Crop Factor Calculator
Enter your camera sensor size and lens specs to get the crop factor, 35mm equivalent focal length, and equivalent aperture in seconds. Pick a preset sensor or enter custom dimensions. The reverse mode lets you work backwards: enter the 35mm equivalent focal length you want and find the actual focal length you need for your crop sensor. Results update as you type.
Formula
Worked example
A Nikon APS-C sensor (23.5 x 15.6 mm) has a diagonal of sqrt(23.5^2 + 15.6^2) = 28.2 mm. Crop factor = 43.27 / 28.2 = 1.53x. A 35mm f/1.8 lens becomes equivalent to a 53.6mm f/2.8 lens on a full-frame camera.
What is crop factor?
Crop factor (also called focal length multiplier) is the ratio between the diagonal of a 35mm full-frame sensor and the diagonal of a smaller camera sensor. A full-frame sensor measures 36 x 24 mm, giving a diagonal of about 43.27 mm. Any sensor smaller than that has a crop factor greater than 1.0. The name comes from the fact that a smaller sensor captures a narrower, cropped slice of the image projected by the lens, as if you had cropped a full-frame photo. A Canon APS-C sensor (22.3 x 14.9 mm) has a crop factor of about 1.6x. A Micro Four Thirds sensor (17.3 x 13 mm) has a crop factor of about 2.0x. Medium-format sensors are larger than full-frame, so they have a crop factor below 1.0 (around 0.64x for a 53.4 x 40 mm sensor).
How crop factor affects focal length and field of view
A lens projects the same image circle regardless of which camera body it is mounted to. A smaller sensor only uses the central part of that circle, so the resulting image shows a narrower field of view, as if you had zoomed in. To get the apparent field of view, multiply the actual focal length by the crop factor. A 50mm lens on an APS-C camera (1.5x) frames the scene like a 75mm lens on a full-frame body. This narrowing of the field of view is often called the reach advantage: wildlife and sports photographers with a 300mm lens on a 1.5x body get the framing of a 450mm full-frame lens at a fraction of the cost and weight. For landscape and architectural photographers, however, it means you need shorter actual focal lengths to achieve wide-angle coverage.
How crop factor affects aperture and depth of field
This is the part that surprises many photographers. Crop factor affects depth of field and the bokeh rendition of lenses, not just field of view. A 50mm f/1.8 lens on a 2.0x Micro Four Thirds camera gives the same field of view as a 100mm lens on full-frame, but the depth of field matches a 100mm f/3.6 lens, not f/1.8. To compare depth of field between formats, multiply the aperture by the crop factor. Note that the actual light gathering (the physical amount of light reaching the sensor per unit area) is not changed by the crop factor. A lens set to f/1.8 is still f/1.8 for exposure purposes. The aperture multiplication only applies when comparing depth of field and bokeh across formats.
Reverse mode: planning a purchase or a shot
Use the reverse mode when you know the look you want and need to figure out which lens to buy or borrow. Enter the 35mm equivalent focal length and aperture that give you the field of view and depth of field you are after, and the calculator tells you the actual focal length and f-stop to look for in a lens designed for your crop-sensor camera. For example, if you want the classic 85mm f/1.4 portrait look on a Micro Four Thirds body (2.0x), you need a 42.5mm f/0.7 lens. Several manufacturers make 42.5mm f/1.7 lenses for MFT, which approximate the field of view but not the shallow depth of field. Knowing both numbers helps you make a fully informed decision.
Common camera sensor formats and crop factors
| Format | Sensor Size (mm) | Crop Factor | Example Cameras |
|---|---|---|---|
| Medium Format | 53.4 x 40 | 0.64x | Fujifilm GFX 100S, Hasselblad X2D |
| Full Frame | 36 x 24 | 1.0x | Sony A7 IV, Canon R6, Nikon Z6 III |
| APS-H | 28.7 x 19.1 | 1.29x | Canon 1D series (older models) |
| APS-C (Nikon/Sony/Fuji) | 23.5 x 15.6 | 1.5x | Nikon Z50, Sony A6700, Fujifilm X-T5 |
| APS-C (Canon) | 22.3 x 14.9 | 1.6x | Canon R50, Canon R10 |
| Micro Four Thirds | 17.3 x 13 | 2.0x | OM System OM-5, Panasonic G9 II |
| 1-inch | 13.2 x 8.8 | 2.7x | Sony RX100 VII, Nikon Z30 |
| 2/3-inch | 8.8 x 6.6 | 3.9x | Older Fujifilm bridge cameras |
| 1/1.7-inch | 6.17 x 4.55 | 5.6x | Higher-end compact cameras |
| 1/2.3-inch | 6.17 x 4.56 | 5.6x | Most consumer action cameras |
| 1/2.5-inch | 5.76 x 4.29 | 5.9x | Smartphone cameras (typical) |
Crop factor is calculated as the ratio of the 35mm full-frame sensor diagonal (43.27 mm) to the sensor diagonal of the format.
Frequently asked questions
Does crop factor affect image quality?
Not directly, but sensor physical size does. Smaller sensors pack the same or more pixels into a smaller area, which can increase noise at high ISO settings because each photosite captures less light. Crop factor itself is just a geometric ratio that describes field of view and depth of field equivalence. Many modern APS-C and Micro Four Thirds cameras produce excellent images.
Is a higher or lower crop factor better?
Neither is universally better. A lower crop factor (larger sensor) gives a wider field of view per focal length, shallower depth of field for a given equivalent field of view, and generally better high-ISO performance. A higher crop factor (smaller sensor) gives more reach from the same lens, smaller camera bodies, and often lower cost. The best crop factor depends on your subject matter.
Can I use a full-frame lens on a crop-sensor camera?
Usually yes, with the right mount adapter or if the system is compatible. The full-frame lens projects an image circle large enough to cover the smaller sensor, so vignetting is rarely a problem. You just apply the crop factor to find the equivalent focal length. The reverse is not always true: a lens designed for a small sensor (APS-C, for example) may not cover the full-frame image circle and will vignette badly if used on a full-frame body.
How is crop factor calculated?
Crop factor is the ratio of the 35mm full-frame sensor diagonal to the diagonal of your sensor. The full-frame diagonal is sqrt(36^2 + 24^2), which equals about 43.27 mm. If your sensor measures 23.5 x 15.6 mm, its diagonal is sqrt(23.5^2 + 15.6^2), or about 28.22 mm. Dividing 43.27 by 28.22 gives a crop factor of about 1.53.
What is the crop factor for APS-C cameras?
APS-C is not a perfectly standardised size, so crop factor varies slightly by manufacturer. Nikon, Sony, and Fujifilm APS-C sensors (approximately 23.5 x 15.6 mm) have a crop factor of about 1.5x. Canon APS-C sensors (22.3 x 14.9 mm) are slightly smaller, giving a crop factor of about 1.6x.
Does crop factor apply when shooting video?
Yes, and video crop can differ from the still-image crop on the same camera. Many cameras read out a smaller area of the sensor for 4K or high-frame-rate video, adding an additional crop on top of the sensor crop factor. Check your camera manual for the exact video crop factor at each resolution and frame rate setting.
What is a teleconverter and how does it interact with crop factor?
A teleconverter is an optical accessory that multiplies a lens focal length by a fixed factor (commonly 1.4x or 2.0x). The effective focal length is the lens focal length multiplied by the teleconverter factor. To find the 35mm equivalent, multiply that effective focal length by the crop factor. For example, a 200mm lens with a 1.4x teleconverter becomes 280mm effective, and on an APS-C 1.5x body the equivalent is 420mm.