Desk Lighting Calculator

How this calculator works

Desk lighting is task lighting: it supplements ambient room light so your immediate work surface reaches a comfortable illuminance without glare on your monitor or harsh shadows on paper. This calculator focuses on the desk footprint — width and depth in centimeters or inches — and the type of work you perform. Each task type maps to a recommended lux range based on common ergonomic and workplace guidance. Computer work typically targets 300–500 lux on the keyboard and documents area; reading and writing often aim for around 500 lux; drawing, design, and crafting may need 750 lux or more.

The core formula mirrors room lighting: lumens on the work surface ≈ lux × desk area in square meters. A 120 cm × 60 cm desk has an area of 0.72 m². At 400 lux (mid-range for computer work), the surface needs about 288 lumens of illuminance distributed across that plane. In practice, a desk lamp or monitor light bar does not deliver all its lumens onto the desk — some spill to walls and ceiling. The calculator applies a simplified multiplier so suggested lamp output is higher than the bare lux × area result, giving a practical range for product selection.

Existing ambient light matters. If your room already provides 200 lux from ceiling fixtures, you need less additional task light to reach 500 lux on the desk than you would in a dim room. The optional ambient level field helps you think about balance: task plus ambient should meet the target without over-lighting the screen. For video calls, moderate frontal fill (300–500 lux equivalent on your face) often works better than a single harsh overhead source that creates eye shadows.

Color temperature recommendations vary by task. Neutral 4000K suits most office-style desk work and video. Reading at home may feel better at 3500K–4000K. Design and color work often benefit from 4000K–5000K with high CRI. The calculator suggests a range and lamp type — monitor light bar, dimmable desk lamp, adjustable task arm — aligned with each task preset. These are planning hints, not product endorsements.

Glare control is as important as brightness. Position task lights to the side of your screen, use diffusers, and prefer dimmable fixtures so you can match screen luminance to paper and keyboard. A monitor light bar reduces contrast between a bright display and a dark desk area but may not replace ambient light for paper tasks. Gaming setups sometimes deliberately use lower illuminance (200–400 lux) with bias lighting to reduce eye fatigue during long sessions — the preset reflects that use case.

Results are simplified estimates. Real desk illuminance depends on lamp height, beam angle, shade geometry, and room reflectance. Use the output to compare desk lamps (e.g., 800–1200 lm dimmable LED) or to verify that your current setup is in the right ballpark before upgrading equipment.

This calculator provides a simplified estimate for general planning. Actual lighting design may vary based on fixture distribution, ceiling height, reflectance, layout, glare control, local standards, and professional requirements.

Recommended lux levels by task

The following ranges match the task presets in the calculator. Adjust within the range based on age, contrast needs, and how much ambient light you already have.

Example calculations

Computer desk 120 cm × 60 cm: Area 0.72 m². Target 300–500 lux → roughly 216–360 lm on the surface; a dimmable lamp or monitor bar rated around 800–1200 lm is often practical after accounting for spill and dimming headroom.

Drawing desk 150 cm × 75 cm at 750 lux: Area 1.125 m² → about 844 lm on the plane before multiplier. Choose a high-CRI adjustable arm lamp with wide, even beam coverage.

Video call setup: Aim for soft 4000K–5000K fill at roughly 300–500 lux on your face; avoid strong backlight from windows without frontal light. Pair with moderate room ambient so the camera sees balanced exposure.

Planning whole-room lighting? Use the Office Lighting Calculator for ceiling fixtures, then return here to size desk task light.