TidyFactPractical calculators, checked factsCrop factor and equivalent focal length calculator
Equivalent focal length = lens focal length × crop factor. APS-C is about 1.5× (Canon about 1.6×), and Four Thirds is about 2×. Example: a 33mm lens on an APS-C camera gives about the same angle of view as 50mm on full frame.
Last fact-checked: , by a separate, independent AI agent (Claude) against the official sources
You can also type the focal length, e.g. 33 or 18.5.
With an APS-C-only lens, the body can crop automatically. Example: on the Canon EOS R6 Mark II, RF-S and EF-S lenses give approx. 1.6 times the indicated focal length[11]. In that case, select APS-C.
- Crop factor
- ×1.53
- Equivalent aperture (DOF)
- f/2.1
- Angle of view (diagonal)
- 46°
- Angle of view (H×V)
- 39°×27°
Exposure is still f/1.4. The equivalent aperture only compares depth of field.
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Example
A 33mm lens on the X-T5 (23.5×15.7 mm): crop factor 1.53, about 51mm equivalent. Fujifilm lists it as 50mm.
Common mistake
The equivalent aperture is not exposure. An f/1.4 lens on Four Thirds still exposes at f/1.4; only the depth of field is close to f/2.8 on full frame.
Next step
To mount an old lens on a new body, use the “Lens Adapter Compatibility Chart”.
Crop factor by sensor format
Sizes come from the maker's specifications for one representative camera. The full-frame row uses the 36×24 mm reference for the conversion; the camera's actual size is in brackets. Other cameras can have a different size. You can enter it under “Custom size”.
| Format | W×H (mm) | Crop factor | Area | Example camera |
|---|---|---|---|---|
| Large medium format (53×40) | 53.4×40 | ×0.65 | 247% | Hasselblad H6D-100c[13] |
| Medium format (44×33) | 43.8×32.9 | ×0.79 | 167% | FUJIFILM GFX100 II / Hasselblad X2D II 100C[5][12] |
| Full frame (35mm) | 36×24 | ×1.00 | 100% | Canon EOS R6 Mark II (35.9×23.9)[2] |
| APS-C (about 1.5×) | 23.5×15.7 | ×1.53 | 43% | FUJIFILM X-T5[4] |
| APS-C (about 1.6×) | 22.3×14.9 | ×1.61 | 38% | Canon EOS R50[3] |
| Four Thirds (4/3) | 17.3×13 | ×2.00 | 26% | OM SYSTEM OM-1 Mark II[6] |
| 1-inch type | 13.2×8.8 | ×2.73 | 13% | Sony RX100 VII[7] |
What focal length matches a 50mm lens on full frame?
The table shows the real focal length that gives the same angle of view. Example: on APS-C (about 1.5×), about 33mm is close to 50mm on full frame.
| Full frame | Large medium format (53×40) | Medium format (44×33) | APS-C (about 1.5×) | APS-C (about 1.6×) | Four Thirds (4/3) | 1-inch type |
|---|---|---|---|---|---|---|
| 24 mm | 37 | 30.4 | 15.7 | 14.9 | 12 | 8.8 |
| 35 mm | 54 | 44.3 | 22.9 | 21.7 | 17.5 | 12.8 |
| 50 mm | 77.1 | 63.3 | 32.7 | 31 | 25 | 18.3 |
| 85 mm | 131.1 | 107.6 | 55.5 | 52.7 | 42.5 | 31.2 |
| 135 mm | 208.2 | 170.9 | 88.2 | 83.7 | 67.5 | 49.5 |
How it is calculated
- Crop factor = the full-frame (36×24 mm) diagonal of 43.27 mm ÷ the diagonal of this sensor[10].
- Equivalent focal length = real focal length × crop factor. It only means the same angle of view; the lens itself does not change[1].
- Angle of view = 2 × arctan(side ÷ 2 ÷ focal length). This tool assumes focus at infinity. It does not calculate the change in angle of view at close focus.
- Equivalent aperture = f-number × crop factor. At the same angle of view and subject distance, the depth of field is close to full frame at this f-number.
- Exposure does not change: OM SYSTEM describes the 150-400mm F4.5 as equivalent to 300–800mm F4.5[6]; the f-number is not doubled.
Checked against maker figures: Fujifilm lists the XF33mm as 50mm equivalent with a 46.6° angle of view[8]; this tool gives 51mm and a 46.4° diagonal angle of view. Fujifilm lists the GF63mm as 50mm[9]; this tool gives 50mm.
Cases not covered
- Video and crop modes crop the sensor again. Example: the GFX100 II lists 1.1× and 1.21× for some video formats[5]. Multiply the two factors.
- This tool does not switch to APS-C when a full-frame body uses an APS-C-only lens. Example: on the EOS R6 Mark II, RF-S and EF-S lenses give approx. 1.6 times the indicated focal length[11]. Select APS-C yourself.
- Phones are not included: each phone has a different sensor size.
- The formula does not apply to anamorphic or fisheye lenses.
- 120 film (6×4.5, 6×6, 6×7) is not included yet. Use Custom size and enter the frame size.
Frequently asked questions
What is a 50mm lens on APS-C equivalent to on full frame?
About 75mm (1.5×). Canon APS-C is about 1.6×, so about 80mm. This page uses the EOS R50 size and shows 81mm. Only the angle of view changes; the lens itself does not.
Why does APS-C have both 1.5× and 1.6×?
Makers use different sensor sizes. The Canon EOS R50 is 22.3×14.9 mm, about 1.6×. The Fujifilm X-T5 is 23.5×15.7 mm, about 1.53×, usually written as 1.5×.
Does the equivalent aperture make photos darker?
No. Exposure follows the lens's f-number: an f/1.4 lens on a Four Thirds camera still exposes at f/1.4. An equivalent aperture of f/2.8 only means the depth of field is close to f/2.8 on full frame.
Is a 1-inch type sensor one inch across?
No. The 1-inch type sensor in the Sony RX100 VII is 13.2×8.8 mm, with a diagonal of about 15.9 mm, much smaller than 1 inch (25.4 mm).
Why is the crop factor of medium format less than 1?
Medium format is larger than full frame. The GFX100 II is 43.8×32.9 mm, a crop factor of about 0.79, so a 63mm lens has about the angle of view of 50mm on full frame. The Hasselblad X2D II 100C sensor is also 43.8×32.9 mm. The Hasselblad H6D-100c is larger, at 53.4×40.0 mm.
Sources
- What Is Crop Factor? How It Changes What Your Lens Does (Nikon Asia, checked 2026-10-24)
- Canon EOS R6 Mark II Specifications (Canon Europe, checked 2026-10-24)
- Canon EOS R50 Specifications (Canon Europe, checked 2026-10-24)
- FUJIFILM X-T5 Specifications (FUJIFILM, checked 2026-10-24)
- FUJIFILM GFX100 II Specifications (FUJIFILM, checked 2026-10-24)
- OM-1 Mark II (OM SYSTEM, checked 2026-10-24)
- DSC-RX100M7 Specifications (Sony UK, checked 2026-10-24)
- XF33mmF1.4 R LM WR Specifications (FUJIFILM, checked 2026-10-24)
- GF63mmF2.8 R WR Specifications (FUJIFILM, checked 2026-10-24)
- What is crop factor and how do I calculate it? DX and FX explained (Nikon UK, checked 2026-10-24)
- EOS R6 Mark II Product Manual: Specifications (Canon, checked 2026-10-24)
- X2D II 100C Datasheet (Hasselblad, checked 2026-10-24)
- H6D-50c/H6D-100c Datasheet (Hasselblad, checked 2026-10-25)
How we made this page
AI helped make this page. We first read the official sources. Then we wrote the calculation rules and the text. After that, a separate, independent AI agent (Claude) checked the page against the sources (2026-10-24). No person reviewed this page.
Crop factor = the full-frame (36×24 mm) diagonal of 43.27 mm ÷ the diagonal of the sensor. Each format uses the maker's specified size for one representative camera. Other cameras can have a different size.
Checked against maker figures: Canon states 1.6× for the EOS R50, Nikon states 1.5× for APS-C and OM SYSTEM states 2× for Four Thirds. Fujifilm lists the XF33mm as 50mm equivalent with a 46.6° angle of view (this tool gives a 46.4° diagonal angle of view) and the GF63mm as 50mm (2026-10-24).
The angle of view assumes a rectilinear lens focused at infinity. This tool does not calculate the change in angle of view at close focus.
The equivalent aperture is this tool's own conversion (similar depth of field at the same angle of view and subject distance), not a maker specification. Exposure still follows the lens's f-number: OM SYSTEM describes the 150-400mm F4.5 as equivalent to 300–800mm “F4.5”.
The simulated view is an illustration: a person 8 m away and trees 30 m away, with blur estimated by the thin-lens formula. It does not show the rendering of any real lens.
Last updated: 2026-10-24
Cite this page
TidyFact. (2026, October 24). Crop Factor and Equivalent Focal Length. https://tidyfact.com/camera/en/crop-factor-calculator/