About Photography Calculators
Photography calculators give you the optical and exposure math behind every shot, the kind of numbers that used to live in a printed depth-of-field table tucked into the back of a Pentax light meter case. The collection covers the four calculations that come up over and over in the field: depth of field and hyperfocal distance, the exposure triangle (aperture, shutter speed, ISO), focal length and field of view across different sensor formats, and pixel density (PPI) for prints and screens. Every formula uses the standard photographic definitions: f-stops in 1/3 EV increments matching modern camera dials, the Zeiss circle of confusion convention (sensor diagonal / 1500), and the standard SI focal length and sensor measurements.
The depth of field calculator is the most-used. Enter sensor size (full-frame 36×24mm, APS-C ~24×16mm, Micro Four Thirds 17.3×13mm, or any custom), focal length, aperture, and subject distance, and it returns hyperfocal distance, near and far depth limits, and total DOF in front of and behind the focus point. The asymmetry (there's always more DOF behind the subject than in front, by a ratio that grows with subject distance) is the part that surprises new photographers and that landscape shooters rely on when they focus at the hyperfocal distance to maximize sharpness from half-hyperfocal to infinity. Circle of confusion uses the standard 0.030mm for full-frame (giving the canonical 1500-line resolution at 8×10" print viewed at arm's length), but the calculator lets you tighten it for critical work.
The exposure triangle calculator handles the inverse problem most photographers think about in their head: "I want to open up one stop for a shallower DOF, so what shutter speed gives me the same exposure?" It works in 1/3 stop increments matching the 1/3 EV detents on modern cameras, supports both EV and exposure-value tables, and flags reciprocity-failure regimes that affect long exposures on film. Focal length and field of view computes the angle of view (horizontal, vertical, and diagonal) for any focal length and sensor, plus the equivalent focal length on full frame, the number you need to compare a 50mm Micro Four Thirds lens (100mm equivalent FOV) against a 50mm on full frame.
The PPI calculator covers the print and display side: pixels per inch from resolution and screen diagonal, with quality ratings from "low" (under 100 PPI) through "Retina" (220+ PPI on a phone, 110+ on a tablet held at typical reading distance, 80+ on a 27" desktop monitor at arm's length). For prints, the standard rules of thumb are 240 PPI for inkjet, 300 PPI for offset and dye-sub, and 150 PPI as the realistic minimum for hung gallery prints viewed at 4-6 ft. The calculator outputs the maximum print size achievable at each quality threshold from any source resolution.
When to Use a Photography Calculator
- Calculating depth of field and hyperfocal distance for landscape, portrait, or product photography
- Solving the exposure triangle when changing one of aperture, shutter speed, or ISO
- Comparing focal lengths across full-frame, APS-C, and Micro Four Thirds sensors
- Calculating field of view for video framing or astrophotography composition
- Determining pixel density (PPI) for print sizing or screen resolution comparisons
- Sizing the maximum print resolution from a given file at standard 240 / 300 PPI thresholds
Frequently Asked Questions
What circle of confusion (CoC) value should I use?
The standard convention is sensor diagonal / 1500, giving roughly 0.030mm for full-frame, 0.020mm for APS-C, and 0.015mm for Micro Four Thirds. This corresponds to a sharp-looking 8×10 inch print viewed at arm's length. For critical work, large prints, or pixel-peeping at 100% on a 4K monitor, halve the CoC to roughly 0.015mm full-frame, so the resulting DOF will be tighter but more honest about what counts as truly sharp.
Why is depth of field always greater behind the subject than in front?
It's a consequence of the lens equation. The relationship between subject distance and image distance is non-linear, so the same circle of confusion at the image plane corresponds to a larger object-space distance behind the subject than in front. The asymmetry approaches infinity as you focus at the hyperfocal distance: the far DOF extends to infinity while the near DOF stops at half the hyperfocal distance.
What is hyperfocal distance and why does it matter?
Hyperfocal distance is the closest focus distance at which infinity is still acceptably sharp. Focus there and DOF extends from half the hyperfocal distance out to infinity, the maximum possible total DOF for that aperture and focal length. Landscape photographers use hyperfocal focusing to keep both a foreground rock and distant mountains sharp in a single frame.
How do I convert focal length between full-frame and crop sensors?
Multiply by the crop factor: 1.5× for most APS-C (Nikon, Sony, Fuji), 1.6× for Canon APS-C, 2.0× for Micro Four Thirds, 2.7× for 1-inch. A 50mm lens on Micro Four Thirds frames the same field of view as a 100mm lens on full frame. Aperture and DOF behavior also scale, so that 50mm f/2.8 on MFT has the DOF of a 100mm f/5.6 on full frame.
What PPI do I need for a high-quality print?
300 PPI is the gold standard for inkjet and offset printing, the resolution at which the human eye can no longer resolve individual pixels at typical reading distance. 240 PPI is acceptable for most fine-art inkjet work. For large prints viewed from several feet away (gallery walls, billboards), 150 PPI or even 100 PPI looks sharp because viewing distance scales with print size. Our PPI calculator gives the maximum print size at each threshold.