The "speed=warp_factor^3" used for TOS is very straightforward and works well given the small speeds that Star Trek ships travel at. Actually the Sovereign's speed of warp 9.99 (on the TNG scale) corresponds to just a little below TOS warp 20 - a very manageable number.
What I do not understand however is why Roddenberry did not come with a proper formula for TNG scale, if he really wanted a revision of the old scale - OK, we do have a "speed=warp_factor^(10/3)" up to warp 9, but what happens between 9 and 10 is bogus, and the increase in speed is defined by nothing more than a drawing.
To cut a long story short, I came up with my own warp scale (I'll take the liberty to call it the "JohnWain warp scale" or JWW in short
![Smile :)](./images/smilies/icon_smile.gif)
JWW 1 = 1x speed of light
JWW 100 = infinite speed
The formula I have used is the following:
S(c) = (W^4 * 100 - 1)/(100-W)
where:
S(c) - multiples of speed of light
w - warp factor
It is clear that the larger the warp chosen, the smaller the denominator will be. At warp 100, the denominator is 0 and so the resulting speed is infinite. In the numerator, it was necessary to have the (-1) in order to obtain equivalence at warp 1 (the fraction for warp 1 is 99/99 = 1x speed of light). This formula allows for consistent results throughout the scale, and can plot any speed. (As an aside note, TNG 9.99 = JWW 9.203. However, other TV shows use much higher speeds for their ships. For example, in Stargate Atlantis, the City Ship travelled 3 million light years in a few hours (Enemy at the Gate episode). It is unclear exactly how long the journey took, but I would put the City Ship's speed between JWW 96-98, which makes this scale very comprehensive).
I have created a calculator in Excel for the scale. I will post a print screen here (my monitor resolution is 1366x768, which imposed the layout of the document):
![Image](http://imagizer.imageshack.us/v2/1024x768q90/834/b6nn.png)
You can download it and play with it. I have hosted it on MEGA. The file is virus free. It has two pages, the one print-screened above and one with several warp factor graphs (called Comparisons).
WarpFactor.xlsx
---