Despite what many cookbooks suggest, rice-to-water ratios can’t simply be scaled up proportionally.
We have a rice pilaf recipe (see related content) that works without fail when made using 1 1/2 cups of rice, but many readers have written us to ask why they end up with an inch of mushy rice on the bottom of the pot when they try to double it. The reason is that, despite what many cookbooks suggest, rice-to-water ratios can’t simply be scaled up proportionally. After running a series of tests, we confirmed that rice absorbs water in a 1:1 ratio, no matter the volume. So in our original rice pilaf recipe, which calls for 1 1/2 cups of rice and 2 1/4 cups of water, the rice absorbed 1 1/2 cups of water. The remaining 3/4 cup of water evaporated. But here’s the catch: The amount of water that evaporates doesn’t double when the amount of rice is doubled. In fact, we found that when cooking a double batch of rice using the same conditions—the same large pot and lid and on the same stove burner over low heat—as we’d used for a single batch, the same quantity of water evaporated: 3/4 cup. Hence, simply doubling the recipe—increasing the amount of rice to 3 cups and the water to 4 1/2 cups—leads to mushy rice because there is an excess of water in the pot. The bottom line: To double our rice pilaf recipe, use 3 cups of rice and only 3 3/4 cups of water.