Binary Counter Loader
Four dots count from 0 to 15 in binary, each bit flipping at half the rate of the one to its right. steps() timing gives the hard on and off of real LEDs and the loop is exactly one count.
Also known as: binary loading animation, bit counter dots, counting dots loader.
HTML
<div class="ldr-binary-dots" role="status" aria-label="Loading"> <span style="--p:16"></span><span style="--p:8"></span><span style="--p:4"></span><span style="--p:2"></span> </div>
CSS
.ldr-binary-dots {
--s: var(--ldr-size, 48px);
--c: var(--ldr-color, #3b82f6);
display: flex;
gap: calc(var(--s) / 7);
}
.ldr-binary-dots span {
width: calc(var(--s) / 4);
height: calc(var(--s) / 4);
border-radius: 50%;
background: var(--c);
animation: ldr-binary-dots-bit calc(var(--p) * 0.25s) steps(1, end) infinite;
}
@keyframes ldr-binary-dots-bit {
0% { opacity: 0.25; transform: scale(0.7); }
50%, 100% { opacity: 1; transform: scale(1); }
}
@media (prefers-reduced-motion: reduce) {
.ldr-binary-dots, .ldr-binary-dots *, .ldr-binary-dots::before, .ldr-binary-dots::after, .ldr-binary-dots *::before, .ldr-binary-dots *::after {
animation-duration: 3s;
}
}Customizing this loader
- Color: set
--ldr-coloron the element or a parent. Currently previewing#3b82f6. - Size: set
--ldr-size. Every dimension in the snippet is derived from it. Currently previewing64px. - Speed: change the duration on the
animationshorthand. Delays on the children are relative, so they keep their rhythm. - Accessibility: the root carries
role="status"and anaria-labelso screen readers announce the wait. The reduced-motion rule at the end slows the animation for users who asked for less motion.