I want to scan slides and present them in a slideshow on a TV. The TV is 40 inches with a resolution of 1920 × 1080 pixels. What should be the scan resolution?

A slide measures 1.417 × 0.945 in. The aspect ratio does not match the TV's 16:9 (3:2 vs 16:9), so we only calculate the pixel density for the height: dpi = 1080 / 0.945 ≈ 1143 dpi. Consequently, the image width is: px = 1143 × 1.417 ≈ 1620 px.

Pixel Calculator

Q: How do I calculate the print size in inches?

Basic formula: Length[in] = pixels / dpi. Example: Length[in] = 3273 / 300 = 10.91 in.

Q: How do I calculate the pixels?

Basic formula: Pixels = dpi × Length[in]. Example: Pixels = 300 × 10.91 = 3273 px.

Q: How do I calculate the dpi?

Basic formula: dpi = pixels / Length[in]. Example: dpi = 3273 / 10.91 = 300 dpi.

Q: How do I calculate the file size?

Basic formula: Size[MB] = (Width × Height × 24) / (8 × 1M). Example: Size[MB] = (3273 × 2445 × 24) / (8 × 1M) = 24 MB.

Q: I have an image with 3264 × 2448 pixels and want to print it as a poster. How large can the poster be printed?

For a poster, a pixel density of around 100 dpi is often sufficient. Example: Length[in] = 3264 / 100 = 32.64 in, Width[in] = 2448 / 100 = 24.48 in.

Q: I want to print a slide as a poster with maximum resolution at a size of 35.43 × 23.62 inches. What will be the dpi quality?

The scanner's maximum resolution is 4000 dpi and the slide measures 1.417 × 0.945 in. First, calculate the pixel count: Pixel = 4000 × 1.417 ≈ 5668 px. Then, dpi for the poster: dpi = 5668 / 35.43 ≈ 160 dpi.

The Pixel Calculator – the precise tool for image editing, photography, and printing. Quickly and accurately calculate the relationship between image resolution (pixels, Mpx), print size (mm, cm, inches) and pixel density (dpi, ppi). Perfect for photographers, designers, and anyone working with digital images.

Formulas Examples Units Printing Standards

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Ratio

Given ratio:

mm ⇒ Pixel

dpi

= × Pixel

Pixel ⇒ mm

dpi

= × mm

Pixels & mm ⇒ dpi

= dpi

Total Pixels	× = Mpx
Image Size	× mm
DPI / PPI
Aspect Ratio	x:y
Color Depth
File Size (TIF)
File Size JPG (80%)
Pitch	μm
Pixel Size	μm²

Preview aspect ratio

Open Full Preview Ratio x:y

sponsored by: Dia Foto Film Scannen www.archivscan.ch

Formulas

Key terms explained briefly:
DPI refers to print dot density (Dots per Inch)
PPI refers to digital resolution in pixels per inch
Understanding the difference is essential for proper image preparation.

Calculation of length or width, pixels and DPI with the following parameters:

Image

3273×2445 Pixel (8Mpx, 4:3)

Print Size

10.91 × 8.15 in

Pixel Density

300dpi

File Size

TIF Color RGB in MB

Basic formula: How do I calculate the print size in inches

Length[in] = pxdpi

Example: Image width 3273 px at 300 dpi

Length[in] = 3273300 = 10.91 in

Basic formula: How do I calculate the pixels

Pixel = dpi × Length[in]

Example (approximation)

Pixel = 300 × 10.91 = 3273 px

Basic formula: How do I calculate the dpi

dpi = PixelLength[in]

Example

dpi = 327310.91 = 300 dpi

Basic formula: How do I calculate the file size

Size[MB] = Width × Height × 248 × 1M

Example

Size[MB] = 3273 × 2445 × 248 × 1M = 24MB

Examples

I want to print a photo in 5 × 7 inch format at high quality. What resolution in pixels is required?

A high-quality photo is printed at 300 dpi. To calculate the resolution in megapixels, multiply the number of pixels in width and height and then divide by one million.

Pixel X = 300 × 5 = 1500 px

Pixel Y = 300 × 7 = 2100 px

Resolution = 1500 × 21001000000 = 3.15 Mpx

I have an image with 3264 × 2448 pixels and want to print it as a poster. How large can the poster be printed?

Unlike a small photo album image, a poster does not require high pixel density since it is viewed from a distance. Approximately 100 dpi is recommended for posters.

Length[in] = 3264100 = 32.64 in

Width[in] = 2448100 = 24.48 in

I want to scan slides and present them in a slideshow on a TV. TV screen 40 inches; Resolution: 1920 × 1080 pixels. What should be the scan resolution?

A slide measures 1.417 × 0.945 inches. The aspect ratio does not match that of the TV (16:9 vs. 3:2), so we only calculate the pixel density for the height.

dpi = 1080 × 10.945 = 1143 dpi

Resulting image width in the correct aspect ratio:

px = 1143 × 1.417 = 1620 px

I want to print a slide as a poster with maximum resolution at a size of 35.43 × 23.62 inches. What will be the quality in dpi?

The scanner's maximum resolution is 4000 dpi. A slide measures 1.417 × 0.945 inches. After calculating the number of pixels, the pixel density for the poster can be determined.

Pixel = 4000 × 1.417 = 5668 px

dpi = 566835.43 = 160 dpi

Units of Measurement

English Unit	1 inch = 25.4 mm
Dots per Inch (dpi)	1 dpi = 1 dot per inch = 1 dot per 25.4 mm
Pixels per Inch (ppi)	1 ppi = 1 pixel per inch = 1 pixel per 25.4 mm
Digital Units	1 bit = 0 or 1 1 Byte (B) = 8 bit 1 kB = 1024 B 1 MB = 1024 kB

Standard Print Resolutions for Consumer Photo Services

Many international photo services and labs use professional digital printing systems such as the Fujifilm Frontier series, Noritsu Drylabs or Canon PRO/Maxify systems. These are used worldwide in photo printing – both in the consumer sector and in professional segments. They are usually printed on high-quality photo paper such as Fujicolor Crystal Archive or similar materials.

Print resolution – measured in DPI (dots per inch) – is crucial for image quality. The smaller the format or the shorter the viewing distance, the higher the DPI value should be. For large-format prints, a lower DPI value is acceptable since they are viewed from a greater distance.

Well-known International Photo Services

The following providers are leading worldwide or in Europe in the field of online photo printing and adhere to the standards mentioned above:

CEWE – One of the world's largest photo services, active in over 20 countries (often under local brands such as dm-Fotoparadies, Müller, Saturn, etc.)
Shutterfly – Market leader in the USA, offering a comprehensive range of photo and gift products
Snapfish – Internationally active (USA, UK, Australia), known for fast consumer printing
Photobox – A large platform focused on the UK, France, and Europe
Pixum – Leading online photo service in the German-speaking region (Germany / Europe)
ifolor – A Swiss quality provider with market presence throughout the EU
WhiteWall – Specialist in gallery and fine art prints, with international shipping
Mpix – A high-quality provider in the USA, popular among professional and portrait photographers

Many of these providers automatically check the resolution of your image file during upload and provide guidance on whether the chosen print format is suitable. The values in the table below correspond to the requirements of these platforms.

Common Resolutions by Format Size

300 DPI for photo prints, postcards, and small posters
200–250 DPI for medium poster formats up to approximately 20×30 inches
150 DPI for large posters and wall art (e.g., 32×47 inches)
72–100 DPI for XXL formats such as advertising banners or posters

Print Formats with Recommended Resolution

Format (W × H in, exact)	Common Name	Recommended DPI	Typical Use	Pixels (W × H)
2 × 3 in	Wallet Size	300	Passport, Wallet photos	600 × 900
4 × 6 in	Standard Print (4R)	300	Photo prints	1200 × 1800
5 × 7 in	5R	300	Photo prints, Framed photos	1500 × 2100
8 × 10 in	Classic Enlargement	300	Framed portraits	2400 × 3000
8.5 × 11 in	US Letter	300	Photo documents, portfolios	2550 × 3300
11 × 14 in	Large Print	250	Wall display	2750 × 3500
16 × 20 in	Poster	200	Posters, wall art	3200 × 4000
18 × 24 in	Medium Poster	200	Displays, graphics	3600 × 4800
20 × 30 in	Large Poster	150	Event posters	3000 × 4500
24 × 36 in	Movie Poster	150	Promotional display	3600 × 5400
36 × 48 in	Exhibition Print	100	Posters, Banners	3600 × 4800
> 36 × 48 in	Billboard / Large Format	72–100	Billboards, large displays	varies