Photo & Video
Photo & Video tools on UniTools: aspect ratio, dpi and print size and more.
This section covers the numbers behind shooting and preparing material: aspect ratios and proportional resizing, pixels converted into printed centimetres, video file size from bitrate, and how much a memory card actually holds.
The rest is optics: depth of field and hyperfocal distance corrected for sensor size, crop factor with equivalent focal length and aperture, exposure in stops, plus screen pixel density and the golden ratio for layout work.
Tools in this category
Aspect Ratio Calculator
Reduces a pixel size to its aspect ratio, finds the nearest standard proportion, and works out the second side when the ratio is fixed in advance.
DPI and Print Size Calculator
Turns pixels into printed centimetres at a given resolution, and answers the reverse question of how many pixels a given format needs.
Image Resize Calculator
Works out the second dimension when the first changes, gives the scale as a percentage, and estimates what happens to the file size.
Video File Size Calculator
Works out video file size from bitrate and running time, and the reverse — the bitrate needed to fit a given file size.
Depth of Field Calculator
Works out the near and far limits of sharpness and the hyperfocal distance from focal length, aperture, subject distance and sensor size.
Crop Factor Calculator
Converts focal length and aperture into full-frame equivalents for APS-C, Micro Four Thirds and other sensor sizes.
Exposure Calculator
Works out the shutter speed that preserves exposure at a different aperture or ISO, and expresses the changes in stops.
Golden Ratio Calculator
Splits a size by the golden ratio, extends a given value into a golden pair, and gives the sides of a golden rectangle.
Screen PPI Calculator
Works out pixel density from resolution and diagonal, the physical size of a pixel, and the distance at which individual pixels stop resolving.
Memory Card Capacity Calculator
Works out how many photographs and minutes of video fit on a memory card at your chosen format and bitrate.
Related categories
FAQs
How do I find an image's aspect ratio?+
Divide width and height by their greatest common divisor. For 1920 and 1080 that is 120, which gives 16:9.
How many pixels for an A4 print?+
At 300 DPI, 2480 × 3508 pixels — about 8.7 megapixels. At 150 DPI a quarter of that is enough.
What sets depth of field?+
Subject distance above all, then focal length, aperture and sensor size.
Does crop factor change the light gathered?+
For exposure, no: f/1.8 stays f/1.8. For depth of field and total light on the sensor, yes — multiply the aperture by the crop factor.