LensCalc

Crop Factor Calculator

How does your sensor compare to full frame?

Sensor Width (mm)

Sensor Height (mm)

Crop Factor

1.53x

Sensor Diagonal: 28.21 mm
50mm Equivalent: 76.7 mm

What you entered

Sensor Width (mm): 23.5Sensor Height (mm): 15.6

1
Full frame diagonal
sqrt(36^2 + 24^2)= 43.2666 mm
2
Sensor diagonal
sqrt(23.5^2 + 15.6^2)= 28.2066 mm
3
Crop factor
43.2666 / 28.2066= 1.5339x
4
50mm equivalent focal length
50 x 1.5339= 76.696 mm

Result

Crop Factor: 1.53x

Crop factor by sensor size

Crop factor is the full-frame diagonal (43.27 mm) divided by the sensor's diagonal. It tells you how much narrower a given lens sees on that sensor.

Sensor	Dimensions	Diagonal	Crop factor	A 50mm lens acts like
Medium format	44 x 33 mm	55.00 mm	0.79	39.3 mm
Full frame	36 x 24 mm	43.27 mm	1.00	50.0 mm
APS-C (Nikon/Sony)	23.5 x 15.6 mm	28.21 mm	1.53	76.7 mm
APS-C (Canon)	22.3 x 14.9 mm	26.82 mm	1.61	80.7 mm
Micro Four Thirds	17.3 x 13 mm	21.64 mm	2.00	100.0 mm
1-inch	13.2 x 8.8 mm	15.86 mm	2.73	136.4 mm

Crop factor changes the field of view, not the focal length or the aperture's light-gathering. A 50mm f/1.8 on APS-C still gathers f/1.8 worth of light; it just frames like an 80mm would on full frame.

Crop factor = full-frame diagonal ÷ sensor diagonal

A full-frame sensor is 36×24mm (diagonal ~43.3mm) — a typical APS-C sensor (~23.5×15.6mm, diagonal ~28.2mm) has a crop factor of about 1.5x, meaning a 50mm lens on it gives the field of view of a 75mm lens on full frame.

Crop factor affects more than framing

While crop factor describes the field-of-view change, it also affects the apparent depth of field — a smaller sensor at the same framing needs a shorter focal length, which gives more DOF, so crop sensors are slightly advantaged for landscape sharpness.

Frequently asked questions

My camera has a 1.5x crop factor and I'm using a 50mm lens — what's the equivalent focal length?

50 × 1.5 = 75mm equivalent field of view. You'd need a 75mm lens on a full-frame camera to get the same framing.

How is crop factor different from focal length equivalent?

Crop factor is the multiplier itself (e.g., 1.5x for APS-C). The focal length equivalent calculator applies that multiplier to a specific lens to give the 35mm-equivalent focal length — crop factor is the ratio, equivalent focal length is the result.

Does Micro Four Thirds really have a 2x crop factor?

Yes. The MFT sensor is 17.3×13mm (diagonal ~21.6mm) versus full frame's ~43.3mm diagonal, giving exactly 2x. A 25mm MFT lens gives the same framing as a 50mm on full frame.