# Recessed Lighting Calculator

Calculate how many recessed lights you need for any room. Enter room dimensions, pick your brightness level, and get the count plus spacing layout.

## What this calculates

Planning a recessed lighting layout? Enter your room dimensions and desired brightness, and this calculator tells you exactly how many lights to install and how far apart to space them. No more guessing whether your room will be too dim or too bright.

## Inputs

- **Room Length** (ft) — min 1, max 200
- **Room Width** (ft) — min 1, max 200
- **Desired Foot-Candles** — options: 20 FC - Hallway / Ambient, 30 FC - Living Room / Bedroom, 40 FC - Kitchen / Dining, 50 FC - Office / Workshop, 70 FC - Task / Detail Work — Higher foot-candles = brighter room
- **Lumens per Light** — options: 450 lm - 4" trim (40W equiv), 650 lm - 4" trim (60W equiv), 800 lm - 6" trim (60W equiv), 1100 lm - 6" trim (75W equiv), 1600 lm - 6" trim (100W equiv) — Check the lumen rating on the bulb or fixture packaging

## Outputs

- **Room Area**
- **Total Lumens Needed**
- **Lights Needed**
- **Recommended Spacing**
- **Distance from Walls**

## Details

The core formula is:

Number of lights = (Room sq ft x Foot-candles) / Lumens per light

Recommended Foot-Candle Levels

  Room TypeFoot-Candles
  Hallways, Stairs15-20
  Living Room, Bedroom20-30
  Kitchen (general)30-40
  Kitchen (task areas)50-70
  Office, Workshop50-70
  Bathroom40-50

Spacing Guidelines

  - General rule: Space lights evenly in a grid pattern

  - Wall offset: Place the first row at half the spacing distance from the wall

  - 4" fixtures: Better for focused task lighting, closer spacing

  - 6" fixtures: Better for general illumination, wider spread

For example, a 15x12 ft kitchen (180 sq ft) at 40 foot-candles with 800-lumen lights needs 9 lights spaced about 4.5 feet apart, with the first row about 2.2 feet from the wall.

## Frequently Asked Questions

**Q: How far apart should recessed lights be?**

A: The general rule is to divide the ceiling height by 2 to get maximum spacing. For 8-foot ceilings, that's 4 feet apart. For 10-foot ceilings, 5 feet. This calculator gives you optimal spacing based on your specific room size and light count.

**Q: Should I use 4-inch or 6-inch recessed lights?**

A: 6-inch is the most popular for general room lighting because it provides broader, more even illumination. 4-inch works better for accent lighting, task lighting over counters, or in smaller spaces like bathrooms. You can mix sizes in the same room.

**Q: How far should recessed lights be from the wall?**

A: Place recessed lights about half the spacing distance from the wall, typically 2-3 feet. If you want to wash the walls with light (wall washing), position them 2-3 feet from the wall and aim them outward.

**Q: What color temperature should I choose?**

A: For homes, 2700K (warm white) is cozy for living rooms and bedrooms. 3000K (soft white) works well for kitchens and bathrooms. 4000K (neutral) is good for offices and task areas. Avoid mixing different color temperatures in the same room.

**Q: Do I need an electrician to install recessed lighting?**

A: For new construction or adding wiring, yes, hire a licensed electrician. Replacing existing recessed fixtures with new ones is a simpler DIY project. If you're adding lights where none existed, the wiring and potential ceiling joist work typically requires professional installation.

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Source: https://vastcalc.com/calculators/everyday/recessed-lighting
Category: Everyday Life
Last updated: 2026-04-08