Extech LT300 Luxmeter, 0 til 400 000 lx

Lighting technicians, facility managers, and workplace safety inspectors use the Extech LT300 to verify illumination levels in offices, warehouses, and production areas. Its wide 0 to 400,000 lux range covers everything from dim emergency lighting to bright outdoor sunlight, with foot-candle readings for legacy specifications.

Key specifications

• Measurement range: 0 to 400,000 lux / 0 to 40,000 foot-candles
• Accuracy: ±5% of reading + 10 digits (CIE standard incandescent lamp, 2856K)
• Resolution: 0.1 lx (0–199.9 lx), 1 lx (200–1999 lx), 10 lx (2000–19999 lx), 100 lx (20000–400000 lx)
• Sensor: Silicon photodiode with spectral response filter, CIE photopic response
• Sampling rate: 2.5 times per second
• Functions: Data hold, min/max, auto power off (disable option)
• Display: 4000-count LCD with over-range and low-battery indication
• Power: 9V battery
• Operating conditions: 0 to 50°C, 10 to 90% RH non-condensing
• Tripod mount for hands-free measurement

Why choose it

The LT300’s silicon photodiode with spectral response filter closely matches the human eye’s sensitivity, so readings reflect perceived brightness rather than raw optical power. Min/max capture helps identify uneven lighting or intermittent fluctuations, and the tripod mount allows stable, repeatable measurements in fixed locations.

Ideal use cases

• Workplace safety audits to verify minimum illumination levels
• Lighting design and retrofit projects
• Museum and gallery light exposure monitoring
• Greenhouse and horticultural light management

Good to know

The meter switches between lux and foot-candles with a single button, and the auto power off can be disabled for long-term logging sessions. A 9V battery provides convenient field replacement.