What do you define as buggy? The further away you get from the origin, the less precision you get behind the decimal point. If you want a table, I made one over here. The example I made was about Time.time which is also a float, however it applies to any single precision float just the same way. It’s always just a matter how fine you need your details.

Just as an illustration, I once made this very simplistic solar system diagram which includes only the sun, the earth and the moon, but to scale. Most drawings are not to scale and it leads to many misunderstandings about the actual distances and sizes involved.

Everything you see is a single shader. All shapes (the circles and the lines) are drawn in a single shader. That’s why you can zoom onto that circles quite far without seeing jagged edges as the circles are drawn using math. Anyways the key point here is that the center (0,0,0) is the center of the sun. The earth is 150 million km to the right. I did not use meters inside Unity. I can’t remember exactly but I think I used one unit is 10000km. So the earth is about 15000 units off the center / origin. You will notice that visually you shouldn’t have much issues. However dragging left and right at a high zoom level shows the floating point limitations. That far from the origin, the minimum possible step the position can make is a lot greater than close to the origin. If you have a moderate zoom, you would not notice that the panning actually snaps to certain point. However if you zoom quite far in you will see some floating point accuracy artifacts.

Just zoom in on the very top of the sun. At the top you can see the horizontal distance of your mouse cursor from the sun center (so only the horizontal distance, the distance on the x axis). If you zoom in so that the screen roughly covers 4 km (so ±2km) you will see that you can still pan perfectly fine to the left and right. However panning up and down already has issues since the top position of the sun is about 700000km away from the origin. Of course at that scale it’s only 70 units, but you will already notice the drop in accuracy.

Now try the same with the earth that is 150M km away from the origin. The distance display itself already snaps to increments of 100km. floats can’t give you more precision at that point. Always keep in mind that a floating point number only has a certain fix number of binary digits (single floats have 24 bits). The “floating” point defines where you put your “binary point” that seperates the whole number from the fraction. The more bits you need before the binary point, the less you will have behind it. Since number in a computer are based on the base 2, those changes happens at exact powers of 2 (2,4,8,16,32,64,128,256,512, …) Each time you cross one of these whole number marks you will loose one bit behind the decimal point. For really large numbers, floats can not represent fractions at all (just see the bottom of my table). Btw: the table does not end where I stopped. floats can go up to 10^38 but only have about 7 (decimal) digits of precision. So the largest number would have 38 digits, but only the seventh from the top can actually change at such high values.

Simply put, the smallest change a float can represent at a certain size is always the value of the least significant bit to the far right. See this interactive float visualization. Just enter a value, say about 1000. Flip the last bit and see how much the value actually changes. Now set the value to 10000 or 100000 and try the same thing again. You will notice that this smallest possible change would have gown by about 10 or 100 compared to if your value would be around 1000.

To sum up:

There is not really a generally valid size or distance at which you will see problems because it’s always a matter of scale and also depends on the usecase. Though single precision floats (32 bit, 23(+1) mantissa, 8 exponent, 1 sign bit) are quite limited. So having a so called floating origin is a quite common thing for large or open world maps.