With a certain dosis of patience I was regarding the quantities involved in MQ developers, Ilford and Kodak developers mainly. I entered the data in a spread sheet and ordered the data by increasing Metol amounts. It was not that difficult to regard the graphics obtained with the amounts of the components having Metol quantity as independent variable. I came to the conclusion that the main components like Hydroquinone, Sodium Sulfite and Sodium Carbonate may be calculated with following rules:

The amount of hydroquinone is in most cases 1,82 times the amount of Metol.
The amount of Sodium Sulfite is 11,5 times the amount of Metol plus 30g that is the minimum such developers have in general. The amount of Sodium Carbonate is 45g minus 6 times the amount of Metol, it decreases as Metol increases. Finally the amount of Potassium Bromide has no exact rule, imho, just use an amount between 0 and 3 g/L. All quantities are given below for 1 Liter developer.

I am not 100% sure, of course, if my coefficients apply to most of the recipes, but I will cite some examples:

The developer D76 from Kodak has this composition (see my source here)

Metol - 2 g
Hydroquinone - 5g
Sodium Sulfite - 100 g
Sodium Carbonate - 0 g
Borax - 2g
Potassium Bromide - 0 g

With my equations, I would have following developer instead:

Metol - 2 g
Hydroquinone - 3,64 g
Sodium Sulfite - 53 g
Sodium Carbonate - 33 g
Borax - 0 g
Potassium Bromide - 0 to 3 g

But, if I take the amount of Hydroquinone as base (5 g), then I have another recipe:

Metol - 2,75 g
Hydroquinone - 5 g
Sodium Sulfite - 61,6 g
Sodium Carbonate - 28,5
Borax - 0 g
Potassium Bromide - 0 to 3 g

The last one is perahps 'more like' D76 than the first, with more Sodium sulfite and the Carbonate of this second calculated recipe beeing replaced by even more sulfite and borax.


Another example is D23 from Kodak, the simpliest developer with only 2 components (see my source here):


Metol - 7,5 g
Hydroquinone - 0 g
Sodium Sulfite - 100 g
Sodium Carbonate - 0 g
Potassium Bromide - 0 g

Here we could say, according to the equations proposed, the developer would be:

Metol - 7,5 g
Hydroquinone - 13,65 g
Sodium Sulfite - 116 g
Sodium Carbonate - 0
Potassium Bromide - 1 to 3 g

Here we find a big difference in the amount of Hydroquinone. The high level of Metol, let us say, from 5 g/L upwords, makes Hydroquinone superfluous and lead to very fine grain developer but low contrast. On the other extremity, when Metol is zero, hydroquinone must be higher than a certain threeshold, I think about 5 g/L is a realistic value but I found developers with much more than that and they are high contrast and not fine grain.

Now, let me give two more examples, that are more like the equations. Agfa/Ansco 40:

Metol - 4.5 g
Hydroquinone - 7.5 g
Sodium Sulfite - 54 g
Sodium Carbonate - 46 g
Potassium Bromide - 3 g

With the equations I propose, we would calculate pro liter:

Metol - 4,5 g
Hydroquinone - 8,19 g
Sodium Sulfite - 81,75 g
Sodium Carbonate - 18 g
Potassium Bromide - 0 to 3 g

These last two are not the same, but there is maybe another relation to be added, if we see more in detail the sum of Sodium Sulfite and Sodium Carbonate in bot is equal 100 g, more or less. This sum increases with the amount of developing agents, from 80 to 100.

Another example is following, GEVAERT G.214:

Metol 2 g
Hydroquinone 3 g
Sodium Sulfite (anhydrous) 25 g
Sodium Carbonate 16 g
Potassium Bromide 1 g

Calculated:

Metol - 2 g
Hydroquinone - 3,64 g
Sodium Sulfite - 53 g
Sodium Carbonate - 33 g
Potasium Bromide - 0 to 3 g

Disclaimer: This equations may be used only as starting points for a new developer, they are OK for Metol between 1 and 5 but not less and not higher. Because the number of combinations is infinit, I can not give any warranty for the success of developers following this equations.