ISO Lumens vs ANSI Lumens: What’s the Difference?

When shopping for a projector, one of the key specifications to consider is lumens, the measurement of how bright the projected image will be. There are two main internationally recognized standards for rating projector brightness: ANSI lumens and ISO lumens.

So explain the differences between these two measurements and which one is brighter.

What is a Lumen?

A lumen is a unit of measurement that is used to show how strong or intense a light source is. It measures the total quantity of visible light emitted from a source in a particular beam or angle.

ANSI Lumens

ANSI lumens (American National Standards Institute) are the standard brightness measurement and most commonly used for projectors in the North American market. The ANSI lumen rating measures the total light output of a projector. To test this, a full white image is projected and the brightness of the white screen is measured at different points.

The ANSI lumens rating is useful for comparing the maximum brightness between different projector models. A higher ANSI lumen rating means the projector can produce a brighter picture. Light output can range from under 100 ANSI lumens for pocket projectors to over 10,000 lumens for high-end professional projectors.

ISO Lumens

ISO lumens (International Organization for Standardization) represent a more realistic brightness measurement. Rather than using a full white test image, the ISO test uses a checkerboard pattern of black and white squares. This better simulates the type of varied images that will be projected in real world applications.

The ISO lumen rating measures the average light output across the test pattern. This results in a lower lumen measurement versus the ANSI test. On average, the ISO lumen rating is about 20% less than the ANSI rating.

ISO Lumens vs ANSI Lumens Conversion

Provided the brightness of a projector is fixed, the ANSI lumen is a larger and therefore brighter measurement than ISO lumen.

The conversion ratio between ANSI lumen and ISO lumen (ISO21118) is 1 ANSI lumen to 0.8 ISO Lumens.

Andrew Orange, the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.