Calculate equivalent focal length across sensor sizes — full frame, APS-C, Micro Four Thirds, medium format, and phone cameras. Compare field of view and depth of field.
The Focal Length Equivalent Calculator converts focal lengths between different camera sensor formats using crop factors. Enter any focal length and see the full-frame equivalent, the resulting field of view, and the depth-of-field-equivalent aperture across sensor sizes from medium format to smartphone. It is a practical shortcut for comparing lenses before you commit to a camera system or a new lens purchase.
Sensor size affects how much of the lens's image circle is captured. A smaller sensor uses only the center portion of the image, effectively "cropping" the view and making it appear more telephoto. A 50mm lens on an APS-C camera (1.5× crop) frames like a 75mm lens on full frame. Understanding this equivalence is crucial for choosing lenses and achieving specific compositions.
This tool goes beyond simple multiplication. It calculates field of view in degrees, the aperture needed to match depth of field across formats, and provides a reference of common lenses with their equivalents on major sensor sizes.
Use this calculator when you want a crop-factor comparison before buying or mounting a lens on a different camera system. It is useful for choosing focal lengths, estimating framing, and matching depth of field across sensor sizes. That makes it easier to predict the look of a shot before you switch formats or rent a lens.
Equivalent FL = Actual FL × (Target Crop / Source Crop). Field of View = 2 × arctan(sensor width / (2 × focal length)). DOF-equivalent aperture = actual aperture × crop factor.
Result: 75mm full-frame equivalent
50mm × 1.5 crop factor = 75mm equivalent. On APS-C, a 50mm lens frames like a 75mm on full frame. For matching DOF, f/1.8 on APS-C ≈ f/2.7 on full frame.
The "full frame" standard (36×24mm) comes from 35mm motion picture film. It became the reference point for focal length equivalence. Anything smaller is "crop" and anything larger is "medium format."
APS-C (~23.5×15.6mm for Nikon/Sony, ~22.3×14.9mm for Canon) captures about 44% of the area of full frame. Micro Four Thirds (17.3×13mm) captures about 25%. A smartphone sensor (1/1.3" ≈ 9.6×7.2mm) captures only about 8% of a full-frame sensor area.
Instead of memorizing crop factors, learn the visual effect: On APS-C, a 35mm feels like a 50mm "standard" view. A 23mm feels like a 35mm "documentary" view. A 56mm feels like an 85mm "portrait" view. On MFT, a 25mm ≈ 50mm, 42.5mm ≈ 85mm, 12mm ≈ 24mm.
Larger sensors offer shallower DOF, better low-light performance, and higher resolution. Smaller sensors enable smaller/lighter bodies and lenses, greater effective reach for wildlife/sports, and deeper DOF (useful for landscapes). Neither is objectively "better" — it depends on your photographic priorities.
Crop factor is the ratio of a full-frame sensor diagonal (43.3mm) to the diagonal of a smaller sensor. APS-C ≈ 1.5× (Nikon/Sony) or 1.6× (Canon). Micro Four Thirds = 2×. A 1-inch sensor ≈ 2.7×.
No. A 50mm lens is always 50mm regardless of the sensor. Crop factor describes the change in field of view and effective framing compared to full frame. The lens's optical properties don't change.
Phone sensors are tiny (crop factor 5-8×), so a 5mm lens provides the same field of view as a 24mm lens on full frame. The "equivalent" label helps users compare framing to traditional cameras.
Indirectly, yes. A smaller sensor at the same framing uses a shorter actual focal length, producing deeper DOF. To match full-frame DOF, multiply the aperture by the crop factor: f/2.8 on APS-C ≈ f/4.2 DOF on full frame.
Medium format sensors are larger than "full frame" (which is really just 35mm film frame). They have crop factors less than 1 (0.79× for Fuji GFX). This gives shallower DOF and wider FOV at the same focal length.
The "normal" lens roughly equals the sensor diagonal. Full frame: ~43mm (practically 50mm). APS-C: ~28mm (practically 35mm). MFT: ~22mm (practically 25mm). Medium format: ~55mm (practically 80mm).