Luminous Intensity Converter

Convert non-negative luminous intensity between candela, millicandela, kilocandela, lumen per steradian, candlepower, and Hefnerkerze.

Photometry

Convert luminous intensity across candela and historical source units

Restate point-source intensity values without mixing them up with luminance, illuminance, or total luminous flux.

Quick presets

Scope note

This page converts luminous intensity only. It keeps the source as a directional point-source quantity and does not estimate illuminance on a target or luminance from a glowing surface.

Enter values Provide a luminous intensity and source unit to calculate the full conversion sheet.

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Photometry

Luminous intensity converter: candela, millicandela, candlepower, and directional source units explained

A luminous intensity converter rewrites the same directional light-source quantity in the unit your LED note, photometric specification, or historical reference expects. That matters because source intensity is not the same as luminance, illuminance, or total luminous flux.

What luminous intensity measures

Luminous intensity describes luminous flux per unit solid angle in a given direction. It is the photometric quantity used for directional emitters, lamps, and beam-center specifications.

The same directional source value can be written as candela, millicandela, kilocandela, or lumen per steradian without changing the underlying quantity.

I = dΦv / dΩ

Defines luminous intensity as luminous flux per unit solid angle.

1 cd = 1 lm/sr

Shows the exact SI relationship used by this page.

1 kcd = 1,000 cd

Links the common source-intensity reporting scales supported here.

Why it is not the same as flux or illuminance

Luminous flux measures total emitted visible power, while luminous intensity keeps the directional piece explicit. Illuminance measures received light on a surface. Those are related quantities, but they are not interchangeable.

This page therefore converts only luminous-intensity units and leaves beam geometry, distance, and receiving-surface calculations to separate workflows.

Why historical source labels need caution

Historical references may use candlepower or Hefnerkerze in older photometric tables and lamp literature. Those are useful as reference labels, but they are not the modern SI standard.

The converter keeps candela as the explicit base so newer specifications and legacy references can be compared without blurring the quantity definition.

Further reading

Frequently asked questions

Is candela the same as lumen per steradian?

Yes. One candela is exactly one lumen per steradian.

 What is the difference between luminous intensity and luminous flux?

Luminous flux is total visible light output. Luminous intensity is that output distributed per unit solid angle in a given direction.

 Does this page convert lux or foot-candles?

No. Lux and foot-candles are illuminance units, which describe received light on a surface rather than source intensity.

 Why are candlepower and Hefnerkerze treated as historical labels?

They appear in older photometric references, but candela is the current SI standard. The page keeps those older labels for translation and reference only.

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