How to Calculate Extension Tube Magnification
Extension tubes are one of the cheapest ways to get into macro photography. They increase magnification by moving your lens farther from the camera sensor, letting you focus closer to your subject.
There are two main ways to calculate the magnification you’ll get:
🟢 Simple Extension Tube Calculator
Perfect for beginners who just want a quick number.
👉 Enter lens focal length (mm) and extension tube length (mm) — both are printed on your gear.
The result is your added magnification ratio (e.g., 0.5× or 1:2).
Simple Extension Tube Calculator
Shows added magnification only (ignores native lens magnification).
🔵 Advanced Extension Tube Calculator
Made for photographers who want more accuracy.
👉 In addition to focal length and extension length, this version also requires your lens’s minimum focusing distance (MFD), which you’ll usually find in the lens specifications or by checking online.
The result is your total magnification ratio (native magnification + added magnification).
Extension Tube Magnification Calculator
Enter your lens focal length, extension tube length, and minimum focusing distance (MFD). This will calculate the total magnification including your lens’s native ability and the added extension.
📲 Try it yourself: use the [Simple Calculator] if you just want a quick result with the numbers printed on your lens and extension tube, or the [Advanced Calculator] if you want precise total magnification using your lens’s MFD.
