Under-Cabinet Lighting Length Calculator

Enter your cabinet sections, section length, and light type to calculate total coverage length, fixture count, wattage, and estimated annual energy cost.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Enter Number of Cabinet Sections
Input how many individual cabinet runs require lighting. This helps calculate total length and fixture count.
2
Enter Section Length (in)
Specify the length of each individual cabinet section in inches. Ensure consistency for accurate results.
3
Select Light Type
Choose your preferred lighting type: LED Strip, Puck Lights, or Light Bar. Each has different coverage and wattage characteristics.
4
Review your results
The calculator provides the total lighting length, number of fixtures, estimated wattage, and projected annual running cost.

Example Calculation

A homeowner wants to install LED strip lighting under three 30-inch cabinet sections and needs to know the total length, wattage, and annual cost.

Number of Cabinet Sections

Section Length (in)

Light Type (select)

LED Strip

Results

90 in

Tips

Measure Each Section Individually

Always measure the exact length of each cabinet section. Cabinets aren't always uniform, and precise measurements prevent ordering too much or too little material.

Consider Light Spacing for Puck Lights

For puck lights, optimal spacing is typically 12-18 inches apart to ensure even illumination without creating distracting hot spots or dark areas on the countertop.

Evaluate Dimmer Compatibility

If you plan to use a dimmer, ensure that both your chosen light fixtures and the associated transformer/driver are compatible with dimming technology. Not all LED products are dimmable.

Designing Your Kitchen Glow: Calculating Under-Cabinet Lighting Length and Cost

This Under-Cabinet Lighting Length Calculator provides key metrics for planning your kitchen illumination, from total linear length to the number of fixtures, estimated wattage, and projected annual running cost. By considering your cabinet sections and chosen light type, you can make informed decisions to create a functional and aesthetically pleasing environment in your home in 2025. This tool helps ensure you buy the right amount of material and understand the long-term operational expenses.

The Practicality of Precise Lighting Planning

Precise planning for under-cabinet lighting is essential for both functional and financial reasons. Incorrect length calculations can lead to uneven lighting, dark spots, or unnecessary material waste. Similarly, underestimating wattage can result in insufficient illumination, while overestimating can lead to higher upfront costs and energy consumption. By accurately determining these factors, homeowners can ensure their kitchen countertops are perfectly lit for tasks, optimize energy usage, and avoid costly installation errors or subsequent replacements.

The Logic for Calculating Under-Cabinet Lighting Parameters

The calculation dynamically adjusts based on the chosen light type, as each has a distinct method for determining fixture count, wattage, and coverage.

Calculate Total Length: Total Length (in) = Number of Cabinet Sections × Section Length (in) Total Length (ft) = Total Length (in) / 12
Determine Fixtures & Wattage by Type:
- LED Strip: Fixtures = Number of Cabinet Sections Wattage = Total Length (ft) × 4 W/ft
- Puck Lights: Fixtures = CEIL(Total Length (in) / 12 in spacing) Wattage = Fixtures × 3 W/unit
- Light Bar: Coverage (in) = Total Length (in) × (2/3) Fixtures = CEIL(Coverage (in) / Section Length (in)) Wattage = Fixtures × 8 W/unit
Calculate Annual Cost: Annual kWh = (Wattage / 1000) × Daily Usage Hours (e.g., 8) × 365 days Annual Cost = Annual kWh × Cost Per kWh (e.g., $0.13)

This logic provides a comprehensive overview of your lighting needs.

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Choosing the Right Fixture Type for Under-Cabinet Illumination

Selecting the appropriate under-cabinet lighting fixture is crucial for achieving the desired aesthetic and functionality. LED strips are favored for their seamless, continuous light output, ideal for comprehensive task lighting and minimizing shadows. They typically consume a low wattage (around 4-6 W/ft) and offer a wide range of color temperatures, from warm 2700K to cool 4000K, allowing for versatile ambiance control. Puck lights provide distinct, focused pools of light, best suited for accentuating specific items or creating a decorative effect. Light bars offer a more directional and often brighter illumination, excellent for areas needing intense task lighting over a segment of the counter. Each type caters to different design preferences and lighting needs, impacting both the visual result and the overall energy footprint.

Recommended Lighting Levels for Kitchen Countertops

For comfortable and safe food preparation, kitchen countertops require specific lighting levels, typically measured in foot-candles (fc) or lux. Industry benchmarks suggest that 30-50 foot-candles (approximately 300-500 lux) is the optimal range for task lighting on kitchen work surfaces. This ensures sufficient brightness to see clearly, minimize eye strain, and perform detailed activities like chopping or reading recipes without shadows. Achieving this level often requires a combination of general ambient lighting and targeted under-cabinet fixtures. For example, a continuous LED strip emitting 200-300 lumens per foot can effectively deliver these recommended foot-candle levels across the countertop, providing both functional and aesthetic illumination.

Calculating Under-Cabinet Lighting for Three 30-Inch Sections

Let's calculate the lighting parameters for three 30-inch cabinet sections using LED strip lighting:

Number of Cabinet Sections: 3
Section Length: 30 inches
Light Type: LED Strip

First, calculate the total length in inches: 3 sections × 30 inches/section = 90 inches. Convert to feet: 90 inches / 12 inches/foot = 7.5 feet. For LED strips, the number of fixtures (or runs) is typically one per section: 3 fixtures. Estimated wattage (assuming 4 W/ft for LED strips): 7.5 ft × 4 W/ft = 30 W. Watts per foot: 30 W / 7.5 ft = 4 W/ft. Estimated annual cost (assuming 8 hours/day usage and $0.13/kWh): Annual kWh = (30 W / 1000) × 8 hrs/day × 365 days/year = 87.6 kWh Annual Cost = 87.6 kWh × $0.13/kWh = $11.39.

So, for this setup, you'll need 90 inches (7.5 ft) of LED strip, 3 separate runs, consuming 30 W, with an estimated annual cost of $11.39.

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Frequently Asked Questions

How do LED strips, puck lights, and light bars differ for under-cabinet use?

LED strips provide continuous, even illumination, ideal for task lighting. Puck lights offer focused, accent lighting, creating distinct pools of light. Light bars are typically rigid fixtures that provide directional, often brighter, illumination over a specific area. Each type suits different aesthetic and functional preferences for under-cabinet applications.

What is a good wattage per foot for under-cabinet lighting?

A good wattage per foot for under-cabinet lighting typically ranges from 3-6 watts per foot (W/ft) for LED strips, providing ample task lighting. For puck lights, it's usually 2-4 watts per puck. This low wattage ensures energy efficiency while delivering sufficient brightness for kitchen countertops without being overly harsh.

How is the annual running cost of under-cabinet lighting calculated?

The annual running cost of under-cabinet lighting is calculated by multiplying the total estimated wattage by the average daily usage hours (e.g., 8 hours), then by 365 days, and finally by the local electricity cost per kilowatt-hour (kWh). The wattage is divided by 1000 to convert to kilowatts before multiplying by the cost per kWh.

Should under-cabinet lighting cover the full length of the cabinet?

For optimal task lighting and even illumination, under-cabinet lighting, especially LED strips, should ideally cover the full length of the cabinet sections. This minimizes shadows and ensures consistent light across the entire countertop workspace. For accent lighting or smaller areas, partial coverage with puck lights or shorter light bars might be acceptable.