APS-C Crop Factor Calculator

Calculator

Camera sensor preset

Lens focal length, mm

Aperture f-number

Sensor width, mm

Sensor height, mm

Optional crop factor override

Reference width, mm

Reference height, mm

Subject distance, meters

Reference circle of confusion, mm

Example Data Table

Camera type	Sensor size	Lens	Approx crop	Equivalent focal length
Canon APS-C	22.3 × 14.9 mm	50 mm	1.61x	80.5 mm
Nikon APS-C	23.5 × 15.6 mm	35 mm	1.53x	53.6 mm
Fujifilm APS-C	23.5 × 15.6 mm	23 mm	1.53x	35.2 mm
Custom APS-C	24.0 × 16.0 mm	85 mm	1.50x	127.5 mm

Formula Used

Sensor diagonal = √(sensor width² + sensor height²)

Reference diagonal = √(reference width² + reference height²)

Crop factor = reference diagonal ÷ sensor diagonal

Equivalent focal length = actual focal length × crop factor

Depth of field equivalent aperture = f-number × crop factor

Field of view = 2 × atan(sensor dimension ÷ 2f)

Hyperfocal distance = f² ÷ (N × c) + f

How To Use This Calculator

Select a sensor preset or enter custom APS-C dimensions.

Enter the real lens focal length and aperture.

Keep the reference size at 36 × 24 mm for full frame comparison.

Enter subject distance for depth of field estimates.

Use the optional crop override when your camera maker gives a known crop value.

Press calculate to view results above the form.

Use the CSV or PDF buttons to save the current report.

Understanding APS-C Crop Factor

APS-C cameras use a smaller sensor than the classic 35 mm frame. The lens still projects the same image. The sensor records a smaller center area. This narrower capture changes framing. It does not multiply the glass. It changes the angle of view.

Why Crop Factor Matters

Crop factor compares two sensor diagonals. A full frame sensor is usually 36 mm by 24 mm. Many APS-C sensors are near 23.5 mm by 15.6 mm. The diagonal ratio is about 1.5. Canon APS-C bodies are often close to 1.6. This number helps photographers compare lenses across systems.

A 50 mm lens on a 1.5 crop body frames like a 75 mm lens on full frame. Wildlife shooters gain tighter framing without cropping later. Landscape shooters notice that wide lenses feel less wide. Portrait shooters can plan working distance more clearly.

What The Calculator Shows

This calculator reports crop factor, equivalent focal length, equivalent depth of field aperture, and field of view. It also estimates hyperfocal distance when subject distance is entered. These values help with lens choice, framing, and shot planning.

Equivalent focal length is only a framing guide. Exposure does not change because of crop factor. An f/2.8 lens still exposes as f/2.8. Depth of field comparison is different. For a similar print size and framing, multiply aperture by crop factor. That gives a practical depth of field equivalent.

Practical Use Cases

Use the tool before buying a lens. Check if a 35 mm lens will act like a normal lens. Compare a 10 mm ultra wide with a 16 mm full frame view. Estimate how much background blur changes between bodies. Review field of view before a product shoot, property shoot, or travel trip.

Advanced Tips

Sensor dimensions vary by brand. Always enter the actual sensor size when accuracy matters. Use diagonal field of view for quick comparison. Use horizontal field of view for panoramas and video framing. Use vertical field of view for portraits and tall products.

Crop factor is simple, but it affects many choices. Good estimates reduce guesswork. They also make lens comparisons cleaner and faster.

Keep saved reports for client notes, location scouting, equipment checks, rental planning, and repeat studio setups.

FAQs

Does crop factor really change focal length?

No. The lens focal length stays the same. Crop factor only changes the recorded angle of view because the sensor captures a smaller part of the image circle.

Why is Canon APS-C often different?

Canon APS-C sensors are usually slightly smaller than many Nikon, Sony, and Fujifilm APS-C sensors. A smaller diagonal gives a larger crop factor.

Does crop factor change exposure?

No. An f/2.8 lens still exposes as f/2.8. Crop factor is useful for framing and depth of field comparisons, not exposure brightness.

What is equivalent aperture?

Equivalent aperture compares depth of field across formats. Multiply the f-number by crop factor when similar framing and output size are assumed.

Which sensor size should I enter?

Use your camera model’s actual sensor width and height. Small differences can slightly change crop factor, field of view, and lens comparisons.

Can I use this for full frame lenses?

Yes. A full frame lens on an APS-C body still uses the same focal length. The smaller sensor records a cropped field of view.

What is field of view?

Field of view is the angle captured by the sensor and lens combination. Wider sensors or shorter focal lengths give wider views.

Why include circle of confusion?

Circle of confusion helps estimate hyperfocal distance and depth of field. The calculator scales it from the reference format using crop factor.