How Many Pixels in an Inch (PPI)?

There's no one right answer to this question

Illustration of a ruler on an iPad, measuring diagonally
Lifewire / Kelly Miller

The pixels per inch of a display is what's referred to as the pixel density or PPI. It's a measure of how many pixels you would count if you counted the pixels, horizontal or vertical, that exist in a single inch on your display.

There Is No One Answer to Pixels per Inch

If all pixels were the same size, the pixels in an inch would be a known number like how many centimeters in an inch (2.54) or how many inches in a foot (12).

However, pixels are different sizes on different displays, so the answer is 58.74 pixels per inch on a 75-inch 4K television, for example, but 440.58 pixels per inch on a 5"-inch full HD smartphone screen.

In other words, how many pixels per inch depends on the size and resolution of the screen you're talking about, so we'll have to do some math to get the number you're after for yours.

How to Calculate the Pixels in an Inch

Before we get into what looks like advanced math (it's not, don't worry), we've done the hard work for you for a number of displays in the Pixels Per Inch Table at the bottom of the page.

If you find your display's PPI, move on to How to Use Your Pixels per Inch Number, but if not, we'll figure it out right here with a few simple mathematical steps.

What you'll need in any case is the diagonal display size in inches as well as the resolution of the screen. Both of these numbers can be found on the technical specifications page of your display or device. See our page on how to find manufacturer tech support information if you need help digging this up.

Here's the full equation for you math savvy folks, but skip right past it for the step-by-step directions:

ppi = (√(w²+h²))/d

...where ppi is pixels per inch you're trying to find, w is the width resolution in pixels, h is the height resolution in pixels, and d is the diagonal size of the screen in inches.

If you slept during the order of operations chapter in math class, here's how you do this with an example of a 60" 4K (3840x2160) screen:

  1. Square the width pixels: 3840² = 14,745,600
  2. Square the height pixels: 2160² = 4,665,600
  3. Add those numbers together: 14,745,600 + 4,665,600 = 19,411,200
  4. Take the square root of that number: √(19,411,200) = 4,405.814
  5. Divide that number by the diagonal screen measurement: 4,405,814 / 60 = 73.43

In five short steps, we figured the pixels in an inch on a 60" 4K television to be 73.43 PPI. All you need to do now is repeat those five steps with your display, using your screen's resolution and size.

So now you know your display's PPI... but what good is it? If you were just curious, you're done! However, as we alluded to in the introduction above, most of the time a device or display PPI is the first of two steps to ​getting to something much more practical.

Determine How Big an Image Will Look on Another Device

Now that you know your screen or device PPI, it's time to put it to good use.

You may create or edit an image on your 17-inch laptop with an HD screen (129.584 PPI) but know that you'll be displaying it on an 84-inch 4K UHD display (52.45 PPI) in the office next week.

How can you be sure the image is being created large enough or has the right detail?

To answer this question, you'll first need to know the PPI of the device or display that you're curious about. We learned how to do that in the last section, or you found one or both numbers in the table below.

You'll also need to know the horizontal and vertical pixel dimensions of your image. You're creating or editing that so it should be easy enough to find in your graphics program.

Like before, here are the full equations if you're so inclined, but the instructions are below:

hsize = w/ppi
vsize = h/ppi

...where hsize and vsize are the image's horizontal and vertical sizes in inches, respectively, on the other display, w is the width of the image in pixels, h is the height of the image in pixels, and ppi is the PPI of the other display.

Here's how you do this if your image is 950x375 pixels in size and the display you're planning for is an 84-inch 4K (3840x2160) screen (52.45 PPI):

  1. Divide the width by the PPI: 950 / 52.45 = 18.11 inches
  2. Divide the height by the PPI: 375 / 52.45 = 7.15 inches

Here we showed that, no matter how "big" or "small" the image might appear to be on your screen, with pixel dimensions of 950x375, that image will appear to be 18.11" by 7.15" on that 84-inch 4K TV it'll be shown on.

Now you can use that knowledge as you see fit — maybe that's just what you were after, or maybe that's not big enough considering that an 84-inch screen is roughly 73 inches across and 41 inches tall!

Determine the Size an Image Will Print at Full Resolution

You don't need to figure your device or display PPI to figure out how big an image you print will be on paper.

All you need to know is information that's contained in the image itself - the horizontal pixel dimension, the vertical pixel dimension, and the image's PPI. All three pieces of data are available in the image's properties which you can find in your graphics editing program.

Here are the equations:

hsize = w/ppi
vsize = h/ppi

...where hsize and vsize are the image's horizontal and vertical sizes in inches, respectively, as they'll be printed, w is the width of the image in pixels, h is the height of the image in pixels, and ppi is the PPI of the image itself.

Here's how you do this if your image is 375x148 pixels in size and has a PPI of 72:

  1. Divide the width by the PPI: 375 / 72 = 5.21 inches
  2. Divide the height by the PPI: 148 / 72 = 2.06 inches

Assuming you don't scale the image during the printing process, the image will be physically printed at the size of 5.21 inches by 2.06 inches. Do the math with an image you have and then print it out — it works every time!

The DPI resolution your printer is set at, be it 300, 600, 1200, etc., does not impact the size that the image is printed at! This number is very similar to PPI and represents the "quality" by which the image sent to the printer is printed with but should not be included as part of your image size calculations.

Pixels Per Inch Tables

As promised above, here's our PPI "cheat sheet" which should save you the multi-step math we demonstrated above.

PPI Cheat Sheet
Size (in) 8K UHD (7680x4320) 4K UHD (3840x2160) Full HD (1920x1080)
145 60.770 30.385 15.192
110 80.106 40.053 20.026
85 103.666 51.833 25.917
84 104.900 52.450 26.225
80 110.145 55.073 27.536
75 117.488 58.744 29.372
70 125.880 62.940 31.470
65 135.564 67.782 33.891
64.5 136.614 68.307 34.154
60 146.860 73.430 36.715
58 151.925 75.962 37.981
56.2 156.791 78.395 39.198
55 160.211 80.106 40.053
50 176.233 88.116 44.058
46 191.557 95.779 47.889
43 204.922 102.461 51.230
42 209.801 104.900 52.450
40 220.291 110.145 55.073
39 225.939 112.970 56.485
37 238.152 119.076 59.538
32 275.363 137.682 68.841
31.5 279.734 139.867 69.934
30 293.721 146.860 73.430
27.8 316.965 158.483 79.241
27 326.357 163.178 81.589
24 367.151 183.576 91.788
23 383.114 191.557 95.779
21.5 409.843 204.922 102.461
17.3 509.343 254.671 127.336
15.4 572.184 286.092 143.046
13.3 662.528 331.264 165.632
11.6 759.623 379.812 189.906
10.6 831.286 415.643 207.821
9.6 917.878 458.939 229.469
5 1762.326 881.163 440.581
4.8 1835.756 917.878 458.939
4.7 1874.815 937.407 468.704
4.5 1958.140 979.070 489.535

Of course, not every device or display out there is exactly 8K UHD, 4K UHD, or Full HD (1080p). Here's another table with a number of popular devices with non-standard resolutions and their calculated PPI:

PPIs for Popular Devices
Device Size (in) Resolution (x/y) PPI
Chromebook 11 11.6 1366x768 135.094
Chromebook Pixel 12.9 2560x1700 238.220
Chromebox 30 30 2560x1600 100.629
Dell Venue 8 8.4 1600x2560 359.390
Dell Venue 11 Pro 10.8 1920x1080 203.972
Essential Phone 5.71 2560x1312 503.786
Google Pixel 5 1080x1920 440.581
Google Pixel XL 5.5 1440x2560 534.038
Google Pixel 2 5 1920x1080 440.581
Google Pixel 2 XL 6 2880x1440 536.656
Google Pixelbook 12.3 2400x1600 234.507
HTC One M8/M9 5 1080x1920 440.581
iMac 27 27 2560x1440 108.786
iMac 5K 27 5120x2880 217.571
iPad 9.7 768x1024 131.959
iPad Mini 7.9 768x1024 162.025
iPad Mini Retina 7.9 1536x2048 324.051
iPad Pro 12.9 2732x2048 264.682
iPad Retina 9.7 1536x2048 263.918
iPhone 3.5 320x480 164.825
iPhone 4 3.5 640x960 329.650
iPhone 5 4 640x1136 325.969
iPhone 6 4.7 750x1334 325.612
iPhone 6 Plus 5.5 1080x1920 400.529
iPhone 7/8 4.7 1334x750 325.612
iPhone 7/8 Plus 5.5 1920x1080 400.528
iPhone X 5.8 2436x1125 462.625
LG G2 5.2 1080x1920 423.636
LG G3 5.5 1440x2560 534.038
MacBook 12 12 2304x1440 226.416
MacBook Air 11 11.6 1366x768 135.094
MacBook Air 13 13.3 1440x900 127.678
MacBook Pro 13 13.3 2560x1600 226.983
MacBook Pro 15 15.4 2880x1800 220.535
Nexus 10 10.1 2560x1600 298.898
Nexus 6 6 1440x2560 489.535
Nexus 6P 5.7 1440x2560 515.300
Nexus 9 8.9 2048x1536 287.640
OnePlus 5T 6.01 1080x2160 401.822
Samsung Galaxy Note 4 5.7 1440x2560 515.300
Samsung Galaxy Note 8 6.3 2960x1440 522.489
Samsung Galaxy S5 5.1 1080x1920 431.943
Samsung Galaxy S6 5.1 1440x2560 575.923
Samsung Galaxy S7 5.1 2560x1440 575.923
Samsung Galaxy S8 5.8 2960x1440 567.532
Samsung Galaxy S8+ 6.2 2960x1440 530.917
Sony Xperia Z3 Tablet 8 1920x1200 283.019
Sony Xperia Z4 Tablet 10.1 2560x1600 298.898
Surface 10.6 1366x768 147.839
Surface 2 10.6 1920x1080 207.821
Surface 3 10.8 1920x1080 203.973
Surface Book 13.5 3000x2000 267.078
Surface Pro 10.6 1920x1080 207.821
Surface Pro 3 12 2160x1440 216.333
Surface Pro 4 12.4 2736x1824 265.182

Don't worry if you didn't find your resolution or device. Remember, you can calculate how many pixels are in an inch for your device, no matter the size or resolution, using the math we described above.