Interior Lighting Design Calculator
A Kitchen Needs Roughly Double a Bedroom's Light
General lighting requirements vary sharply by room function — task-heavy spaces like kitchens and bathrooms call for far more illumination than a bedroom meant for relaxing. This calculator starts from the room type, applies a recommended foot-candle target for that specific use, and converts it into a total lumen figure to plan fixtures against, rather than treating every room the same.
The Formula
The recommended foot-candle level is drawn from commonly cited general-lighting guidelines by room type — ranging from about 10 foot-candles for a hallway up to 50 for a garage workspace.
Where This Calculation Matters
- Selecting the right number of fixtures — dividing the total lumens needed by a single fixture's rated output tells you how many fixtures to plan for.
- Comparing bulb technologies — LED, halogen, and incandescent bulbs of the same wattage output very different lumens, so working from a lumen target rather than a wattage habit avoids under- or over-lighting a room.
- Kitchen and bathroom task lighting — these rooms carry the highest recommended foot-candle levels in the table below, reflecting the detailed visual tasks performed in them.
- Whole-home lighting plans — running each room through the same formula with its own foot-candle target builds a consistent, room-appropriate lighting budget for an entire house.
Recommended Lighting by Room Type
For a 12 ft × 15 ft (180 sq ft) room:
| Room type | Foot-candles | Total lumens |
|---|---|---|
| Hallway | 10 | 18,000 |
| Living room / Bedroom | 15 | 27,000 |
| Closet | 20 | 36,000 |
| Dining room | 30 | 54,000 |
| Kitchen | 35 | 63,000 |
| Bathroom / Home office | 40 | 72,000 |
| Garage | 50 | 90,000 |
These are general planning estimates for overall room lumen budgets; actual fixture placement should also account for ceiling height, surface reflectance, and dedicated task lighting.
How to Use This Calculator
- Select your Room Type from the dropdown.
- Enter Room Length and Room Width (ft).
- Select Calculate to see the total lumens recommended for that room's general lighting.
Related Calculations
Need a custom foot-candle target instead of a preset room type? Use the Lumen Requirement Calculator, or plan the room's furniture layout with the Interior Design Space Planner.