This question really made me curious. Where I live (Romania, developing country within Eastern Europe), it's the same: soy milk is (much) more expensive than cow's milk.
The price difference has many causes. To name a few:
- subsidies from the government
- organic farming is usually done on a smaller scale, leading to a smaller volume of obtained food
- production cost for organic farming
- much less demand for soy milk as opposed to cow milk. This source indicates about 200-300 litres/year/capita for cow milk, as opposed to less than 1 litre/year/capita for soy milk according to this source. This is especially important, because much of the cost (for many products) is derived from fixed costs, so products sold in large quantities have an advantage.
- high gross margins for producers. An example is Vitasoy International Holdings Ltd which reported a Gross margin of about 50% in the recent year.
It is very hard to estimate the price if soy milk volumes would be at the same order of magnitude with those of cow milk. According to this source, production cost for milk in UK is about 0.62 pounds (0.77$ or 0.73€).
As suggested, I will try to improve the answer by providing extra information about soy milk production cost.
According to this simple recipe, home made soy milk costs about 0.5$ per 2.75 quarts (2.6 liters) which is 0.2$ per liter.. So, it is clearly less expensive than cow milk and much cheaper than commercial soy milk (if time, effort, electricity and other small factors are ignored).
Results can be improved by using specialized devices such as this one (about 129$ when writing this answer).
From the industrial perspective, it is not efficient to obtain soy milk only, but to also obtain other products from soy, to alleviate fixed costs (equipment, salaries, power etc.).
According to this source the following are the costs for equipment required for processing in various scenarios:
- The French Oil Mill Machinery Company example 1 - 1570 grands
- The French Oil Mill Machinery Company example 2 - 647 grands
- Example 3 - 112 grands
So, in most cases the initial investment is quite big. The final cost will depend on many factors such as salaries, power bills, equipment maintenance.
One important aspect is that not only money would be saved, if people switched to soy-milk. According to this article:
Cornell University scientist, David Pimentel, has found it takes about
14 kilo-calories (kcal) of fossil-fuel energy to produce 1kcal of milk
protein using conventional milk production. Organically produced milk
might require a little less than 10kcal of fossil-fuel energy per
In comparison, Pimentel’s data suggests that in a conventional soybean
production system, one kcal of fossil energy invested produces about
3.2kcal of soybean. For 1kcal of fossil energy invested in organic soybean production, you get an average of 3.8kcal of soybeans. This
means it takes between .26 and .31kcal of fossil fuel to make 1kcal of
soybeans (contrasted with 10-14kcal to make 1kcal of dairy milk
The water footprint of the soy milk products analysed in this study
was 28% of the water footprint of the global average cow milk.
Another important environmental parameter to consider is how much
phosphorus is used to produce food. Modern agriculture is dependent on
phosphorus derived from phosphate rock. It’s a non-renewable resource,
and current global reserves may be depleted in 50 to 100 years. Meat
and livestock production are associated with high phosphorus use and a
vegetarian diet demands significantly less phosphate fertilizer than a
Without more precise information, it is really hard to answer your questions. But one thing is sure: under the same conditions (subsidies, volume) soy milk would be significantly both cheaper and environmentally sustainable than cow's milk.