Calculate diagonal angle-of-view focal-length equivalence from actual focal length and exact source/reference image-area width and height.
A quick decision brief for this specific tool
Actual focal length plus exact active source and reference image-area width/height pairs
Source/reference diagonals, diagonal conversion factor, equivalent focal length, source angles of view and aspect ratios
Multiply actual focal length by reference diagonal divided by source diagonal, matching diagonal angle of view
Choose your path
Compare diagonal angle of view from exact source/reference image rectangles without hiding a default crop factor or extending equivalence to unrelated imaging properties.
Translate one actual focal length to an explicit reference rectangle.
Enter the active image dimensions for both formats rather than selecting a brand preset.
Gets a reproducible diagonal-equivalence value and conversion factor.
Account for the active capture area instead of the sensor’s nominal still-photo size.
Enter the mode-specific source width and height plus the chosen reference.
Avoids a silent generic crop factor.
Keep diagonal matching separate from horizontal/vertical framing.
Inspect source angles and both aspect ratios alongside the equivalent focal length.
Does not claim identical framing or perspective across different rectangles.
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
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Enter active picture width and height for the exact capture mode. The engine calculates both diagonals rather than silently preferring a generic crop factor or using width alone.
diagonal = √(width² + height²)Multiply actual focal length by reference diagonal divided by source diagonal. CIPA uses this diagonal relationship for 35 mm equivalent notation; this tool also permits another explicit reference rectangle.
f-equivalent = f-actual × diagonal-reference / diagonal-sourceEqual diagonal angle does not ensure equal horizontal and vertical angles when aspect ratios differ. The source horizontal/vertical angles and both aspect ratios remain visible for that reason.
AOV = 2 × atan(image dimension / (2f))Updated: August 2026
Enter the camera manual’s active image dimensions and the actual lens focal length. Retain the exact 36×24 mm default only if that is the intended reference, then report the diagonal-equivalent value with its source dimensions.
Use the mode-specific active width and height rather than the nominal full sensor. Cropping, electronic stabilization, open-gate capture, and post-production extraction can all change the comparison rectangle.
Inspect the matched diagonal angle together with source horizontal/vertical angles and both aspect ratios. Decide the intended crop or framing separately instead of claiming the views are identical.
This tool removes that conflicting-input path. Enter exact source/reference width and height, and let one diagonal ratio determine the result.
Label the result diagonal-angle-of-view equivalent and preserve the actual focal length, image rectangles, aspect ratios, viewpoint, aperture, and output conditions.
This calculator derives a diagonal conversion factor from two exact image rectangles. It compares diagonal angle of view only: actual focal length does not change, and perspective, exposure, depth of field, resolution, and horizontal or vertical framing are not automatically equivalent.