Support
BulbMatch — Light Bulb Color
Getting Started
How do I match a bulb?
Switch on a bulb in the fixture that still works, open BulbMatch, and point the rear camera at it. Hold the phone still until the reading settles, and the app gives you one of four answers — 2700K, 3000K, 4000K or 5000K — along with the phrases that bulb is sold under. Then save it to a room so you don't have to do it again.
What do 2700K, 3000K, 4000K and 5000K mean?
They are the four color temperatures nearly every household bulb in the US is sold in. 2700K is the yellowy glow of an old incandescent, 3000K is slightly whiter, 4000K is a neutral office white, and 5000K is a blue-white "daylight" bulb. Screw a 4000K bulb into a fixture full of 2700K bulbs and you will see the difference from across the room. BulbMatch's whole job is to tell you which of those four the fixture already has.
What is the white-paper method, and when should I use it?
Instead of aiming at the bulb itself, you hold a plain sheet of white paper under the bulb and aim at the paper. The app walks you through it. Reading light bounced off white paper is more reliable than reading a bulb head-on, because a lit bulb is a small, very bright source that the camera has to fight. Use it whenever the reading won't settle, whenever the app tells you it landed between two buckets, and any time the answer actually matters — like before you drive to the store.
Getting a Good Reading
Why does it say "Hold steady"?
BulbMatch samples continuously and only shows an answer once the reading stops moving. While the numbers are still wandering, the readout stays grayed and the app asks you to hold still. It would rather make you wait a second than hand you a number that was drifting when it froze.
It says the frame is too bright, or too dark. Now what?
Too bright usually means the bulb's hot spot is filling the frame — step back, or fill less of the frame with the bulb, or switch to the white-paper method. Too dark usually means you're too far from the light or the paper isn't catching enough of it — move in closer, or hold the paper directly under the bulb. BulbMatch can't read a bulb through a shade or a diffuser: take the shade off, or hold the paper under the fixture where only that bulb lights it.
Why do I have to point it at a bulb that still works?
BulbMatch reads the light coming out of a bulb. A dead bulb emits nothing, and the printing on the glass is usually burnt away or was never there. So use one of the survivors in the same fixture — in a three-bulb fitting, the two that still work tell you what to buy for the third. If every bulb in the fixture is dead, measure a fixture in the same room that you want to match instead.
Why should I turn the other lights off?
The camera reads whatever light reaches it. A window, a lamp on the other side of the room, or a ceiling fitting of a different temperature all mix into the reading and pull the answer toward the middle. Kill the competing light, leave the bulb you care about lit, and the reading settles faster and lands more cleanly.
It said "Between 2700K and 3000K". Which do I buy?
That message means the reading landed on the fence between two buckets, and the app won't pick for you on a coin flip. Do the white-paper reading with the other lights off — that usually breaks the tie. If it still won't commit, 2700K and 3000K are the closest pair on the scale, and buying the one that matches the phrasing on the bulbs already in the fixture is your best move.
What to Buy
Why does the app lead with the Kelvin number instead of the name?
Because the number is the half that everybody agrees on and the words are not. 2700K is 2700K on every box in the aisle. What that box calls it is up to the brand. So BulbMatch shows you the number first and then lists every phrase that bulb is sold under, and tells you plainly that the brands don't agree.
I've seen "soft white" on two bulbs that clearly don't match. How?
Because the packaging vocabulary is genuinely inconsistent in US retail. 2700K is usually sold as "Soft White" but sometimes as "Warm White". 3000K is sold as "Warm White", "Bright White" and "Soft White" depending on who made it. Two boxes can carry the same phrase and hold different bulbs. Match the Kelvin figure printed on the box — it's on every one of them, usually in small type near the lumens — and treat the words as a hint.
My fixture takes E12 or GU10, not a regular screw base. Does the app handle that?
Color temperature and base type are two separate things, and BulbMatch only reads the first. The base is a shape, not a light, so nothing about it shows up in the camera. You type it on the fixture — E26, E12, GU10, whatever it is — and the app stores it alongside the color so your shopping list carries both. If you're not sure of the base, take the dead bulb with you.
Rooms and Fixtures
How does saving a fixture work?
After a reading you tap Save to a room, name the fixture ("Living room ceiling", "Hallway sconces"), and set the bulb count and base type. It goes into a list grouped by room. Next time a bulb goes in that fitting, you open the app and read the answer off the list instead of measuring anything.
Can I re-measure a fixture I already saved?
Yes — open the fixture and tap Re-measure. Worth doing if you've since replaced every bulb in it, or if the original reading was a fence-sitter and you want to redo it on white paper. With the unlock, each fixture keeps its measurement history so you can see what it read before.
What is the shopping list?
It copies your fixtures out as text you can paste into Notes, Messages, or anything else — room, fixture, color temperature, base type, and how many bulbs. Handy when you're standing in the aisle, or when you're sending someone else to the store. The shopping-list copy is part of the unlock.
Why is a reading from my other iPhone flagged instead of just compared?
Different iPhone models have different camera sensors and filters, and they don't read a given bulb identically. BulbMatch records which device and which camera took every reading, so if a new reading on a fixture came from a different phone than the last one, it tells you rather than quietly stacking the two together as if they were the same measurement. If you're comparing readings, take them all on the same phone.
Free and Paid
What do I get for free?
3 measurements total — not three a day, three altogether — and 1 saved fixture. Those three readings are the full thing: the same four-bucket answer, the same packaging phrases, and the white-paper method included. Enough to fix one fixture and see whether the app is any use to you.
What does the unlock cost, and what does it add?
$4.99, paid once. It adds unlimited measurements, unlimited rooms and fixtures, calibration, measurement history on each fixture, and shopping-list copy. It's a non-consumable purchase and it's family shareable, so everyone in your Family Sharing group gets it.
How do I restore my purchase?
Open Settings inside the app and tap Restore Purchases. As long as you're signed in with the same Apple Account that bought it, the unlock comes straight back — on a new iPhone, after a reinstall, or on a second device. Nothing to re-buy and no receipt to dig up.
How do I cancel?
There's nothing to cancel. BulbMatch is not a subscription — there's no trial, nothing renews, and you will never be billed again after the one-time $4.99.
Calibration
What does calibration do?
You point the app at a bulb whose color temperature you already know — a new one, still in the box, with 2700K or 5000K printed on it — and tell BulbMatch what it should be reading. It stores the difference as an offset for that phone, and applies it to later readings. It's for the case where one phone reads consistently warm or consistently cool against a known bulb. Calibration is part of the unlock.
What can't calibration fix?
It corrects a steady bias; it cannot steady a reading that's jumping around. If the app can't get a reading to settle, calibrating won't change that — turn off the other lights and use the white-paper method instead. The offset is also stored per phone, because a correction worked out on one iPhone doesn't transfer to another.
Privacy
Where do my readings go?
Nowhere. They stay on your iPhone. BulbMatch has no account, no analytics and no network layer at all — put the phone in Airplane Mode and the app works exactly the same. No frame from the camera is ever saved, and nothing is ever written to your photo library. See the Privacy Policy for the full details.
What permissions does the app need?
Camera, and nothing else. The live preview is how the app reads the light. It never asks for your photo library, microphone or location, because it has no use for any of them.
Contact Us
Email Support
For questions, bug reports, or feature requests:
We typically respond within 48 hours. If a reading looks wrong, telling us your iPhone model, whether you used the white-paper method, and what the bulb's box says helps us a great deal.