says:

    Hey! This has been a wonderful mod, but to let everyone know, iOS V11 broke this. I can still get into Field Test Mode as described above, but the Signal Strength indicator remains as bars. It does not toggle. Hope you all can figure it out, as this was a great mod!

  8. Hmm says:

    In iOS 10+ one can’t disable the field test mode numeric signal strength indicator.

    Also, for clarity the following should be explained:

    Anything BELOW -80 is good, eg. -60 and would be considered full bars
    Anything ABOVE -110 is bad eg. -115, and would be considered few bars

  9. Jim Sherlock says:

    P.S. my cell tower is about 400 yards away.

    • Hmm says:

      it’s not necessarily the closest cell tower but the one with the best signal. your cell tower might be congested.

      Also, if you disable LTE data, you will find you will get a better signal strength.

  10. Jim Sherlock says:

    I’ve got a bit of a problem with this explanation. Where I live I routinely see numbers between -112 and -135 on my iPhone 6, yet I’ve never had a problem making or receiving a call and I don’t think I’ve ever experienced a dropped call. My phone is reading -118 right now for example and I just got off a 15 minute call and had no difficulty at all. What gives?

    • Hmm says:

      And just to add, the iphone does a pretty good job of “holding” onto a weak signal. That I find sucks when I am using data because the speeds will be poor.

  11. Hopman says:

    My phone shows -110 but i have full bars? Is that because im connected to wifi

  12. Colin says:

    I jailbroke a phone years ago. Even though I have upgraded phones and upgraded software many times my cell signal and wifi signal are still shown in dB. I have never sorted out why. I have always upgraded phones by doing a restore onto my new phone from my old phone.

  13. Brendan says:

    I use my cell phone at home frequently so I have AT&T microcell to boost my poor signal. Works well for several years, but recently I’m seeing poor signal quality in phone conversations yet I show 4-5 bars. Looking the numbers, sitting next to my MicroCell I have -64 to -71, and if I walk to far side of house it degrades to -85. I don’t know what the sampling frequency is for this so how I might use it to identify during a phone call that my quality has degraded and I should perhaps wait to talk or try to move to get a better signal.

  14. SSpeer says:

    Is there a way to check the Bluetooth signal put out by an iPhone (6 Plus, iOS 9.1)?

  15. Jo says:

    Thanks Najam! It worked for me I was able to get back to the regular bars

  16. Adam says:

    used this frequently in the UK as I live in a poor signal strength area… however after downloading OS 9.0 for my iPhone 5 last night discovered to my horror that the system now shows “back to phone” instead of the strength as before. Why have Apple screwed this up???

  17. Michael says:

    How do I identify the cell tower I am connected to on an iPhone 6?

  18. Michael says:

    How do I identify the cell tower that I am connected to?

    • Paul says:

      Cellular towers are typically identified in rather weird formats that aren’t particularly user friendly, either in hexadecimal or as a string like “212:28:521”, it’s not meant to be an end-user facing experience as it’s typically cell company technicians who need to use the data. Each company has a different means of interpreting their cell tower ID as well.

      Perhaps the easiest way to find a connected cell tower with iPhone Field Test Mode is to access the data points from FTM and then plug them into a web app like Cell2GPS:

      * Enable Field Test Mode on iPhone as described above in the article:

      * Use the various menus within Field Test Mode to locate and notate MCC, MNC, Network, LAC, and Cell ID, plugging those numbers into a web app like Cell2GPS:

      This way will map the connected cell tower on Google Maps. Keep in mind the accuracy of the exact cell tower location can vary a bit depending on multiple variables.

      The example on Cell2GPS is a cell tower in the Bay Area of California ID’d as 310-260-328-29021, which is basically in the following format (MCC mobile country code) (MNC mobile network code) (Network) (LAC) (Cell ID)

      With some cellular providers (Verizon, etc) you can dial #878# and use the provided numbers as well.

  19. Michael says:

    While in Field Test Mode on an iPhone 6, how do I get back to the Field Test Menu to viewore details? Do I have to redial the code each time I want to view this menu?

    • Paul says:

      Once enabled, Field Test Mode will display the signals strength numbers in the status bar all the time on iPhone, but yes if you want to see the menus and the menu items you have to dial the number again.

  20. Najam says:

    In order to disable Field Test Mode, first enter the *3001#12345#* to bring up FTM then double press the home button to bring up app switching then quit the FTM app by dragging it upwards.

  21. Jim Kellner says:

    Much to my surprise, the persistent display of numbers instead of bars even survives version upgrades. Well done.
    (entered this mode under 8.1, now on 8.3, never had to re-do the process)

  22. Ed says:

    Did this go away with iOS 8.3?

    • cahono says:

      This exists in all versions of iOS, including iOS 8.3 and beyond. It is used by cell operators to troubleshoot networks. I am using it now in the newest version of iOS. Tap on the numbers or dots, or you may need to re-enable it.

  23. Brian says:

    Is there an equivalent for iPod Touches and wifi?

  24. Jason says:

    Nvm..I decided to turn it off and back on and everything some how got fixed

  25. Jason says:

    Bookmark** not homescreen

  26. Jason says:

    I did the field test mode and now I can’t save any home screens or anything on the reading list… What do I do?

  27. RejDrouin says:

    The number are dBm ; Decibel milliWatt. It is a power reading of the RF signal.

    0 dBm = 1,00 milliwatt (0,001 W)
    -3 dBm = 0,50 milliwatt
    -6 dBm = 0,25 milliwatt
    etc. (power cuts by half for every –3 dBm, or doubles for every 3 dBm increase.

    -118 dBm is considered to be the noise flour, the power measured when when there is not RF source of any kind.

  28. Jay says:

    iPhone 5 save feature didn’t work as described. Like Paul I went & powered down instead of trying to clear out by holding the home button. Power down & restart, that will save the feature.

  29. don says:

    4s users ios 7.0+ havig issues keeping #s you have to dbl click home and have mulitaskin open to get it to work

  30. paul says:

    Pressing home button after holding the power button to force quit FTM did not work for me. It kept bringing back the FTM. I just ended up entering feild test mode then holding power button till the slider appears and turned the phone off and back on and it worked for me that way.

  31. Daniel Rogers says:

    I’m following the steps exactly (I think)on my new 5s, but after the power off slide appears and I hold down the home button it merely goes back to FTM. When I exit FTM, it goes back to dots and stays there unless I dial into FTM again. I even tried holding the home button longer, but after 5 minutes it was still only in FTM. Suggestions?

  32. Anonymous says:

    This works on jailbroke iPhone for the WIFI strength, phone set to airplane mode, with SBSettings installed, and the option turned on to display these numbers inside SBSettings!!! Doing such, I can get the number to even reach -20 holding the phone Right Next to the WIFI Access Point. This will be very handy when diagnosing networks @ work. Thank You for explaining what the numbers mean!!! :) …Cheers!!!

  33. guy from poland says:

    Is it somehow possible to do the same on iPad? Specifically: iPad Mini Retina.

  34. kJohns says:

    Seems to be patched in 7.0.3 in the iPhone 5S.. FTM simply restarts.

    • whatwhy says:

      I am using field test now with iOS 7.0.4, it works fine though you may need to tap the bars again to re-enable it sometimes.

    • Anonymous says:

      I have the same problem with my iPhone 4S running iOS 7.0.4.

      • Pal says:

        Field Test Mode continues to work with all iPhone models running iOS 7.0.4, since it is used for testing it will probably always be possible to enable.

        Remember to tap on the little signal dots (rather than bars now) to switch between the Field Test Mode and the normal cellular strength signal.

  35. alaskan master says:

    -34 is the signal that you will see standing right in front of a UMTS sector (4G tower)

  36. SmashDanny says:

    Is there a way to disable this ?

    • Koen says:

      I assume you have force quit Field Test to show numbers instead of bars. To go back to bars you just need to re-open Field Test and everything will go back to normal.

      • SmashDanny says:

        No that didn’t worked. I tried it just with pressing the home button and with force quit. Also restarted my iPhone.

        • Wicho says:

          Just tap the Numbers and switch between Bars or Numbers. ;-)

          • SmashDanny says:

            It automatically switches from Bars to Numbers. For Example I open WhatsApp and the Bars change to Numbers. Then I tap on the Numbers change it to Bars, but maybe after 2 minutes it switches again.

  37. frank says:

    This is great for 3G but what about wifi? I’d like to be able to get the reading on my iPad/iPhone on how good my wifi signal is…

  38. evge says:

    I can’t seem to get rid of the bar at the bottom that showed up that covers the names at the bottom of my home screen. Any ideas besides whats been listed here.

  39. vdiv says:

    Aaaah, numbers… But what do they really mean?

  40. Ben says:

    This has been most useful to me over the last few weeks. Our reception is -45 a few hundred metres away, drops to -65 a hundred metres away then right down to -100 to -116 in or outside our house.
    Next to impossible to make a call for more than a couple of minutes. Telstra doesn’t care.

  41. Arthur says:

    Does it exist for android ? ^.^

  42. Andy Matheson says:

    Does this work in the UK?

  43. Mike Stead says:


    The bars are a QoS score not a signal strength score. In 3G networks it is possible to have very poor call quality with strong signal strength, and a perfectly good connection at very low signal strengths.

    3G is all about dominant-to-interfering carrier ratios. Suggesting this gives a more accurate idea of call quality is fundamentally incorrect.

  44. Richard says:

    Never mind. I missed the last * after the last #.

  45. Richard says:

    All I got was “Error performing request. Unknown error.” Tried it three times to be sure I dialed correctly.

  46. Jimmy says:

    Thanks for posting this. Is there a way to monitor 3G strength? Frequently, on Verizon, I have 3 or 4 bars of signal but 3G drops out completely.

    • Avenged110 says:

      Well technically this would track the strength of the signal being received by your phone which, assuming cell data is on, would consist of both CDMA and EVDO since they’re not really separate like Wi-Fi. Correct me if I’m wrong because I think I am.

  47. Avenged110 says:

    Just for fun, you can also keep the numerical value indicator even after exiting FTM. While in field test mode, hold the sleep/wake button until the shutdown slider comes up and then hold the Home button until the hidden app is force quit and you are returned to the Homescreen. The numerical value will remain in the status bar. To return to bars simply tap or re-enter FTM.

    Also FWIW I show -47 when using my M-Cell.

    • Grant says:

      Great tips here. What I think is amazing is how generous Apple is when reading the signals and interpreting that as full bars when for data transfer it can be a 1MB/s difference!

      And yes, the absolute maximum signal is -40 and that is basically if you are next to a cell tower or a microcell.

      • Zebediah says:

        -110 or up and you’ll start losing the call, -120 is not visible because there would be no reception.

        If you have an iPhone 4 you can bridge the antennas in the corner and force the phone into the -110 to -120 range, the whole “Antennagate” thing was real.

        • Avenged110 says:

          Ftr, I have an iPhone 4 on AT&T and I can only get it to drop about 1 bar when bridging the antennas. I don’t use a case and have never had any issues which surprised me, considering I’m left handed and always death grip it…

    • Anonymous says:

      Cool trick!

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