DIY : How to Create a Tiled Slack Emoji During Your 10 Minute Paid Rest Period

What We’ll Be Making Today

I recently created a 7×3 Slack emoji (see Figure below) and I was really good at it so I wanted to share my tips and tricks for this cool party trick

A Subset of the Lyft Seattle Winter 2018 Interns (Photo Credit: me)

Number of Servings

The entire company

Cooking Time

As in, time to do this and/or play a game of Overcooked: 10 minutes


  • A landscape photo you would like to slice up for everyone to see and use across the Slack app
  • The Preview application (comes pre-installed on MacBooks)
  • A MacBook
  • Optional: a job in a state listed here (only if you would like to be paid during this activity otherwise, squeeze out 10 minutes of your own time)
  • This article printed out and taped over your secondary monitor
  • A calculator (or your computer or your brain)


  • The final tiled image will be made up of 21 pieces (7 columns x 3 rows). I found the limit by filling my message box with emojis and seeing at what point they would all shrink. Slack calls this feature jumbomoji, a setting turned on by default
Find out how many rows and columns of Drake will fit before they all shrink
  • Open up your image in Preview and use the Marquee tool to find your current dimensions. For this article, I will be demonstrating with a photo I’ve loved for as long as I can remember. When looking for the original owner through a quick Google Image Search, I was brought to one of the best sites I have ever seen (I am willing to overlook the stretching of images)
  • To me, selecting the portion of the image to use is the most difficult part. Here, you want to choose a rectangle with a length to width ratio of 7:3, hopefully capturing all the important details in the image. I’m choosing my image to be 588×252, which means each tile will be (588/7 = 252/3 = 84) 84×84. This is now your favorite number for the next 10 minutes
  • IMPORTANT: This number MUST be EVEN, my guess is that it has something to do with screen resolutions or the way Slack renders these images— you will get white lines separating each block if you choose to be odd
Photo Credit:
  • Crop the image with the button on the toolbar (or Command ⌘ + K). Now that we have a perfectly sized canvas, we are ready to turn up the heat
  • I like to work row by row, because this way we only have to worry about one dimension at a time. Select all (or Command ⌘ + A) and drag the centered bottom blue dot until you are left with a third of your image (84px height for me)
  • Hit crop again and we’ll start cutting up our first set of pieces. Select all and drag one side of your rectangle until you are left with your magical number. Just to give you an idea of what’s to come, we‘re going to go in one direction and slowly shuffle our way to the other side
Going piece by piece
  • Starting with the left most (or right most if you are left handed?) square, copy (Command ⌘ + C) and select File > New from Clipboard (or simply Command ⌘ + N). This will open up a new Preview window with your image from clipboard
  • Hit Save (Command ⌘ + S) and place your image in an easy to access location. The name of the file will be the name used on Slack, so think about what you want to use here
  • Notice I chose not to crop the image directly, because upon saving (which we could have done with a Save As (Command ⌘ + Shift + S) and undoing our change), our selection marquee will disappear and we would have to start all over again— inefficient!
  • Continue this process of moving across, copying, opening clipboard image, saving, until you complete the row and have seven completed images
There is already an emoji named dog2 so I had to scrap that idea
  • Hit undo until you get back to your perfectly cropped image (should be once if you followed along properly)
  • We will continue the procedure until we have completed all 21 tiles. How should we get the middle row perfectly?
33.33333333333333% done!
  • Once you’ve created all 21 pieces, there’s one more thing left to check. If your tiles are each larger than 128×128 pixels (aka if your magic number is greater than 128) or each image is greater than 64KB in size, you will need to follow the next few steps. Else, jump ahead to the next part (depicted by three centered dots) and get ready to upload to Slack!
  • OK, no worries if you are still here reading. We need to follow Slack’s guidelines or else you won’t be able to upload your “hard work”. I like to quit Preview (click on a Preview window and Command ⌘ + Q) so I can continue with a clean slate
  • Return to your folder containing your 21 children, select all and double click, prompting open Preview once again but this time, all in one window
  • We are here to add finishing touches to our images. Make sure all the images are selected in your Thumbnail View, and go to Tools > Adjust Size…
Yes, I have an insane amount of apps on display in my menu bar
  • Change your width and height each to 128px if they were larger. Make sure the Resulting Size is less than 64KB. If not, keep decreasing the dimensions to even numbers until you are within the range
  • Hit Save


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