Converters & Utilities

Percent ↔ Decimal Converter

Convert between percentage and decimal form — used throughout lighting calculations for CU, LLF, dimming levels, efficiency ratings, and reflectance values.

Percent

⇄

Decimal

0.700

decimal

Visual Representation

70%

In CU / LLF Calculation

As multiplier× 0.700

E = (Lm × CU × LLF) / Astandard form

1000 lm × this700 lm

100 lm/W × this70 lm/W eff.

Dimming Context

Dim level70%

0–10V signal7.0 V

PWM duty cycle70%

DALI arc level178 / 254

Practical Notes

Lighting calculations use many factors written as percentages, such as the coefficient of utilization, the light loss factor, reflectance, efficiency, and dimming level, but formulas need them as decimals. To convert a percentage to a decimal, divide by 100, so 70 percent becomes 0.70, and to go back, multiply by 100. Moving the decimal point two places is all that is needed.

A typical calculation shows why this matters. The lumens required equal the target illuminance multiplied by the area, divided by the product of the coefficient of utilization and the light loss factor. For 500 lux over 100 square meters with a utilization of 0.70 and a loss factor of 0.85, you need about 84,000 lumens.

The most common mistake is to enter a percentage as a whole number, such as 70 instead of 0.70, which gives results that are off by a factor of one hundred. Another is to confuse a half of a percent with a half, since 0.5 percent is 0.005. Check that the answer looks sensible, and keep the same form throughout a calculation.