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A dimming curve determines how a dimmer adjusts the light intensity as you move the control from the highest setting to the lowest. It is the translation of a physical action into a perceived change in light. A well-calibrated dimming curve ensures that the light dims smoothly and naturally, without jumps, flickering, or sudden outages. Especially with LED lighting, choosing the right dimming curve makes a big difference in everyday comfort. In this article, we answer the most frequently asked questions about dimming curves, from the basics to practical setup tips.
How does a dimming curve work in practice?
A dimming curve is a graphical representation of the relationship between the position of the dimmer switch and the actual light output. When you set the dimmer to 50%, the dimming curve determines whether the light actually shines at 50% of its maximum brightness, or at a higher or lower level. The curve is therefore the link between your action and the result you see.
In practice, a dimmer works by modulating the voltage or current to the light bulb. With LED dimmers, this is often done via PWM (pulse width modulation), in which the current is rapidly switched on and off. The ratio between on and off time determines the brightness. The dimming curve defines how that ratio changes as you move the control. A well-designed dimming curve feels intuitive: a small adjustment at the beginning produces a noticeable change, but halfway through the scale, the lamp responds more smoothly and controllably.
What is the difference between a linear and a logarithmic dim curve?
A linear dimming curve adjusts the light output in equal increments across the entire control range. A logarithmic dimming curve adjusts the output based on how the human eye perceives light, making the dimming appear uniform across the entire range. For most living spaces, a logarithmic curve is the better choice.
The human eye is more sensitive to changes in low light levels than in high ones. With a linear curve, the first 20% of the dimming range already feels like a significant jump, while the rest of the scale seems to make little difference. A logarithmic curve compensates for this by taking smaller steps in the lower range and larger steps higher up the scale. The result is a dimming experience that feels consistent across the entire scale.
- Linear dimming curve: equal electrical steps, but visually uneven
- Logarithmic dimming curve: adapted to human light perception, visually smooth
- S-curve: a setting that responds more gently at both the beginning and the end of the control range
Why do my lights flicker or jump when I dim them?
Flickering or stuttering when dimming is usually caused by a mismatch between the dimmer and the LED bulb, an incorrectly set dimming curve, or a minimum setting that is too low, causing the bulb to fall just below its operating threshold. This is one of the most common complaints among people who dim lights using a dimmer that is not specifically designed for LEDs.
Traditional dimmers were designed for incandescent bulbs, which behave very differently from LED bulbs when it comes to electrical characteristics. LED drivers are more sensitive to voltage fluctuations and can become unstable at certain dimming levels. This manifests as visible flickering, sudden failure at low dimming levels, or the sensation that the light is jumping in steps rather than dimming smoothly.
Here are the most common causes:
- The dimmer is not compatible with the lamp's LED driver
- The minimum setting on the dimmer is too low
- The dimming curve does not match the behavior of the specific LED bulb
- There is insufficient power at the dimmer (underload)
In many cases, adjusting the minimum setting is enough to eliminate the flickering. If that doesn't help, the next step is to use a dimmer with an adjustable dimming curve.
Which dimming curve is best suited for LED lighting?
For LED lighting, a logarithmic dimming curve works best, because LED bulbs naturally have a different brightness response than incandescent bulbs. A logarithmic setting compensates for the sensitivity of the human eye and ensures a smooth, controllable dimming experience from high to low.
LED bulbs respond differently to a reduction in power than incandescent bulbs. With an incandescent bulb, brightness decreases more or less linearly with power. With LEDs, the light output depends on the internal driver, which sometimes reacts unpredictably at low power levels. A logarithmic dimming curve accounts for this by making the steps smaller in the low range, precisely where LED bulbs are most sensitive.
In addition, always choose a dimmer that is specifically labeled as an LED dimmer and has an adjustable minimum setting. This allows you to adjust the lower limit to match the specific light bulb you’re using, which prevents flickering and outages at low settings.
How do you set a dimming curve correctly?
To set a dimming curve correctly, first adjust the dimmer’s minimum level until the light remains stable without flickering, and then check the maximum level to ensure it reaches the desired brightness. For dimmers with adjustable curves, you should then select the curve type that best suits your light and usage preferences.
Follow these steps to set it up correctly:
- Install the dimmer and connect the LED bulb you want to dim.
- Dim the light to the lowest setting and see if it stays steady or flickers.
- Adjust the minimum level using the adjustment screw or the settings menu until the light stays on steadily.
- Check the maximum brightness level and adjust it if the light is too bright or too dim at the highest setting.
- Select the curve type (linear, logarithmic, or S-curve) if the dimmer supports it, and test the transition across the entire range.
- Test the result by slowly dimming the light from low to high and checking that the transition is smooth.
Please note that the ideal setting may vary depending on the bulb. If you replace the bulb later, you may need to check the minimum setting again.
Which dimmers support adjustable dimming curves?
Dimmers with adjustable dimming curves are typically higher-quality digital LED dimmers, where the curve type and the minimum and maximum values can be adjusted manually or via software. Simple rotary potentiometer dimmers rarely offer this capability.
When choosing a dimmer with an adjustable curve, look for the following features:
- The term “adjustable minimum level” or “trim function” in the product specifications
- Support for multiple curve types (linear and logarithmic)
- Manufacturer's Compatibility List for LED Bulbs
- Digital controls or app integration for more precise settings
Smart dimmers with Zigbee, Bluetooth, or Wi-Fi often offer the most flexibility, since settings can be adjusted via an app without having to open the dimmer itself. For an overview of suitable options, check out our selection of LED dimmers and controls.
How Freelux Helps Ensure Proper Dimming of LED Lighting
Flickering lights, irregularities in the dimming curve, or a light that cuts out at low settings: these are frustrations we at Freelux know all too well. That’s why we’ve specifically designed our product line for use with modern LED lighting, focusing on compatibility, adjustability, and ease of use.
Here's what we offer:
- Digital LED dimmers with an adjustable minimum level and a logarithmic dimming curve for a smooth lighting experience
- Smart dimmers with Zigbee, Wi-Fi, and Bluetooth, compatible with Philips Hue, Homey, and KlikAanKlikUit
- Easy installation without any remodeling, compatible with existing wiring
- Wide power range and available in finishes that match standard System 55 frames
- Part of the WIIS® concept, which ensures that products are interchangeable and future-proof
Want to know which dimmer is best suited for your situation? Check out our full selection in the LED dimmer webshop or contact us for personalized advice.
Frequently Asked Questions
Can I dim any LED bulb with an LED dimmer?
Not all LED bulbs are dimmable. The packaging or product specifications will indicate whether a bulb is “dimmable.” If you use a non-dimmable LED bulb with a dimmer, the bulb may be damaged, behave erratically, or fail prematurely. Always check the compatibility of both the bulb and the dimmer before you begin.
What is the most common mistake made when setting a dimming curve?
The most common mistake is setting the minimum level too low, causing the light to fall just below its operating threshold and start flickering or turning off. Another common mistake is using an old dimmer originally designed for incandescent bulbs without adjusting the settings to account for how LEDs behave. Always start by carefully adjusting the minimum level, and then test the entire dimming range.
My dimmer works fine with one light, but it flickers when I turn on multiple lights. Why is that?
This is a typical sign of an underload or uneven load on the dimmer. Each LED bulb has its own driver with slightly different electrical characteristics, and when multiple bulbs are used, small differences can compound. Check that the total power of the connected bulbs falls within the dimmer’s recommended range, and reset the minimum level after adding additional bulbs.
Can you also set a dimming curve using a smart home system like Philips Hue or Homey?
Yes, smart dimmers compatible with platforms such as Philips Hue, Homey, or KlikAanKlikUit often offer advanced settings via their respective apps, including adjusting the dimming curve, setting minimum and maximum levels, and programming dimming schedules. This gives you much more control than a traditional dimmer with an adjustment screw, without having to physically open the dimmer.
How do I know if my current dimmer is compatible with LED lights, or if I need to replace it?
Check the product specifications or the nameplate of your dimmer for terms such as "LED," "dimmable LED," or a minimum wattage of 0–10W. If it only says "incandescent bulb" or lists a minimum wattage of 40W or higher, the dimmer is most likely not suitable for modern LED lighting. In that case, replacing it with a specific LED dimmer is the most reliable solution.
What is the difference between a leading-edge dimmer and a trailing-edge dimmer, and which one works better with LEDs?
A leading-edge dimmer (also known as a "leading edge" dimmer) cuts off the beginning of the AC waveform and was the standard for incandescent bulbs. A trailing-edge dimmer ("trailing edge") cuts off the end of the waveform and is gentler on the electronic components in LED drivers. For LED lighting, a trailing-edge dimmer generally works better because it causes less noise and responds more stably to the sensitive electronics in LED lamps.
How often should I check or readjust my dimming curve settings?
Generally speaking, you don’t need to adjust the settings regularly, unless you replace a bulb, add additional bulbs to the dimmer, or notice that the dimming behavior changes. Over time, LED bulbs may respond slightly differently due to wear and tear on the driver, which may require a minor adjustment to the minimum level. An annual checkup during heavy use is a good practice to prevent flickering issues.