Input parameters
Results
Enter values and choose a mode, then calculate.
Calculated scenarios
Each calculation is added to this table for exporting.
| # | Mode | Distance | Coverage width | Beam angle (deg) | Mounting height | Offset | Aiming angle (deg) |
|---|
Example lighting angle scenarios
Use these sample values to understand how beam angle, coverage, and distance interact.
| Scenario | Distance (m) | Coverage width (m) | Beam angle (°) | Notes |
|---|---|---|---|---|
| Desk spotlight | 1.0 | 0.6 | 34.4 | Narrow beam to avoid spilling onto surrounding walls. |
| Accent wall wash | 2.5 | 3.0 | 65.6 | Wide beam for even coverage across a feature wall. |
| Hallway downlight | 2.4 | 1.2 | 28.1 | Medium beam to keep light focused along the path. |
Formula used
The calculator uses basic trigonometry between the light source, target plane, and beam edges.
- Beam angle from coverage width and distance:
θ = 2 × atan(W / (2D)), where W is coverage width and D is distance. - Coverage width from beam angle and distance:
W = 2D × tan(θ / 2). - Distance from beam angle and coverage width:
D = W / (2 × tan(θ / 2)). - Vertical aiming angle from offset and height:
α = atan(O / H), where O is horizontal offset and H is mounting height.
Angles are calculated internally in radians and converted back to degrees for readability.
How to use this calculator
- Select the preferred unit system so values are consistent.
- Choose the calculation mode that matches your design question.
- Enter the known values, such as distance and required coverage width.
- Optionally add mounting height and offset to calculate aiming angle.
- Click Calculate angle to see the results and key metrics.
- Review the scenario table; each run is added as a new row.
- Use CSV or PDF export buttons to share or archive your calculations.
Design guidance based on lighting angles
1. Typical beam angles for common rooms
Living rooms commonly use medium beams around 30–40°, while kitchens and task areas often work better with slightly narrower 20–35° beams. Wide beams above 50° suit general ambient lighting and soft wall washing.
2. Mounting height and spacing relationship
For ceiling downlights, a simple rule is spacing roughly equal to mounting height. Use the calculated coverage width to refine spacing so beam edges meet or slightly overlap without leaving dark patches between fittings.
3. Aiming angle for task lighting
Use the tilt mode with mounting height and offset to find a comfortable aiming angle. Keeping the beam between about 25° and 45° from vertical helps reduce glare while still highlighting worktops or artwork effectively.
4. Coordinating with recessed lighting costs
After choosing beam angles and spacing, you can estimate fixture quantities and labor using the Cost to Install Recessed Lighting Calculator. Combining geometry and cost helps balance comfort, appearance, and budget in one workflow.
5. Balancing natural light with artificial light
Window treatments affect how much daylight enters a room. Use this tool alongside the Curtain Size Calculator to coordinate curtain coverage, daylight control, and electric light beam spreads for flexible scenes.
6. Checking glare and visual comfort
Very narrow beams at shallow angles can cause harsh glare. If occupants see bright sources directly, try increasing mounting height, widening the beam, or aiming slightly away from eye level while keeping coverage adequate on the target plane.
Frequently asked questions
1. What does this lighting angle calculator do?
It relates beam angle, mounting distance, and coverage width using basic trigonometry. You can solve for whichever variable is missing and estimate aiming angle for fittings that are offset from the area you want to illuminate.
2. Which units can I use for distances?
The calculator supports meters and feet. Choose one unit at the top, then keep every entry in that same unit so results remain consistent. You can switch units at any time before entering new values.
3. Can I use this for wall washing or accent lighting?
Yes. Enter the distance from the light to the wall or object and either your preferred beam angle or desired coverage width. The tool then helps you aim fixtures and choose optics that avoid bright hot spots.
4. How accurate are the results?
Results are mathematically accurate for ideal, symmetrical beams. Real products may have softer edges and irregular distributions, so always check manufacturer photometric data or on-site tests before finalizing any critical lighting design decisions.
5. How should I estimate downlight spacing?
Start with spacing around the same as mounting height, then use the coverage mode to see where beams overlap. Adjust spacing until coverage width gives smooth light without visible dark bands between fixtures along the ceiling.
6. Why do I sometimes get unrealistic numbers?
Very small distances, extremely narrow angles, or very wide coverage requests can push the trigonometry into unrealistic ranges. Check that the inputs reflect real rooms and fixtures, then adjust angles or distances to more practical values.
7. Can I export results for my project file?
Yes. Every calculation adds a row to the scenarios table. Use the CSV button to analyze data in spreadsheets or the PDF button to archive results in project folders, design briefs, and client reports.