Natural Light Calculator
Discover how much natural light your room receives and get personalized recommendations to brighten your space
Based on Met Office average annual sunshine hours
Account for nearby buildings, trees, or other obstructions
Enter your room dimensions and glazing details, then click "Calculate Natural Light" to see your results
Understanding Natural Light
What is Daylight Factor?
Daylight Factor (DF) is the ratio of internal light level to external light level, expressed as a percentage. It's the standard measure used by architects and building regulations to assess natural lighting.
- Below 2%: Room appears gloomy, artificial light needed most of the day
- 2-5%: Adequate for most activities but may feel dim
- 5-10%: Well-lit space, comfortable for work and living
- Above 10%: Excellent daylight, may need solar control
Tips for Better Natural Light
- South-facing glazing receives the most direct sunlight throughout the day
- Rooflights provide up to 3x more light than vertical windows of the same size
- Ultra-slim frames maximize glass area for more light transmission
- Light-coloured interiors reflect and distribute natural light better
Important Notice: This calculator provides approximate estimates for general guidance only. The results are purely indicative and should not be relied upon for architectural planning, building regulations compliance, or any professional decision-making. Actual daylight levels depend on numerous factors including external obstructions, glass specifications, weather conditions, and geographic location that this simplified tool cannot account for. For accurate assessments, please consult a qualified architect or glazing specialist. Shard Architectural Glazing accepts no liability for decisions made based on these calculations.