BulbBrief
Free room light-bulb calculator

Stop guessing at the bulb aisle.

Tell us about the room. BulbBrief turns its size, purpose, fixtures, and atmosphere into one exact light-bulb specification — the lumens, color temperature, CRI, shape, and base to buy.

Get my bulb spec The bulb box, decoded
✓ No accounts, no cookies ✓ Instant, in your browser ✓ Shop by lumens, not watts

“Buy an A19 LED with an E26 base, about 800 lm, 2700K, 90+ CRI.”

One sentence.Zero guesswork.

Light bulb calculator

Answer a few quick questions about the room. Fields marked * are required; the rest are optional and sharpen the result.

1 Your room
Room size
2 Your fixtures
Light-producing fixtures in the room.
Not sure? Look at the old bulb or the label inside the fixture.
3 How you want it to feel
More detail (optional, sharpens the result)
Adds a separate task-light tip — it won’t over-brighten the room.
Free · instant · stays on your device

What “warm” and “cool” light actually look like

Color temperature is measured in Kelvin (K). Lower numbers look warm and golden; higher numbers look cool and bluish. It describes the look of the light — not heat, and not brightness.

One clear answer, not a physics lesson

Most lighting calculators bury you in lux, foot-candles, and coefficients. BulbBrief does that math behind the scenes and hands you a single shopping sentence.

Brightness, decoded

We give you the lumens to look for and the familiar “60-watt-equivalent” it maps to — so you stop shopping by watts.

The right white

A warm-to-cool Kelvin target so the room feels the way you want — cozy bedroom, crisp kitchen, flattering bathroom.

Fits your socket

Shape and base guidance — A19/E26, BR30, GU10, B11/E12 — plus CRI and dimming, so the bulb physically fits and looks right.

The bulb box, decoded.

Bulb packages contain several numbers, but each one answers a different question. BulbBrief translates all of them into one specification you can take to the store.

  • 800 lm How bright is it?

    Lumens measure brightness. 800 lm ≈ an old 60-watt bulb. Shop by lumens, not watts.
  • 2700K How warm is the white?

    Kelvin is the color of the light. 2700K is warm and cozy; 5000K is cool daylight.
  • 90+ CRI Will colors look natural?

    CRI rates color accuracy out of 100. 90+ keeps skin, food, and fabrics true.
  • A19 What shape is it?

    A19 is the classic household bulb shape. Others: BR30 (cans), B11 (chandelier), GU10 (spot).
  • E26 Will it fit my socket?

    The base/socket size. E26 is the standard screw base; E12 is the smaller candelabra.
  • Dimmable Will it work on my dimmer?

    Only “dimmable” bulbs dim without buzz or flicker — and only on a compatible dimmer.
BulbBrief turns all six into one →

“A dimmable A19 LED, E26 base, ~800 lm, 2700K, 90+ CRI.”

Decode my room

Popular room & color guides

Prefer to read first? These plain-English guides answer the most common bulb questions. Browse all guides →

Bedroom bulbs
Warm, restful light that still works for reading.
Bathroom bulbs
Flattering, accurate light for grooming and makeup.
Kitchen bulbs
Bright, clean light for cooking and prep.
Living-room bulbs
Layered, inviting light for everyday and evenings.
2700K vs. 3000K
Which warm white should you actually pick?
Soft white vs. daylight
Decode the confusing labels on the box.

Avoid the wrong bulb

The six mistakes that send people back to the store. BulbBrief’s recommendation steers you clear of every one.

Buying by watts

“60 watts” describes an old incandescent. LED watts are far lower and vary by product.

Fix: shop by lumens (brightness).

Wrong base or shape

An E12 bulb won’t screw into an E26 socket, and a BR30 won’t seat like an A19.

Fix: match the shape and base exactly.

Light too cool

5000K “daylight” bulbs feel clinical in a bedroom or living room.

Fix: use the Kelvin target for the room.

Ignoring CRI

Low-CRI bulbs make skin, food, and clothing colors look dull or wrong.

Fix: 90+ CRI (95+ for makeup).

Non-dimmable on a dimmer

A non-dimmable LED on a dimmer buzzes, flickers, or won’t dim at all.

Fix: buy “dimmable” + a compatible dimmer.

Wrong damp/wet rating

Standard bulbs fail early in showers, bathrooms, and covered outdoor spots.

Fix: use damp- or wet-rated where required.