Embedded display calculator
Frame buffer RAM, interface bandwidth and frame rate for any embedded display, checked against the chip you plan to use. Upload your UI design to see it on the screen at the panel’s real resolution.
See your screen at real size
Hold a bank card against your monitor once and match the outline. The mockup then shows the panel at its true physical size, and the 9 mm button is exactly 9 mm.
Hold any bank card or ID card flat against your screen, with its top left corner in the top left corner of the box. Move the slider until the outer edge of the black line lines up with the card edges on all sides.
Saved in this browser only. Calibrate again after changing browser zoom or moving to another monitor.
Your design stays in your browser. Nothing is uploaded to a server.
How much RAM a display needs
One frame is width × height × bytes per pixel. RGB565 uses 2 bytes per pixel, RGB888 uses 3. Double buffering needs two frames: the chip draws into one while the panel shows the other.
| Resolution | RGB565, one frame | RGB565, double | RGB888, one frame |
|---|---|---|---|
| 240 × 240 | 113 KB | 225 KB | 169 KB |
| 320 × 240 | 150 KB | 300 KB | 225 KB |
| 480 × 320 | 300 KB | 600 KB | 450 KB |
| 800 × 480 | 750 KB | 1.46 MB | 1.10 MB |
| 1024 × 600 | 1.17 MB | 2.34 MB | 1.76 MB |
| 1280 × 800 | 1.95 MB | 3.91 MB | 2.93 MB |
| 1920 × 720 | 2.64 MB | 5.27 MB | 3.96 MB |
| 1920 × 1080 | 3.96 MB | 7.91 MB | 5.93 MB |
Panels with their own memory (SPI, QSPI and 8080 parallel) can be redrawn in strips, so the chip only needs a partial buffer. LVGL works well with two buffers of 1/10 of the screen each. A 320 × 240 RGB565 screen then needs 30 KB instead of 150 KB.
SPI, RGB, MIPI DSI or LVDS
SPI and QSPI
Up to about 480 × 320. Full-screen frame rate is the clock divided by the bits in one frame: 320 × 240 RGB565 at 40 MHz gives 32.6 fps. QSPI sends 4 bits per clock.
8080 parallel
8 or 16 data lines with a write strobe. Each write moves one bus width, so RGB565 takes two writes on an 8-bit bus and one on a 16-bit bus.
RGB parallel
16 to 24 data lines driven continuously. The chip holds the full frame and streams it at the pixel clock: total width × total height × refresh rate, including blanking.
MIPI DSI
1 to 4 differential lanes. Each lane carries pixel clock × bits per pixel ÷ lanes. 1920 × 1080 at 60 Hz in RGB888 needs 891 Mbps per lane on 4 lanes.
LVDS
One channel carries up to about 80 MHz of pixel clock on common SoCs. Larger panels such as 1920 × 720 instrument clusters use two channels.
HDMI and DisplayPort
Used on Linux boards such as Raspberry Pi and Jetson. 1080p at 60 Hz needs 148.5 MHz, within every HDMI version.
Questions
Does a round display need less memory?
No. A round panel is driven as a square, so a 240 × 240 round display needs the same buffer as a 240 × 240 square one. About 79% of those pixels are visible.
Why is the real frame rate lower than the link limit?
The figure here is the time to send one full frame. Drawing the frame takes CPU or GPU time as well, and most UIs redraw only the areas that change, which is usually faster than a full frame.
What is blanking?
Extra clock cycles at the end of every line and frame used for sync. They add to the pixel clock, so 800 × 480 at 60 Hz needs about 27 to 33 MHz rather than 23 MHz.
What is the 9 mm box on the mockup?
The smallest button a finger can press reliably, about 9 mm square, drawn at its pixel size on the selected panel. It shows how much of the screen one button takes. Calibrate with a card and switch on Real size to see it at exactly 9 mm on your monitor.
Why does my design look pixelated?
The design is redrawn at the panel’s own resolution, then enlarged to fit your monitor. On small panels such as 240 × 240 you are seeing the real pixels, which is how the design will look on that hardware up close. Turn off Show real pixels for a smoothed view.
How does the card calibration work?
Bank cards and ID cards are all 85.6 × 54 mm. When the outline on screen matches a real card, the page knows how many screen pixels make one millimetre on your monitor, and draws the panel at its true size. The setting is kept in your browser only.
Is my uploaded design stored anywhere?
No. The image is read and drawn in your browser. It is never sent to a server.