FB Display Memory Utility

Framebuffer Memory Calculator

Calculate framebuffer RAM from display width, height and pixel format. Include row-stride alignment, double or triple buffering and refresh rate to estimate total buffer memory, pixel throughput and raw framebuffer bandwidth.

✓ Resolution ✓ Bits Per Pixel ✓ Row Stride ✓ Double Buffer ✓ Triple Buffer ✓ Bandwidth

RAM

Framebuffer Size & Bandwidth

● Ready

Display Width (pixels) Number of active pixels in each framebuffer row.

Display Height (pixels) Number of active framebuffer rows.

Pixel Format / Bits Per Pixel Select the number of stored bits used for each pixel.

Framebuffer Count Multiple buffers multiply total framebuffer RAM.

Row Stride Alignment Each row is rounded upward to the selected byte alignment.

Refresh / Frame Rate (Hz) Used to estimate raw scan/framebuffer data rate.

Custom Row Stride (bytes, optional) If entered, overrides automatic stride calculation. It cannot be smaller than the minimum row size.

Available RAM (MiB, optional) Optional comparison against a RAM budget.

Core framebuffer formula: minimum row bytes = ceil(width × bits-per-pixel / 8). The row is then rounded to the selected stride alignment. buffer bytes = stride × height and total framebuffer RAM = buffer bytes × number of buffers.

Framebuffer Memory Result Calculated

Total Framebuffer RAM —

Resolution —

Total Pixels —

Color Depth —

Minimum Row Bytes —

Actual Row Stride —

Row Padding —

Single Buffer —

Buffer Count —

Total Buffer Memory —

Raw Pixel Bits —

Pixels / Second —

Raw Read Bandwidth —

Bandwidth in Mbit/s —

RAM Budget Used —

RAM Remaining —

Bytes Per Pixel —

Calculation Breakdown —

What Is a Framebuffer?

A framebuffer is a memory region that stores pixel data representing an image or display surface. A display controller, GPU or software renderer reads and writes this memory to generate the visible screen.

The amount of RAM required depends primarily on resolution, stored color depth, row stride and the number of framebuffers maintained simultaneously.

Framebuffer Memory Formula

For tightly packed pixels with no additional row alignment:

Framebuffer Bits =
Width × Height × Bits Per Pixel

Framebuffer Bytes =
ceil(Framebuffer Bits / 8)

For practical row-based storage, it is more accurate to calculate row size first because every row can require padding.

Framebuffer Row Size Formula

Minimum Row Bytes =

ceil(
    Width × Bits Per Pixel
    ----------------------
             8
)

The minimum row size is then rounded upward when the framebuffer requires a specific memory alignment.

800×480 RGB565 Framebuffer Example

Width:
800 pixels

Height:
480 pixels

RGB565:
16 bits/pixel
= 2 bytes/pixel

Row size:
800 × 2
= 1600 bytes

Single framebuffer:
1600 × 480
= 768,000 bytes

= 750 KiB
≈ 0.7324 MiB

Double Buffer Memory

Double buffering keeps two framebuffer surfaces. One can be displayed while software or hardware renders the next frame into the other buffer.

Single buffer:
768,000 bytes

Double buffering:
768,000 × 2

= 1,536,000 bytes

≈ 1.465 MiB

Triple Buffer Memory

Triple buffering maintains three full framebuffers. It can provide additional rendering flexibility but requires three times the memory of one framebuffer.

Total Memory =
Single Buffer Size × 3

Common Framebuffer Memory Sizes

Resolution	Format	Single Buffer
320 × 240	RGB565 / 16 bpp	153,600 bytes
800 × 480	RGB565 / 16 bpp	768,000 bytes
1280 × 720	RGB888 / 24 bpp	2,764,800 bytes
1920 × 1080	RGB888 / 24 bpp	6,220,800 bytes
1920 × 1080	ARGB8888 / 32 bpp	8,294,400 bytes

1920×1080 RGB888 Example

Pixels:
1920 × 1080
= 2,073,600 pixels

RGB888:
3 bytes/pixel

Framebuffer:
2,073,600 × 3

= 6,220,800 bytes

≈ 5.933 MiB

Double buffering that same RGB888 image requires approximately 11.87 MiB before additional alignment or graphics memory is considered.

1920×1080 ARGB8888 Example

1920 × 1080 × 4 bytes

= 8,294,400 bytes

≈ 7.910 MiB per buffer

Double buffering requires approximately 15.82 MiB and triple buffering approximately 23.73 MiB.

What Is Framebuffer Stride?

Stride, sometimes called pitch, is the number of bytes between the beginning of one framebuffer row and the beginning of the next row.

Stride can be larger than the visible pixel data because memory controllers, DMA engines, graphics accelerators or CPUs can require aligned row addresses.

Framebuffer Alignment Example

Suppose a row requires 1,503 bytes but the hardware requires 16-byte aligned rows.

Minimum row:
1503 bytes

Alignment:
16 bytes

Aligned stride:
ceil(1503 / 16) × 16

= 1504 bytes

That one extra byte is repeated for every framebuffer row.

Custom Framebuffer Stride

Operating systems and graphics APIs sometimes report a framebuffer pitch directly. When the actual pitch is known, use the Custom Row Stride field rather than recalculating it from width and color depth.

Buffer Size =
Reported Stride × Height

Bits Per Pixel vs Bytes Per Pixel

For byte-aligned formats, conversion is straightforward:

8 bpp  = 1 byte/pixel
16 bpp = 2 bytes/pixel
24 bpp = 3 bytes/pixel
32 bpp = 4 bytes/pixel

Sub-byte formats such as 1 bpp and 4 bpp pack multiple pixels into each byte. Formats such as packed 18 bpp can also cross byte boundaries.

RGB565 Framebuffer Memory

RGB565 requires 16 bits, or two bytes, for each pixel. It is popular in embedded systems because it uses substantially less memory than RGB888 while supporting 65,536 colors.

Framebuffer Bytes =
Width × Height × 2

when rows need no extra padding.

Monochrome Framebuffer Memory

A one-bit framebuffer requires only one bit for each pixel. A 128×64 monochrome display has 8,192 pixels.

128 × 64
= 8192 bits

8192 / 8
= 1024 bytes

The physical display controller may organize those bytes into pages or other layouts, but the raw one-bit storage requirement remains approximately 1 KiB.

Framebuffer Bandwidth

If an entire framebuffer is read for every refresh, a simple raw bandwidth estimate is:

Bandwidth =
Framebuffer Bytes
×
Refresh Rate

This represents one full-frame read per refresh. Real systems can require more bandwidth because rendering also writes memory, layers can be blended, caches can miss and display engines can read multiple surfaces.

800×480 RGB565 at 60 Hz Bandwidth

Single framebuffer:
768,000 bytes

Refresh:
60 Hz

Read bandwidth:
768,000 × 60

= 46,080,000 bytes/s

≈ 43.95 MiB/s

Pixel Throughput

Pixel throughput is the number of active pixels processed each second:

Pixels Per Second =
Width × Height × Refresh Rate

For 800×480 at 60 Hz:

800 × 480 × 60
= 23,040,000 pixels/s

Framebuffer RAM vs Display Interface Bandwidth

Framebuffer memory bandwidth and physical display-interface bandwidth are related but not identical. Interfaces such as RGB parallel, MIPI DSI, HDMI, LVDS and SPI can include blanking periods, encoding overhead or protocol headers.

The bandwidth result on this page represents raw active framebuffer data and should not be treated as the complete wire-rate requirement for every display interface.

Why Double Buffering Uses More RAM

A second framebuffer allows the next frame to be rendered separately from the one currently being displayed. The buffers can then be swapped, which helps prevent visible tearing.

The tradeoff is memory: double buffering needs approximately twice the framebuffer storage, while triple buffering requires approximately three times the storage.

Framebuffer Memory Calculator FAQs

How do I calculate framebuffer memory?

Calculate the number of bytes required for one row from width and bits per pixel, apply any row alignment, then multiply the stride by display height and buffer count.

How much memory does an 800×480 RGB565 framebuffer need?

With tightly packed 16-bit pixels, one framebuffer requires 768,000 bytes, which is 750 KiB or about 0.732 MiB.

How much memory does 1920×1080 RGB888 need?

One tightly packed 24-bit framebuffer requires 6,220,800 bytes, or about 5.93 MiB.

How much memory does 1080p ARGB8888 need?

A 1920×1080 framebuffer at 32 bits per pixel requires 8,294,400 bytes, or about 7.91 MiB.

What is framebuffer stride?

Stride is the byte distance from the start of one framebuffer row to the start of the next row. It can include padding beyond the visible pixel data.

Does double buffering require twice the memory?

Yes, if both buffers have the same dimensions, pixel format and stride.

Does triple buffering require three times the memory?

Yes, for three equally sized full-screen buffers.

Why can actual framebuffer memory exceed width × height × bytes per pixel?

Row alignment, pitch requirements, tiled layouts or other hardware-specific storage rules can increase the allocated size.

Does the bandwidth result include framebuffer writes?

No. It estimates one raw framebuffer read for every refresh. Rendering, blending and other memory traffic can significantly increase total bandwidth.

Can I enter a known framebuffer pitch?

Yes. Enter the actual pitch in Custom Row Stride and it will override the automatic alignment calculation.

Calculate Framebuffer RAM and Bandwidth

Estimate graphics-memory requirements for embedded displays, Linux framebuffers, LCD controllers and software-rendered surfaces using resolution, pixel depth, stride alignment and buffer count.