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PPI worksheet

Grades 8–9 · CCSS 8.G.B.7

Solve each problem and show your work. Round answers to 2 decimal places where needed.

  1. Problem 1.
    • Horizontal resolution: 1,800 px
    • Vertical resolution: 1,200 px
    • Diagonal screen size: 28 in

    Find: Pixel density

  2. Problem 2.
    • Horizontal resolution: 1,475 px
    • Vertical resolution: 900 px
    • Diagonal screen size: 16 in

    Find: Pixel density

  3. Problem 3.
    • Horizontal resolution: 2,100 px
    • Vertical resolution: 1,275 px
    • Diagonal screen size: 28 in

    Find: Pixel density

  4. Problem 4.
    • Horizontal resolution: 1,700 px
    • Vertical resolution: 800 px
    • Diagonal screen size: 20 in

    Find: Pixel density

  5. Problem 5.
    • Horizontal resolution: 2,000 px
    • Vertical resolution: 1,100 px
    • Diagonal screen size: 34 in

    Find: Pixel density

  6. Problem 6.
    • Horizontal resolution: 2,200 px
    • Vertical resolution: 1,300 px
    • Diagonal screen size: 26 in

    Find: Pixel density

  7. Problem 7.
    • Horizontal resolution: 2,300 px
    • Vertical resolution: 850 px
    • Diagonal screen size: 26 in

    Find: Pixel density

  8. Problem 8.
    • Horizontal resolution: 2,300 px
    • Vertical resolution: 1,075 px
    • Diagonal screen size: 24 in

    Find: Pixel density

  9. Problem 9.
    • Horizontal resolution: 1,300 px
    • Vertical resolution: 1,000 px
    • Diagonal screen size: 22 in

    Find: Pixel density

  10. Problem 10.
    • Horizontal resolution: 2,200 px
    • Vertical resolution: 1,000 px
    • Diagonal screen size: 22 in

    Find: Pixel density

Answer key: PPI worksheet

  1. 1. Pixel density: 77.26 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=1,8002+1,2002=2,163.330765 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,163.330765 px28 in=77.261813
    3. Divide each side's pixel count by the density to get its real length in inches

      1,80077.261813=23.297408 in,1,20077.261813=15.531605 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.477.261813=0.328752 mm
  2. 2. Pixel density: 107.99 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=1,4752+9002=1,727.89612 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=1,727.89612 px16 in=107.993507
    3. Divide each side's pixel count by the density to get its real length in inches

      1,475107.993507=13.658228 in,900107.993507=8.333834 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.4107.993507=0.235199 mm
  3. 3. Pixel density: 87.74 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,1002+1,2752=2,456.750903 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,456.750903 px28 in=87.741104
    3. Divide each side's pixel count by the density to get its real length in inches

      2,10087.741104=23.93405 in,1,27587.741104=14.531388 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.487.741104=0.289488 mm
  4. 4. Pixel density: 93.94 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=1,7002+8002=1,878.829423 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=1,878.829423 px20 in=93.941471
    3. Divide each side's pixel count by the density to get its real length in inches

      1,70093.941471=18.096374 in,80093.941471=8.515941 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.493.941471=0.270381 mm
  5. 5. Pixel density: 67.13 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,0002+1,1002=2,282.542442 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,282.542442 px34 in=67.133601
    3. Divide each side's pixel count by the density to get its real length in inches

      2,00067.133601=29.791341 in,1,10067.133601=16.385237 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.467.133601=0.37835 mm
  6. 6. Pixel density: 98.28 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,2002+1,3002=2,555.386468 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,555.386468 px26 in=98.284095
    3. Divide each side's pixel count by the density to get its real length in inches

      2,20098.284095=22.38409 in,1,30098.284095=13.226962 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.498.284095=0.258434 mm
  7. 7. Pixel density: 94.31 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,3002+8502=2,452.039967 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,452.039967 px26 in=94.30923
    3. Divide each side's pixel count by the density to get its real length in inches

      2,30094.30923=24.387857 in,85094.30923=9.012904 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.494.30923=0.269327 mm
  8. 8. Pixel density: 105.78 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,3002+1,0752=2,538.823546 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,538.823546 px24 in=105.784314
    3. Divide each side's pixel count by the density to get its real length in inches

      2,300105.784314=21.742354 in,1,075105.784314=10.162187 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.4105.784314=0.240111 mm
  9. 9. Pixel density: 74.55 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=1,3002+1,0002=1,640.121947 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=1,640.121947 px22 in=74.550998
    3. Divide each side's pixel count by the density to get its real length in inches

      1,30074.550998=17.437728 in,1,00074.550998=13.413637 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.474.550998=0.340706 mm
  10. 10. Pixel density: 109.85 PPI

    1. Find how many pixels fit along the diagonal, using the right-triangle rule (the Pythagorean theorem)

      d=2,2002+1,0002=2,416.609195 px
    2. Divide the pixels on the diagonal by the real diagonal in inches. That gives the pixels per inch

      PPI=2,416.609195 px22 in=109.845872
    3. Divide each side's pixel count by the density to get its real length in inches

      2,200109.845872=20.028063 in,1,000109.845872=9.103665 in
    4. Find the width of one pixel (the dot pitch): one inch, 25.4 mm, divided by the density

      25.4109.845872=0.231233 mm