Size

from	to	note
1cm	0.3937in
1in	2.54cm
1cm	28.346pt	72dpi
1cm	37.795px	96dpi
1rem	16px	default

• A4 为 A3 对折大小 - 可以此类推
• DPI - Dots Per Inch - 打印
  • 600 - 归档
  • 300 - 打印
  • 150
  • 72 - 普通
• PPI - Pixels Per Inch - 显示器

  • = 200 - 视网膜屏, HiDPI

• 银行卡/身份证
  • 8.56 cm × 5.398 cm
  • 85.6 mm × 53.98 mm
  • 3.37 inch × 2.125 inch × 0.0625
  • px - 1011 × 638
  • ISO/IEC 7810 - ID-1

Social	Size	Ratio
FB Page Cover	1640×664 px	1:2.46
FB Shared Image	1200×630 px	1:1.91
FB Event Image	1920×1080 px	16:9
FB Group Header	1640×856 px	1:1.91
Instagram	1080×1080 px	1:1
Insta Story	1080×1920 px	9:16
Youtube Profile	800×800 px	1:1
Youtube Cover	2560×1440 px	16:9
Twitter Profile	400×400 px	1:1
Twitter Header	1500×500 px	3:1

Print	Size	Pixel	pt
A3	297×420 mm
A4	210×297 mm	2480×3508	595.28, 841.89
A5	148×210 mm
B3	353×500 mm
B4	250×353 mm
B5	176×250 mm		498.9, 708.66
JIS B5	182x257 mm
Letter	8.5×11 in
Ledger	11×17 in
Business Card	3.5×2 in

• 1mm=2.83465pt
• 凭证封面
  • 252x148
  • 增票 243mm×142mm
  • A5 212x150
  • 240mm×140mm
  • 245mm×130mm
  • 245mm×150mm
  • 245mm×145mm
• Japanese Industrial Standards (JIS)
• https://github.com/diegomura/react-pdf/blob/master/packages/layout/src/page/getSize.js
• https://papersizes.io/japanese/jb5

Photo	inch	mm	note
Wallet	2×3 in
Enprint	3.5×5 in
-	8×12 in
-	12×18 in
-	16×24 in
-	20×30 in
-	24×36 in
2R	2.5×3.5 in
3R,L,5 寸	3.5×5 in
4R,KG,6 寸	4×6 in	102×152 mm
5R	5×7 in
6R	6×8 in
S8R,A4	8×10 in
10R	10×12 in
1 寸		25 x 35 mm
2 寸证件照		37  x  49 mm
标准 2 寸		37 x 53 mm

• 4R - 标准 135 底片尺寸
• R -> Rect
  • 2,4,6,8,10,12
• S -> Sequre
  • 4,6,8,10
• Cube - 2x3
• Wallet - 3x4
• 日本标准
  • E,L,KG,2L,8P,6P,6PW,4P,4PW
• Photo print sizes

Screen	Size
VGA	640×480 px
XGA	1024×768 px
HD	1280×720 px
-	1366×768 px
-	1440x900
-	1536×864 px
-	1600×900 px
Full HD	1920×1080 px
2K	2048×1080 px
UHD	3840×2160 px
4K	4096×2160 px

• https://gs.statcounter.com/screen-resolution-stats/desktop/worldwide

Mobile	Size
iPhone 4	640×900 px
iPhone 5	640×1136 px
iPhone 6 7 8	750×1334 px
iPhone 6+ 7+ 8+	1080×1920 px
iPhone X	1125×2436

AD	Size
Banner	468×60 px

Size	Screen
2880 x 1800	MBP 15
2560 x 1440	QHD/WQHD

system_profiler SPDisplaysDataType | grep Resolution

• https://screensizemap.com/

CSS Absolute length units

Unit	Name	Equivalent to	cn
cm	Centimeters	1cm = 96px/2.54	厘米
in	Inches	1in = 2.54cm = 96px	英寸
mm	Millimeters	1mm = 1/10th of 1cm	毫米
pc	Picas	1pc = 1/6th of 1in	派卡
pt	Points	1pt = 1/72th of 1in	点
px	Pixels	1px = 1/96th of 1in	像素
Q	Quarter-millimeters	1Q = 1/40th of 1cm	四分之一毫米

• https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Values_and_Units
  • Absolute length units

Resolution

Resolution	Ratio	Quality	low motion	high motion	audio
426x240	16:9	240p	400k	600k	64k
640x360	16:9	360p	700k	900k	96k
640x480	4:3	SD 480p	1000k	1200k	128k
854x480	16:9	480p	1250k	1600k	128k
1280x720	16:9	HD 720p	2500k	3200k	128k
1280x720	16:9	HD 720p 60fps	3500k	4400k	128k
1920x1080	16:9	FHD 1080p	4500k	5300k	192k
1920x1080	16:9	FHD 1080p 60fps	5800k	7400k	192k
3840x2160	16:9	4k	14000k	18200	192k
3840x2160	16:9	4k 60fps	23000k	29500k	192k

Res. Type	Name	Ratio	Size
SD	480p	4:3	640x480
HD	720p	16:9	1280x720
FHD	1080p	16:9	1920x1080
QHD	1440p	16:9	2560x1440
2K	1440p	16:9	2560x1440
4K UHD	2160p	16:9	3840x2160
8K FUHD	4320p	16:9	7680x4320

• 16:9 = 1.77
• SD - Standard Definition
• HD - High Definition
• FHD - Full High Definition
• UHD - Ultra High Definition
• QHD - Quad High Definition
• List of common display resolutions

Avatar

• github avatar 460x460
• Instagram
  • avatar 320x320
  • Square 1080x1080
  • Portrait 1080x1350
  • Landscape 1080x566
  • Stories & Reels 1080x1920