Crop Factor Calculator

A crop factor calculator shows how a camera sensor's size changes a lens's effective focal length and field of view compared to a full-frame (35 mm) sensor. Enter a sensor's width and height, or pick a common format, to get the crop factor, the full-frame equivalent focal length, and the horizontal and vertical field of view.

What Is Crop Factor?

Crop factor, also called the focal length multiplier, compares the diagonal measurement of a full-frame sensor to the diagonal of a smaller sensor. A full-frame sensor measures 36 mm by 24 mm. Its diagonal is about 43.27 mm. A sensor with a shorter diagonal has a crop factor greater than 1.

A higher crop factor means a smaller sensor. A camera with a 1.5× crop factor captures a narrower slice of a scene than a full-frame camera using the same lens. The image looks more zoomed in.

Crop Factor Formula

Crop factor is the full-frame sensor's diagonal divided by the sensor's own diagonal. Each diagonal comes from the Pythagorean theorem.

1Crop Factor = √(36² + 24²) / √(width² + height²)
2

Width and height are the sensor's dimensions in millimeters. The top part of the formula, √(36² + 24²), always equals about 43.27 mm, the full-frame diagonal.

Worked example

Take a Nikon or Sony APS-C sensor, 23.5 mm wide and 15.6 mm tall.

1. Sensor diagonal: √(23.5² + 15.6²) = √(552.25 + 243.36) = √795.61 ≈ 28.21 mm
2. Crop factor: 43.27 / 28.21 ≈ 1.53×

The calculator rounds this result to 1.53x.

How to Calculate Equivalent Focal Length

Equivalent focal length is the focal length a full-frame camera would need to match the field of view of a lens on a smaller sensor. The lens's real focal length does not change. The number only describes how the shot compares to a full-frame photo.

1Equivalent Focal Length = Actual Focal Length × Crop Factor
2

Example

A 50 mm lens on the APS-C sensor above gives:

50 × 1.5339 ≈ 76.7 mm equivalent focal length.

The calculator multiplies by the unrounded crop factor, 43.2666 / 28.2066 = 1.5339, so it shows 76.7 mm. Multiplying by the rounded 1.53 would give 76.5 mm instead.

The lens is still a 50 mm lens. It frames a scene the way a 76.7 mm lens would on a full-frame camera.

Field of View Formula

Field of view is the angle of the scene a lens captures. It depends on the focal length and on the sensor dimension being measured: width for horizontal field of view, height for vertical.

1Field of View = 2 × arctan(Sensor Dimension / (2 × Focal Length))
2

For the same 50 mm lens on the 23.5 mm × 15.6 mm sensor:

• Horizontal field of view: 2 × arctan(23.5 / 100) ≈ 26.4°
• Vertical field of view: 2 × arctan(15.6 / 100) ≈ 17.7°

Common Camera Sensor Sizes

The crop factors in this table are the rounded figures the industry publishes. The calculator works from the exact dimensions, so it shows 1.61× for Canon APS-C, 1.53× for Nikon/Sony APS-C, 2.00× for Micro Four Thirds, 2.73× for 1-inch, and 5.64× for 1/2.3-inch.

Canon's APS-C sensors and other brands' APS-C sensors are close in size but not identical. That is why their crop factors differ slightly: 1.6× for Canon, and about 1.5× for Nikon, Sony, and Fujifilm.

Smaller sensors have higher crop factors. The 1-inch and 1/2.3-inch formats, common in compact cameras and smartphones, sit well above 2×. Sensors larger than full frame have a crop factor below 1. A 44 × 33 mm digital medium-format sensor has a 55 mm diagonal, so its crop factor is 43.27 / 55 ≈ 0.79×. The calculator accepts those sizes and draws the larger sensor around the full-frame outline.

Full Frame vs. Crop Sensors

A smaller sensor is not automatically worse. Each size trades off differently.

Crop sensors let a photographer reach farther with a given lens. The smaller sensor uses only the center of the lens's image circle, an area many lenses render sharpest. Crop-sensor cameras and lenses also tend to be smaller, lighter, and cheaper than full-frame equivalents.

Full-frame sensors generally perform better in low light, because their larger pixels gather more light. They make it easier to get a shallow depth of field, the blurred-background look common in portraits. They also give a wider field of view for a given focal length, useful for landscape photography.

Crop factor does not change exposure. The same aperture, shutter speed, and ISO produce the same exposure on any sensor size.

Frequently Asked Questions

What does crop factor mean in photography? Crop factor is the ratio between a full-frame sensor's diagonal and a smaller sensor's diagonal. It shows how much a lens's field of view narrows on that smaller sensor compared to full frame.

Does a higher crop factor mean more zoom? No. The lens's actual focal length and optics stay the same. A higher crop factor only means the sensor records a smaller portion of the scene, which looks similar to using a longer lens on full frame.

Can a full-frame lens be used on a crop-sensor camera? Yes. The lens still projects a full image circle. The crop sensor simply captures the center portion of it.

Does crop factor affect image quality or exposure? No. Exposure depends on aperture, shutter speed, and ISO, not sensor size. Image quality depends more on sensor technology, pixel count, and lens quality than on crop factor.

Why do Canon and Nikon list different APS-C crop factors? Their APS-C sensors are slightly different sizes. Canon's measures 22.3 × 14.9 mm (1.6×). Nikon, Sony, and Fujifilm use about 23.5 × 15.6 mm (1.5×).

Is full frame always the better choice? Not for every situation. Crop sensors offer more reach per lens, smaller gear, and lower cost. Full frame offers a shallower depth of field and typically stronger low-light performance. The right choice depends on the kind of photography being done.