About Lighting Calculator

Who this site is for

Lighting Calculator is built for the people who make lighting decisions: electricians and lighting installers, contractors pricing a fixture schedule, facility and energy managers running buildings, designers sizing a first layout, and owners who want to know what they are paying for.

Why it exists

Lighting numbers are easy to get slightly wrong: lumens on the box against lux on the surface, a fixture count that ignores the maintenance factor, a spacing that looks even but leaves dark bands, a power density that misses the driver losses, or a retrofit payback built on assumed instead of measured hours. Those small errors turn into callbacks, failed inspections, and savings that never appear. This site exists to make the arithmetic checkable in minutes, with every assumption visible on the page.

What you will find here

• Calculators with visible math: every input, formula, and output is shown, so a result can be checked by hand or against the photometric file and the code tables.
• Reference tables in the open: illuminance targets, maintenance factors, source efficacy, and allowance values, each labelled with where it came from and what it assumes.
• Practical guides: worked examples that pair a parameter table with the arithmetic behind it, written to be reproduced on paper.
• A private Workspace: save assumptions and reports for projects, quotes, and comparisons without exposing client data.

How content is produced and reviewed

Each calculator ships with machine-checked test cases: fixed inputs must reproduce fixed outputs before the tool is published. Energy price baselines carry a data year and are reviewed annually against U.S. Energy Information Administration figures. Illuminance targets and allowance values state the practice they came from. Guides cite their sources and show the full arithmetic of every worked example. When a reader reports an error through Contact, the page is corrected and the correction is noted.

What this site is not

Lighting Calculator is a planning and reference tool. It is not a substitute for a photometric study, the adopted energy code, the illumination standard the project is designed to, manufacturer data, or the judgment of a qualified lighting professional on site. A calculator output is not an approval, a permit, a quote, or a guarantee of performance. Read the Disclosure before relying on any result.

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Read the methodology · Read the disclosure · Contact the site