How to Choose LED Bulbs for Different Rooms

Walk into any lighting aisle and you will meet a wall of boxes covered in numbers: kelvins, lumens, watts, beam angles, cap types. It can feel as though buying a light bulb now requires a certificate in physics. In truth, three of those numbers do almost all the work, and once you understand them you can light a whole house confidently, room by room, without guessing.

Colour temperature: the warmth of the light

Colour temperature is measured in kelvin (K) and describes how warm or cool the light looks, not how bright it is. Lower numbers are warmer and more yellow; higher numbers are cooler and bluer. This single choice has more effect on how a room feels than almost anything else.

• 2200K–2400K: a deep, candle-like amber. Lovely for a bedside lamp or a cosy corner, less useful as general light.
• 2700K: classic warm white, close to the old incandescent glow. The safe default for living rooms, bedrooms, hallways and dining areas.
• 3000K: warm but slightly crisper. Excellent in kitchens and bathrooms where you want warmth without a yellow cast.
• 4000K: cool white. Clean and alert, well suited to utility rooms, garages, studies and under-cabinet task lighting.
• 5000K–6500K: daylight. Useful in a workshop or over a workbench, but harsh in a space where you relax.

A common mistake is mixing temperatures on the same circuit — a 4000K bulb beside a 2700K one makes both look wrong. Keep every bulb in a single room within a narrow band, ideally 2700K to 3000K downstairs and 2700K in bedrooms.

Brightness: think lumens, not watts

Watts measure power consumption; lumens measure light output. With LEDs, a 9W bulb often produces the same light as an old 60W incandescent, so shopping by wattage alone will leave you disappointed.

As a rough guide, multiply the old wattage you were used to by about thirteen. A 40W equivalent is around 470 lumens, a 60W equivalent around 800 lumens, and a 100W equivalent around 1500 lumens. Modern LEDs typically deliver 90 to 120 lumens per watt, so a good quality 10W bulb should comfortably exceed 900 lumens.

Also consider the total light in a room rather than a single bulb. A kitchen may need 400 to 500 lumens per square metre spread across ceiling and task fittings, while a bedroom is comfortable at around 150 to 200 lumens per square metre with lamps to top it up. If a room has dark walls or a low ceiling, add a little extra.

Beam angle: where the light actually lands

Beam angle describes how widely the light spreads. A narrow beam punches a bright pool onto one spot; a wide beam washes the room evenly.

• 15°–25°: a tight spotlight for artwork, a chimney breast or a display shelf.
• 36°–40°: the classic GU10 spot, ideal for downlights over a kitchen worktop or a bathroom mirror.
• 60°: a balanced flood, good for general downlighting in halls and landings.
• 100°–120°: wide and soft, best for ceiling pendants and lampshades where you want ambient light.

If you are replacing existing downlights, keep the same beam angle unless you are deliberately changing the effect, or the room will suddenly feel either spotty or flat.

The room-by-room guide

• Living room: 2700K, 800 lumens in the main pendant, with 400-lumen lamps on side tables. Choose a wide beam for the ceiling and something narrower over a reading chair.
• Kitchen: 3000K, 4000K under wall cabinets for prep work. Downlights over the worktop at 36°, general ceiling light around 800 to 1100 lumens.
• Bedroom: 2700K throughout, dimmable, with 2200K bedside lamps if you like a wind-down glow. Avoid cool white here at all costs.
• Bathroom: 3000K–4000K over the mirror for accurate shaving and make-up, 2700K elsewhere. Fittings in zones near water need an appropriate IP rating, usually IP44 or higher.
• Hallway and stairs: 2700K–3000K at 60° beam, bright enough to feel safe at around 600 to 900 lumens, ideally on a sensor or two-way switch.
• Home office: 4000K, 90+ CRI, with a desk lamp angled to avoid glare on the screen.

Dimming, fittings and final checks

Check the cap type before you buy — E27, E14, B22, GU10, G9 and MR16 are all common in UK homes, and they are not interchangeable without changing the fitting. If you want to dim, look for bulbs explicitly marked as dimmable, and match them to a compatible LED dimmer; older dimmer switches often cause flicker, buzzing or a narrow dimming range. A dimmer rated for LEDs, or a trailing-edge dimmer, solves most of it.

Two last details are worth the seconds they take. Look for a colour rendering index (CRI) of 80 or above, and 90 or above in kitchens, bathrooms and anywhere you dress or apply make-up, so colours look true. And buy your bulbs for a room at the same time and from the same range, because two batches of "warm white" can differ just enough to notice once they are side by side in the ceiling.