Image Resolution Calculator
Compute total pixels (megapixels) from image width and height, plus aspect ratio, print size at any DPI, and uncompressed file size. Enter any two of width, height, or megapixels and the third stays in sync.
Same MP, different shape
Megapixels alone does not describe an image — you also need the aspect ratio. A 12 MP image can be 4000×3000 (4:3, camera-native), 4243×2828 (3:2, DSLR), or 4618×2599 (16:9, cinema). The pixel count is identical; the shape is completely different. Cropping a 4:3 to 16:9 discards pixels and reduces the effective resolution, which is why cinematographers and photographers care about the aspect ratio of the sensor itself.
MP determines maximum print size
For photo-quality print, the target is 300 DPI. Print dimensions are pixel count divided by DPI: an 8×10 inch print needs 2400×3000 = 7.2 MP; a 16×20 needs 4800×6000 = 28.8 MP. This is why 12 MP is fine for 4×6 prints but not for wall-size poster prints, and why some archival photographers still shoot medium format (50–150 MP) despite modern phone cameras offering 48 MP or more — the sensor size and per-pixel quality matter more than the raw count.
Megapixels ≠ image quality
Two 48 MP images can look completely different. Sensor size, pixel pitch (the physical size of each photosite), lens quality, and noise all matter more than the raw pixel count. A full-frame 24 MP camera has better dynamic range, lower noise, and sharper real detail than a 1/2.3" sensor with 48 MP — because each photosite on the full-frame sensor is more than 10× the area. This is why "more MP" is often a marketing number, not a quality number.
Total pixels drive storage and bandwidth
Uncompressed size = W × H × bpp / 8 bytes. A 24 MP image at 24 bpp is about 72 MB uncompressed; the same image compressed as JPEG at quality 85 is typically 5–10 MB, and as HEIC about 3–6 MB. Video is even more dramatic: 4K at 24 bpp and 30 fps is ~750 MB/s uncompressed, which is why codecs like H.264 and H.265 exist — they use the pixel data's spatial and temporal redundancy to cut that by 100× or more.
How to Use This Calculator
Enter any two of width, height, or megapixels — the third stays in sync. DPI and bits per pixel are context fields that add print size and file size estimates.
1. Enter width, height, or MP
Type in any field or drag its slider. Editing W or H preserves the other dimension and recomputes MP. Editing MP preserves the current aspect ratio and recomputes both dimensions.
2. Use realistic presets
Widths cover 640 → 7,680 px; heights cover 480 → 4,320 px; MP presets cover 0.92 MP (720p) through 108 MP (flagship smartphone). Click any pill to snap to that value.
3. Read the result and verdict
The result card shows the featured value plus a size-class badge from "tiny thumbnail" through VGA, HD, FHD, QHD, 4K, 8K, pro camera, and medium format.
4. Set DPI for print size
Change the DPI field to see print dimensions at 72 (screen), 150 (draft), 300 (photo-quality), or 600 (fine art). Print size = pixels / DPI.
5. Set bits per pixel for file size
Change the bpp field to estimate uncompressed file size. 24 bpp = standard RGB, 32 bpp = RGBA, 48 bpp = 16-bit per channel.
6. Switch to Advanced for depth
Advanced mode adds a resolution-comparison bar chart, sensitivity analysis, and companion metrics including aspect ratio, diagonal pixels, pixel density at typical screen sizes, and print dimensions at common DPIs.
What This Tool Offers
Built around the fundamental resolution relation Total Pixels = Width × Height — the base calculation for every display, camera, and printer spec.
Three-way sync
Edit width, height, or megapixels — the other two update instantly. Editing MP preserves the current aspect ratio; editing W or H preserves the other dimension.
Aspect ratio detection
Computes the simplified aspect ratio (16:9, 4:3, 3:2, 21:9…) from the current width and height and shows it as a ratio and a decimal.
Print size at any DPI
Enter the DPI and see the maximum print dimensions in inches and centimetres at 72, 150, 300, and 600 DPI.
File size estimate
Compute the uncompressed file size at the current bits per pixel — useful for RAW workflows, buffers, and bandwidth planning.
Resolution charts
MP vs width for common aspect ratios, plus a bar chart of standard resolutions highlighting the current one.
Reference tables
A comprehensive lookup of standard display, camera, and print resolutions with pixel counts, MP, and aspect ratios.
Reference Tables & Conversions
An interactive converter, standard resolutions, common aspect ratios, and a full variable reference.
Width / height / MP converter
Common Display & Camera Resolutions
Standard resolutions across displays, cameras, and video formats, with pixel counts and aspect ratios.
| Name | Width × Height | Total pixels | MP | Aspect | Class |
|---|---|---|---|---|---|
| QVGA | 320 × 240 | 76,800 | 0.08 | 4:3 | Legacy mobile |
| VGA | 640 × 480 | 307,200 | 0.31 | 4:3 | Legacy / DOS |
| SVGA | 800 × 600 | 480,000 | 0.48 | 4:3 | Legacy desktop |
| XGA | 1024 × 768 | 786,432 | 0.79 | 4:3 | Legacy desktop |
| HD 720p | 1280 × 720 | 921,600 | 0.92 | 16:9 | HD video |
| HD+ 900p | 1600 × 900 | 1,440,000 | 1.44 | 16:9 | Laptop display |
| FHD 1080p | 1920 × 1080 | 2,073,600 | 2.07 | 16:9 | Full HD display |
| QHD 1440p | 2560 × 1440 | 3,686,400 | 3.69 | 16:9 | Quad HD display |
| 4K UHD | 3840 × 2160 | 8,294,400 | 8.29 | 16:9 | 4K display / video |
| 5K | 5120 × 2880 | 14,745,600 | 14.75 | 16:9 | 5K display |
| 8K UHD | 7680 × 4320 | 33,177,600 | 33.18 | 16:9 | 8K display / video |
| iPhone 15 Pro Max | 2796 × 1290 | 3,606,840 | 3.61 | 19.5:9 | Smartphone display |
| iPad Pro 12.9" | 2732 × 2048 | 5,595,136 | 5.59 | 4:3 | Tablet display |
| 12 MP camera | 4000 × 3000 | 12,000,000 | 12.00 | 4:3 | Phone / compact |
| 24 MP camera | 6000 × 4000 | 24,000,000 | 24.00 | 3:2 | DSLR / mirrorless |
| 48 MP camera | 8000 × 6000 | 48,000,000 | 48.00 | 4:3 | Modern smartphone |
| 108 MP camera | 12000 × 9000 | 108,000,000 | 108.00 | 4:3 | Flagship smartphone |
| Medium format 100 MP | 11648 × 8736 | 101,755,008 | 101.76 | 4:3 | Pro / high-end |
Common Aspect Ratios
The shape of the image, independent of resolution. Same MP count can be very different shapes.
| Aspect | Decimal | Example (at ~8 MP) | Typical use |
|---|---|---|---|
| 1:1 | 1.000 | 2828 × 2828 | Square / Instagram classic |
| 5:4 | 1.250 | 3200 × 2560 | Large-format print |
| 4:3 | 1.333 | 3264 × 2448 | Classic camera / iPad |
| 3:2 | 1.500 | 3464 × 2310 | DSLR / 35mm film |
| 16:10 | 1.600 | 3577 × 2236 | Laptops / MacBook |
| 16:9 | 1.778 | 3840 × 2160 | HD / 4K / cinema video |
| 21:9 | 2.333 | 4320 × 1851 | Ultra-wide monitors |
| 32:9 | 3.556 | 5120 × 1440 | Super ultra-wide |
Variable Reference
| Symbol | Meaning | Typical range | Formula |
|---|---|---|---|
| W | Width in pixels | 1 – 200,000 | input or MP / H |
| H | Height in pixels | 1 – 200,000 | input or MP / W |
| P | Total pixels | 1 – 10¹⁰ | W × H |
| MP | Megapixels | 0.01 – 500 | W × H / 10⁶ |
| AR | Aspect ratio | 0.1 – 10 | W / H |
| DPI | Print density | 36 – 1200 | input |
| bpp | Bits per pixel | 1 – 128 | input |
| size | Uncompressed file size | 0.001 – 10,000 MB | W × H × bpp / 8 / 10⁶ |
| Pwidth | Print width | 0.001 – 100 in | W / DPI |
What Does Total Pixels = Width × Height Measure?
The formula gives the total number of pixels in a raster image — the complete count of colour samples that make up the picture. It is the foundation for every specification that mentions resolution: camera sensors, display panels, printer output, video formats, and image file sizes all derive from this count. Megapixels (MP) is just total pixels divided by a million, a convenient unit because modern images range from under 1 MP to over 100 MP.
The Resolution Formula
The defining relationship is a simple product:
MP = (Width × Height) / 1,000,000
Given a target megapixel count and an aspect ratio, you can recover the dimensions:
Height = Width / AR
where AR = aspect ratio = W / H
And given pixel dimensions and a target print density, the maximum print size is:
Print height (in) = H / DPI
Image Resolution Variables
| Symbol | Meaning | Notes |
|---|---|---|
| W | Width | Horizontal pixel count |
| H | Height | Vertical pixel count |
| P | Total pixels | W × H — the fundamental count |
| MP | Megapixels | P / 10⁶ — convenient for modern images |
| AR | Aspect ratio | W / H, the shape of the image |
| DPI | Print density | Dots per inch, physical output resolution |
| bpp | Bits per pixel | Colour depth; 24 = RGB true colour |
Why Resolution Alone Doesn't Determine Quality
It is tempting to think that more megapixels means a better image. In practice, that is only weakly true. The actual quality of an image depends on the sensor's physical area, the size of each photosite, the quality of the lens, the sensor's noise floor, and the processing pipeline. A full-frame 24 MP sensor with large photosites captures a cleaner, more detailed image than a 1/2.3" 48 MP sensor whose photosites are 10× smaller and therefore collect far less light per pixel. The larger sensor also captures more total light, which is what actually determines noise and dynamic range.
Resolution does matter for one thing clearly: how large you can print or display without upscaling. A 12 MP image printed at 300 DPI produces an 8×10 inch print at native resolution. A 48 MP image can produce a 16×20 print at the same DPI. Beyond that size, you are either upscaling (interpolating) or accepting lower effective DPI. This is why large-format photographers still buy medium-format cameras (50–150 MP) instead of using a 48 MP phone: the phone's tiny sensor produces soft, noisy output that falls apart in a large print, while the medium-format sensor produces clean, detailed pixels that hold up at 40×60 inches and beyond.
Display is a different story. Almost no display today needs more than 8 MP: 4K is 8.29 MP, 8K is 33.18 MP. Phones with 108 MP sensors never actually store 108 MP of displayable detail — they use a process called "pixel binning" that combines groups of 4 or 9 photosites into one large virtual pixel, producing a 12 MP or 27 MP image with better low-light performance. The high native count is useful for computational photography tricks (multi-frame processing, digital zoom), not for viewing the full-resolution image directly.
For display screens, the metric that matters is pixel density, measured in pixels per inch (PPI). A 27" 4K monitor has ~163 PPI; a 27" 1080p monitor has ~82 PPI. The 4K panel renders text and graphics at almost 2× the detail, which is why it looks noticeably sharper. Beyond about 200 PPI, the human eye can no longer distinguish individual pixels at normal viewing distance, so higher densities give diminishing returns — this is why Retina displays stop around 220 PPI and 8K monitors at typical desktop sizes are of questionable value.
Resolution Calculation Examples
Total = 1920 × 1080 = 2,073,600 pixels
MP = 2,073,600 / 10⁶ = 2.07 MP
Total = 24 × 10⁶ = 24,000,000 pixels
W = √(24,000,000 × 1.5) = 6,000 px
H = 6,000 / 1.5 = 4,000 px
Print width = 3840 / 300 = 12.80 in
Print height = 2160 / 300 = 7.20 in
Size = 6000 × 4000 × 24 / 8 = 72,000,000 bytes
= 72 MB uncompressed
Frequently Asked Questions
It depends entirely on the sensor. A 24 MP full-frame camera easily outperforms a 12 MP compact camera — bigger sensor, larger photosites, better glass. But a 24 MP phone sensor with tiny photosites may actually produce noisier, softer images than a 12 MP sensor of the same size, because each photosite collects less light. The right question is not "how many MP" but "how large is the sensor, and how large are the photosites?" For the same sensor technology and area, more MP gives more detail but also more noise; the trade-off is a design decision, not a strict improvement.
At 300 DPI (photo-quality print standard), an 8×10 inch print requires 2400 × 3000 pixels = 7.2 MP. At 150 DPI (good for viewing from a distance), it needs only 1200 × 1500 = 1.8 MP. So an 8 MP or larger camera is more than enough for an 8×10 print at maximum quality. For a 16×20 print at 300 DPI you need 4800 × 6000 = 28.8 MP. For a 24×36 poster at 300 DPI you need 7200 × 10800 = 77.76 MP. This is why professional large-format printing often uses medium-format cameras or upscaling software.
Yes — cropping discards pixels and reduces the effective resolution proportionally. Cropping a 24 MP image from 3:2 down to a 4:5 portrait format throws away about 30% of the pixels, leaving roughly 17 MP. Cropping from 3:2 down to 16:9 (a common video-oriented crop) keeps about 84% of pixels, around 20 MP. This is why photographers using prime lenses for wildlife often prefer a higher-MP body: cropping heavily to "zoom" is possible without running out of resolution for the final use case.
Pixel density is the number of pixels per unit of physical length, typically measured in pixels per inch (PPI) for displays and dots per inch (DPI) for printers. A 27" 4K monitor has ~163 PPI; a 27" 1080p monitor has ~82 PPI; an iPhone 15 Pro Max has ~460 PPI. The relationship to resolution: for a fixed physical size, higher resolution means higher pixel density. Since the eye can only resolve up to roughly 200 PPI at normal viewing distance, higher densities give diminishing returns — this is why "Retina" displays stop around 220 PPI and 8K desktop monitors are of questionable value at typical sizes.
PPI (pixels per inch) is the resolution of a display or digital image — how many pixels fit in an inch of physical space. DPI (dots per inch) is the resolution of a printer — how many ink dots the printer lays down per inch. In the printing world, a single pixel is often rendered using multiple ink dots (especially with dithering), so 300 DPI on a printer is not the same as 300 PPI in an image. For practical purposes, they are often used interchangeably when specifying "print resolution", and industry convention is to prepare images at 300 PPI and print at 300 DPI for photo-quality output.
Uncompressed: size = W × H × bpp / 8 bytes. For a 6000×4000 image at 24 bpp, that is 6000 × 4000 × 24 / 8 = 72,000,000 bytes = 72 MB. Compressed JPEG at quality 85 is typically 5–10 MB, HEIC about 3–6 MB. Lossless PNG might be 20–40 MB for a photograph or 2–5 MB for a screenshot (which compresses much better). For video, multiply the per-frame size by the frame rate to get the uncompressed bitrate, then divide by the compression ratio (typically 100–400× for H.264/H.265). This calculator shows the uncompressed size at your current bpp setting.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| Total Pixels | Total pixel count | |
| Width | Image width | pixels |
| Height | Image height | pixels |
What it means
The total pixel count of a digital image is the product of its width and height in pixels. This represents the image resolution, often expressed in megapixels (millions of pixels). A 1920×1080 (Full HD) image has about 2.1 megapixels, while a 4K (3840×2160) image has about 8.3 megapixels. Higher pixel counts allow more detail but also require more storage and processing power. The total pixels determine the file size and the display area required. In photography, megapixel count is a key spec for cameras. In graphics, understanding pixel count is essential for scaling, cropping, and printing. The formula is also used in computer vision and machine learning, where input image dimensions define the feature space. It is a basic concept in imaging and multimedia. Keep in mind that pixel count does not capture color depth or compression, which also affect image quality.
Worked example
Image Resolution Pixels – Two Examples
Real‑World| Parameter | Value |
|---|---|
| Width | 3840 |
| Height | 2160 |
| Parameter | Value |
|---|---|
| Width | 6000 |
| Height | 4000 |
Common mistakes
- Width and height in pixels: Both are integer pixel counts.
- Megapixels: Divide the total by 1,000,000 for megapixels (not 1,024×1,024).
- Resolution vs. size: Total pixels determines the image size, but resolution also includes pixel density (DPI/PPI).
- Aspect ratio: Width and height may have a ratio; the product gives total pixels.
- Memory usage: Multiply total pixels by bytes per pixel (e.g., 3 for RGB) to get memory size.
Applications
Total pixel count in an image is simply width × height, giving the number of discrete picture elements that make up the image. This metric determines the image's resolution and directly affects file size, display quality, and processing requirements. Engineers use it to calculate storage and bandwidth needs, to design display and printing systems, and to scale images for different devices. In computer vision, pixel count influences algorithm complexity and accuracy. Understanding this formula is essential for choosing appropriate image sizes for web, mobile, and print applications, as well as for optimising performance in image‑processing pipelines.
- Image resolution specification and scaling
- Storage and bandwidth estimation for images
- Display and printing system design
- Computer vision and image processing
- UI/UX design for responsive images
Related calculators · Data Encoding & Conversion
Recently updated formulas
Suggest an improvement
Found a mistake? Have a better example? Let us know.
You may send up to 3 suggestions per 24 hours.