Macro Extension Magnification Calculator
Estimate extra magnification from an extension tube on a simple lens.
Your inputs
Calculation results
Formula & assumptions
Approximate added magnification = extension/focal length; lens focusing design can change the result.
Values use the specified units. Calculations use floating-point arithmetic. Check input measurements and formula assumptions before applying the result.
Compare your scenarios
Save up to five results to compare changes side by side. Scenarios stay in this tab until you clear or reload it.
Using Macro Extension Magnification Calculator
Estimate extra magnification from an extension tube on a simple lens.
- Enter lens focal length, extension length, original magnification using the units printed under each field.
- Choose Calculate, or enable live updates. Review the result labels and formula assumptions.
- Save scenarios to compare up to five variations, then copy the report or download JSON or CSV.
Example
Lens focal length: 50 millimeters Extension length: 25 millimeters Original magnification: 0.1 ratio Added magnification: 0.5 Approximate total magnification: 0.6
Questions & answers
What does Macro Extension Magnification Calculator calculate?
Estimate extra magnification from an extension tube on a simple lens.
Which units should I enter?
Lens focal length uses millimeters. Extension length uses millimeters. Original magnification uses ratio. Convert values to these units before calculating.
Which formula does it use?
Approximate added magnification = extension/focal length; lens focusing design can change the result.
What does the included example show?
Lens focal length: 50 millimeters; Extension length: 25 millimeters; Original magnification: 0.1 ratio. Result: Added magnification = 0.5; Approximate total magnification = 0.6.
Can I compare different settings?
Yes. Save a scenario, change the inputs and save another result. Up to five scenarios are compared in this tab; they disappear when you reload or leave.
Can I export the calculation?
Copy the JSON report or download JSON and CSV with inputs, result labels and numeric values. Processing uses local JavaScript; no calculation request is sent to our server. Displayed values use up to 10 significant digits; exports retain JavaScript numeric precision.
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