Soft white vs daylight bathroom bulbs

What the numbers mean

Kelvin is color temperature, not brightness. 2700K is the warm yellow-white of a traditional incandescent; 5000K is a neutral white with more blue in it. Nothing about Kelvin changes how much light you get.

Lumens is brightness, and both of these publish 500. CRI is color accuracy on a 100-point scale, and both publish 90. The full bulb ranking is here.

Because the two bulbs are identical on every specification except Kelvin, this is one of the few comparisons on this site with a single variable in it.

Where daylight wins

• Makeup. Color matched under 2700K light drifts warm; under 5000K it is closer to what daylight will show.
• Shaving. Cooler light picks out contrast and shadow better on skin.
• A windowless bathroom. With no daylight coming in, the bulb is the only reference the room has. Lighting a windowless bathroom is covered here.

Where soft white wins

• Continuity with the rest of the house. Most homes are lit at 2700K, and a 5000K bathroom announces itself from the hallway.
• Evening use. Warm light at night is easier on the eyes than a cool one.
• A bath rather than a shower. Nobody wants to soak under 5000K.

The answer most people should actually use

Put the cooler bulb where the task is and the warmer bulb where it is not, or fit a dimmer. Both of these are published as dimmable with a dimmer switch, and dimming a 5000K bulb takes the edge off without changing its color. If your fixture holds more than one bulb, do not mix Kelvin values in the same fitting — it looks like one bulb has failed.

Check the base and the shape first

Both are G25 globes on a medium base. That is the bulb a great many vanity fixtures take, but not all: Kohler’s Simplice bar, for instance, publishes candelabra E12 sockets with “type B10 or T10 bulbs recommended”, which these will not fit. Check the socket before the color. Fixture sizing is here.

CRI is doing more work than Kelvin

Color temperature decides whether light looks warm or cool. Color rendering decides whether the colors it lands on look like themselves. Both of these publish CRI 90, which is why the choice between them is genuinely a preference rather than a quality question.

It is worth knowing because the cheapest bulbs in any supermarket are 2700K at CRI 80, and people conclude from those that warm light is unflattering. It is not the Kelvin doing that; it is the ten points of color rendering. The mirrors that publish even higher CRI are here.

Dimming, and the switch you may not have

Both bulbs publish dimming as “Yes with Dimmer Switch” — which is a conditional, not a feature. A dimmable bulb on a standard on/off switch simply runs at full output, and fitting a dimmer is a wiring job rather than a bulb swap.

If you want one light that works for makeup in the morning and a bath at night, that dimmer is the piece that makes it possible, and it is worth budgeting for alongside the bulbs rather than discovering later.

What they cost to run

At 5.5 W, three hours a day and 18.34 cents per kWh: 5.5 × 3 × 365 ÷ 1000 × $0.1834 = about $1.10 a year per bulb. There is no running-cost argument between them, because they draw the same power.

If you rent

A bulb swap is the most reversible upgrade in the bathroom: both rate Safe, and the landlord’s bulbs go back in a drawer until you leave. The other no-permission mirror upgrades are here.