How to Calculate Lumens Per Watt

LED Wattage for Replacing Existing Lighting

This question comes up constantly in our lighting consultations. Most people instinctively compare wattages when switching to LED, but this approach will lead you astray. Focus on lumens instead—the actual light output you’re getting. In LED technology, watts represent energy consumption while lumens measure light production. Different LED products convert watts to lumens with dramatically different efficiency levels. Not all LEDs deliver equal performance per watt consumed, which directly impacts your operating costs and light quality.

Replacing Metal Halide Watts with LED

Consider a common warehouse scenario: replacing a 250-Watt metal halide low bay fixture. After 17 years designing commercial lighting systems, I’ve seen countless facilities make this exact upgrade.

Our High Bay LED Fixtures deliver 130 to 160 lumens per watt—a crucial efficiency range that determines your long-term energy savings.

Take our 120-Watt UFO Low Bay producing 18,000 lumens. A competitor’s fixture using older LED chips operates at just 120 lumens per watt. Their comparable low bay generates only 12,000 lumens. Matching our light output would require 125 Watts of their product.

This example illustrates why wattage comparisons mislead customers completely. When facility managers call asking “How many watts replace my 250-Watt Metal Halide?”, we recommend 100 Watts while competitors suggest 125 Watts. The conversation must shift to lumens and efficiency—the metrics that actually matter for performance and cost.

Here’s the financial impact: our Low Bay Lights match competitor output while consuming 25 fewer watts per fixture. Multiply that across dozens or hundreds of fixtures, and you’re looking at substantial monthly electricity savings. Higher efficiency means lower operating costs throughout the fixture’s lifespan.

The LED market varies tremendously in quality and performance. Study the specifications carefully, calculate lumens per watt, and remember that superior efficiency translates directly to reduced energy expenses and better return on investment.

Lumens Guidelines

Based on thousands of successful conversions, these ranges provide reliable replacement targets for different applications:

Indoor Fixtures

• 250 Watts HID: 10,000 – 14,000 LED Lumens
• 400 Watts HID: 15,000 – 30,000 LED Lumens
• 1000 Watts HID: 40,000+ LED Lumens

Outdoor Fixtures

• 250 Watts HID: 7,000 – 15,000 LED Lumens
• 400 Watts HID: 15,000 – 30,000 LED Lumens
• 1000 Watts HID: 40,000+ LED Lumens

Lumens per watt efficiency demands your attention. IT DOES MATTER.

An LED fixture delivering 150 lumens/watt consumes significantly less energy than a product producing 100 lumens/watt for equivalent light output.

LED quality varies dramatically across manufacturers. Purchase based on required lumens, never on assumed wattage needs. Calculate lumens per watt by dividing total lumen output by power consumption. Both new fixtures and retrofit kits qualify for utility rebates when they meet DLC certification standards.

Verify DLC qualification on the DesignLights Consortium website before making your purchase decision.

DLC Premium products typically earn higher rebate amounts compared to DLC Standard fixtures. Your local utility company administers rebate programs and sets payment levels—check their website for current offerings. All DLC-qualified products include a minimum 5-year warranty. Our LED fixtures and retrofit lighting carry either UL Listed or ETL Listed certifications.

Installing retrofit units in existing fixtures maintains the original UL or ETL listing. Both certifications represent identical testing standards and safety requirements—only the certifying organization differs.

Expert Support That Saves You Money

Our lighting specialists deliver precise energy savings calculations based on your existing fixtures and operating schedules. We analyze your current utility rates and calculate exact monthly savings with specific LED replacements. For larger facilities, we provide complimentary custom lighting plans that optimize fixture placement and ensure proper light levels throughout your space. Our product specialists have designed lighting systems across every commercial application, from warehouses to manufacturing plants. This experience prevents costly mistakes like over-lighting areas or selecting fixtures that fail within warranty periods. You receive detailed specifications sheets showing actual photometric data, not marketing claims, so you make informed decisions backed by certified test results.