Crop Factor Explained: Full Frame, APS-C & M4/3 Equivalents | ShutterMath
What crop factor really means: focal length and aperture equivalence computed for full frame, APS-C, Micro 4/3 and phone cameras — and why exposure doesn't change.
Crop factor is the diagonal of a full-frame sensor (43.27 mm) divided by your sensor's diagonal. It answers one question: how does my lens frame and blur compared with the same lens on full frame?
Real crop factors, computed from sensor dimensions
| Camera | Sensor | Crop factor |
|---|---|---|
| Sony A1 II | 36.0 × 24.0 mm | 1.00× |
| Sony A6700 | 23.5 × 15.6 mm | 1.53× |
| Canon EOS R7 | 22.3 × 14.9 mm | 1.61× |
| Fujifilm X-T5 | 23.5 × 15.6 mm | 1.53× |
| OM System OM-1 II | 17.4 × 13.0 mm | 1.99× |
| iPhone 16 Pro | 9.8 × 7.3 mm | 3.54× |
Focal length equivalence (same framing)
A lens on a smaller sensor frames like a longer lens on full frame. To match full-frame framing, multiply the focal length by the crop factor:
| Lens | Full frame | APS-C 1.52× | Canon APS-C 1.6× | M4/3 2× | Phone 3.6× |
|---|---|---|---|---|---|
| 24 mm | 24 mm | 36 mm | 38 mm | 48 mm | 86 mm |
| 35 mm | 35 mm | 53 mm | 56 mm | 70 mm | 126 mm |
| 50 mm | 50 mm | 76 mm | 80 mm | 100 mm | 180 mm |
| 85 mm | 85 mm | 129 mm | 136 mm | 170 mm | 306 mm |
| 135 mm | 135 mm | 205 mm | 216 mm | 270 mm | 486 mm |
Aperture equivalence (same depth of field)
To match full-frame depth of field and background blur, multiply the aperture too. 50 mm f/1.8 on APS-C behaves like 75 mm f/2.7 on full frame — same framing, same blur:
| On this camera | Equivalent on APS-C (1.5×) | Equivalent on full frame |
|---|---|---|
| 50 mm f/1.8 | 75 mm f/2.7 | 100 mm f/3.6 |
| 35 mm f/1.4 | 52 mm f/2.1 | 70 mm f/2.8 |
| 85 mm f/1.2 | 128 mm f/1.8 | 170 mm f/2.4 |
Full-frame users need 2× the focal length of M4/3 users, but also 2× the f-number for the same look. Compute your exact rig in the free depth of field calculator or field of view calculator.
Related tools & guides
Field of View Calculator
Angles of view for any sensor and lens, with equivalents.
Open →Depth of Field Calculator
DoF for your exact camera — no crop approximations.
Open →Camera Sensor Sizes
All formats compared side by side.
Read →Crop factor FAQ
What is crop factor?
Full-frame diagonal (43.27 mm) ÷ your sensor diagonal. APS-C ≈ 1.5×, Canon APS-C ≈ 1.6×, Micro 4/3 = 2×.
Does crop factor change exposure?
No — never. Same aperture, shutter and ISO = same exposure on any format. Crop factor only changes framing and depth of field.
Do lenses change focal length on crop sensors?
No. A 50 mm lens is always 50 mm. It just frames like a 75 mm would on full frame.