# How Many Lumens Does a Room Need? Lighting by the Numbers

> Lumens per room, the right Kelvin for every space, CRI, recessed-light spacing and hanging heights — the lighting numbers, in one table-heavy guide.

- Canonical: https://roomredesign.co/en/blog/lighting-lumens-kelvin-guide/
- Published: 2026-09-05 · Language: en
Lighting is the cheapest thing in a room and the one that decides whether the rest of it works. It is also the only part of interior design with a full set of published numbers — and almost nobody uses them.

Here is the whole specification: how much light, what colour, how good, and where to put it.

## Step 1: how much light (lumens)

Brightness is measured two ways. **Lumens** are what a bulb emits. **Lux** is what lands on a surface — one lux is one lumen per square metre. Rooms are specified in lux, bulbs are sold in lumens, and the conversion is simply:

> **Total lumens needed = room area in m² × target lux**

| Room | Target lux | 10 m² | 15 m² | 20 m² | 30 m² |
|---|---|---|---|---|---|
| Living room (general) | 100–150 | 1,000–1,500 | 1,500–2,250 | 2,000–3,000 | 3,000–4,500 |
| Living room (reading corner) | 300 at the book | — | — | — | — |
| Bedroom (general) | 100–150 | 1,000–1,500 | 1,500–2,250 | 2,000–3,000 | — |
| Kitchen (general) | 200–300 | 2,000–3,000 | 3,000–4,500 | 4,000–6,000 | — |
| Kitchen (counter task) | 400–500 at the counter | — | — | — | — |
| Bathroom (general) | 200–300 | 2,000–3,000 | — | — | — |
| Bathroom (mirror) | 500 at the face | — | — | — | — |
| Home office | 300–500 | 3,000–5,000 | 4,500–7,500 | 6,000–10,000 | — |
| Dining room | 150–200 | 1,500–2,000 | 2,250–3,000 | 3,000–4,000 | — |
| Hallway / stairs | 100–150 | 1,000–1,500 | — | — | — |
| Laundry / garage / workshop | 300–500 | 3,000–5,000 | — | — | — |

Two corrections to apply after the arithmetic:

- **Dark walls eat light.** A room in a deep charcoal or forest green reflects roughly half of what a white room does. Add 30–50% to the total.
- **High ceilings lose light.** Illuminance falls with the square of distance. Above 280 cm, add about 20%.

Since watts no longer track brightness, this is the conversion table worth keeping:

| Old incandescent | Lumens | Typical LED watts |
|---|---|---|
| 25 W | 250 lm | 3 W |
| 40 W | 450 lm | 5 W |
| 60 W | 800 lm | 8 W |
| 75 W | 1,100 lm | 11 W |
| 100 W | 1,600 lm | 15 W |
| 150 W | 2,600 lm | 22 W |

## Step 2: what colour (Kelvin)

Colour temperature is the single biggest driver of how a room *feels*, and the easiest thing to get wrong in a supermarket aisle.

| Kelvin | Name | Looks like | Use it in |
|---|---|---|---|
| 2,200K | Amber / candle | Sunset, firelight | Accent lamps, bedside, restaurant-style dimming |
| 2,700K | Warm white | Old incandescent | Living rooms, bedrooms, dining rooms — the default |
| 3,000K | Soft white | Slightly crisper warm | Bathrooms, kitchens, hallways |
| 3,500K | Neutral | Neither warm nor cool | Kitchen task lighting, utility |
| 4,000K | Cool white | Overcast daylight | Garage, laundry, workshop, a make-up mirror if you prefer accuracy over flattery |
| 5,000K+ | Daylight | Office ceiling | Nowhere in a home you want to relax |

Three rules that prevent the majority of lighting complaints:

1. **Do not mix temperatures within sight of each other.** A 2,700K lamp beside a 4,000K downlight makes the warm one look yellow and dirty. Pick one per room, and one per open-plan sightline.
2. **Match the light to the paint.** Warm whites, beiges and terracottas need 2,700K; a cool grey or a blue-green survives 3,000K. If a "greige" wall has gone green on you, the bulb is a likelier culprit than the paint — see [most popular paint colours](/en/blog/most-popular-paint-colors) for how these shades behave.
3. **Warmer as it gets later.** Fittings that dim to warm (2,700K down to 2,200K) mimic sunset and are worth the premium in a bedroom or living room.

## Step 3: how good (CRI and R9)

CRI scores colour accuracy against daylight out of 100. It is printed on the box and routinely ignored.

| CRI | Verdict |
|---|---|
| Below 80 | Avoid. Reds go brown, skin goes grey, wood loses its grain |
| 80–89 | Acceptable in a corridor or a garage |
| 90–95 | Correct for living spaces — buy this |
| 95+ | Bathrooms, dressing areas, art walls, anywhere colour is judged |

If a spec sheet lists **R9**, look at it. R9 is the deep-red score, it is the value manufacturers cut to hit a headline CRI number, and it is why some "CRI 90" bulbs still make a red sofa look dull. R9 above 50 is good.

## Step 4: where to put it (three layers)

A room needs at least three light sources at different heights. This is the layer that fixes rooms that "just don't feel cosy" no matter what furniture goes in them.

| Layer | Job | Typical fittings | Height |
|---|---|---|---|
| Ambient | Fills the room, lets you move safely | Ceiling fitting, uplighter, cove | Ceiling |
| Task | Enough light on the thing you are doing | Reading lamp, under-cabinet strip, desk lamp | 40–120 cm |
| Accent | Depth, shadow, focus | Picture light, spot on a plant, table lamp | Varies |

A useful shorthand: **at least three sources, at three different heights, on at least two switches.** The moment a room has a floor lamp, a table lamp and something on the ceiling — all dimmable — it stops looking like a rental.

For where those pools of light should fall in each room, [lighting ideas for every room](/en/blog/lighting-ideas-for-every-room) walks it space by space.

## Placement and hanging heights

| Fitting | Number |
|---|---|
| Recessed spacing | Ceiling height ÷ 2 (120 cm apart on a 240 cm ceiling) |
| Recessed distance from walls | 60–90 cm |
| Recessed over a counter | 50–60 cm out from the wall |
| Pendant over a dining table | 75–90 cm above the tabletop |
| Pendant over an island | 75–85 cm above the counter, 60–75 cm between centres |
| Chandelier in a stairwell / double height | Bottom at least 210 cm above any floor |
| Wall sconce, general | 150–165 cm from the floor |
| Bathroom vanity sconces | 165 cm high, 90 cm apart, flanking the mirror |
| Bedside reading lamp | Shade bottom at 100–120 cm, roughly shoulder height sitting up |
| Floor lamp beside a sofa | Shade bottom at seated eye level, 105–120 cm |
| Under-cabinet strip | 200–300 lm per 30 cm of run, mounted at the front edge |
| Picture light | Centred, 15–20 cm above the frame |

Two placement notes that matter more than they sound:

- **Vanity light goes beside the mirror, not above it.** A downlight above a mirror casts shadows into the eye sockets and under the chin, which is why bathroom selfies look terrible under it. Two sconces at face height light the face evenly.
- **Do not centre a downlight over the front of a counter.** Put it between you and the wall, or your own shoulders shade the chopping board.

## Dimming, and why half of it fails

Most "the dimmer buzzes / flickers / stops at 40%" complaints come from mismatched hardware, not faulty bulbs.

- Use a **trailing-edge (LED-compatible) dimmer**. Old leading-edge dimmers were designed for filament loads.
- Respect the dimmer's **minimum load**. A dimmer rated 10–200 W will misbehave with three 5 W bulbs on it.
- Keep **all bulbs on one circuit identical** — same brand, same model. Mixed drivers dim at different rates and you get a staircase instead of a fade.
- Check the bulb actually says **dimmable**. A non-dimmable LED on a dimmer flickers and dies early.

## Colour temperature and paint: the interaction nobody warns you about

The same wall colour reads differently under every one of the temperatures above, and the effect is not subtle: a warm white paint under 4,000K light turns grey and clinical, while a cool grey under 2,700K turns beige-purple.

The order that saves repainting: choose the lighting first, or at least choose it at the same time, and judge every paint sample **under the bulbs the room will actually have, at night**. A daylight test tells you nothing about the eleven hours you use the room.

If you want to see the interaction before buying either, [Architectural AI](/en/download) can relight a photo of your real room — warmer, cooler, brighter — and repaint the walls in the same pass, so the paint-and-bulb pairing is a picture rather than a guess. There is a walkthrough in [test paint colours on a photo of your wall](/en/blog/test-paint-colors-on-a-photo-of-your-wall).

## A worked example: a 22 m² living room

1. **Total light.** 22 m² × 150 lux = 3,300 lumens. Walls are a mid-green, so add 40%: about 4,600 lumens.
2. **Split it.** A 1,600 lm pendant on a dimmer, two 800 lm table lamps, one 800 lm floor lamp beside the reading chair, and 600 lm of accent — a picture light and a spot on the plant.
3. **Colour.** Everything at 2,700K, CRI 90+.
4. **Control.** Ceiling on one dimmer, lamps on a second switched circuit. Evening setting: ceiling at 20%, lamps full.
5. **Task check.** The reading chair needs 300 lux at the book — an 800 lm lamp at 60 cm delivers it.

That is a properly lit room, and it is about six purchases. For the wider decisions the lighting sits inside, see [how interior design affects your mood](/en/blog/how-interior-design-affects-your-mood) and [calming bedroom ideas for better sleep](/en/blog/calming-bedroom-ideas-better-sleep).

## Frequently asked questions

### How many lumens do I need for a living room?

Aim for 100–200 lux, which for a 20 m² living room means roughly 2,000–4,000 lumens in total. Split that across at least three fittings rather than one — for example a 1,200 lumen pendant, two 800 lumen table lamps and a 400 lumen accent light. A single 3,000 lumen ceiling light technically meets the number and still lights the room badly, because all of it arrives from one direction.

### What is the difference between lumens and watts?

Lumens measure light output; watts measure power draw. With LEDs the two have decoupled, so watts tell you almost nothing about brightness. The equivalents worth memorising: 450 lumens replaces an old 40 W bulb, 800 lumens replaces 60 W, 1,100 lumens replaces 75 W and 1,600 lumens replaces 100 W. A modern LED delivers 800 lumens on about 8 W.

### What colour temperature should I use at home?

Use 2,700K for living rooms, bedrooms and dining rooms; 3,000K for bathrooms and general kitchen light; 3,500–4,000K only over kitchen work surfaces, in a laundry or in a garage. Avoid 5,000K and above anywhere you relax — it is daylight-white, it reads as an office, and it suppresses the warm end of every paint colour and wood tone in the room.

### What is CRI and does it matter?

CRI (Colour Rendering Index) scores how accurately a light source shows colour against daylight, out of 100. Below CRI 80, reds and skin tones go flat and grey-beige walls turn muddy. Buy CRI 90 or better for living spaces and CRI 95 for a bathroom mirror, an art wall or anywhere you get dressed. It is printed on the box and it is the specification most people never check.

### How far apart should recessed lights be?

Divide the ceiling height by two and use that as the spacing: 120 cm apart on a 240 cm ceiling, 135 cm on a 270 cm ceiling. Keep the first row 60–90 cm from the walls so the light washes down the wall rather than cutting a scallop into it. Over a work surface, place them 50–60 cm out from the wall so your body does not shadow the counter.

### How high should a pendant hang over a table or island?

Hang the bottom of the shade 75–90 cm (30–36 in) above a dining table and 75–85 cm above a kitchen island. Over a table, the fitting should be about half to two-thirds the table width; over an island, use two or three pendants spaced evenly with 60–75 cm between centres. In a room with a ceiling above 270 cm, add 8 cm of drop for every extra 30 cm of height.