Sauce thickening calculator

There are several ways to thicken sauces, many of them rely on the ratio of thickening agents to liquid you use. Because I'm lazy, this is a tool for calculating how much you need for a given amount of liquid depending on how thick you want the result.

Note that the default amount is scaled to 300 ml, which is the regular sized cream/heavy cream packages in Norway as they are (were?) in 2022.

Amount of liquid ml
Thickening agent Thickness
Thin Medium Thick
Roux - light Flour: 13.5 g Flour: 18 g Flour: 27 g
Fat:  9 g Fat:  12 g Fat:  18 g
Roux - dark Flour: 27 g Flour: 36 g Flour: 54 g
Fat:  18 g Fat:  24 g Fat:  36 g
Cornstarch 6.75 g 9.5 g 13.5 g
Potato starch 6.75 g 9.5 g 13.5 g



Remember that sauces tend to thicken as they cool down. The temperature you will eat it at will generally be lower than what you cook it at. So, if you like me love thick sauces, but feel that it often becomes too much (because you adjust the thickness while close to boiling), keep this in mind, and test for thickness after letting the sample cool down. For instance let it cool down for a bit longer on the spoon, or drizzle a couple of drops on a (not heated) plate before evaluating thickness.

Also bear in mind that starches thicken largely by having starch particles/molecules evenly dispersed in the liquid and then puffing up by absorbing/binding to the water. While some breaking down is neccessary for this to start being effective, if the starches break down too much, for instance by prolonged cooking or heavy stirring or blending, the thickening effect will be reduced.

For detailed explanations and to get a better idea of what's going on than what you can get out of this brief summary and amalgation of different sources on the net and experience, check out Harold McGee's "On Food and Cooking: The Science and Lore of the Kitchen" chapter about "Sauces thickened with flour and starch" (page 610 in the "First Scribner revised edition 2004" ISBN 978-0-684-80001-1). For traditional starches I think it does a better job of explaining than what you will find in Nathan Myhrvold et al's the "Modernist Cuisine: the Art and Science of Cooking" chapter on thickening with starches (page 20 in volume 4 in "First edition, 2011", ISBN 978-0-9827610-0-7).

Effects of properties of other ingredients on thickening


Salt (slightly) lowers gelation temperature.


Sugar (slightly) increases gelation temperature.

Acidis and alcohol

Acids and alcohols break down starch significantly. So the main effects are that dispersion occurs sooner, gellation at lower temperatures, and the result becomes less viscous/more fluid/less thick.

Starches from roots (for instance potato or tapioca) are more affected by acidity (effects noticeable from pH 5 and lower), while starches derived from grain (for instance wheat or corn) hold up better (effects noticeable from pH 4 and lower).


Properties for roux (wheat)
Gelation temperature 52 ℃ to 85 ℃
Works well with acidis Yes
Works well for being frozen and reheated Yes
Can be cooked for a long time Yes (stable)
Type Grain starch

Roux is the combination of fat and flour, cooked before adding cold liquid, or prepared ahead of time and added cold to warm liquid.

Pre-cook it for a longer time on higher heat to get a brown/dark roux. Note that if you cook it longer and/or hotter the starch breaks down more and you need to use more flour to achieve the same effect.

If you prepare it ahead of time, you can cook it untill it is only light/blond, and brown it further by reheating just before you use it.

Starch is what does the magic, so high protein/bread flours result in less thickening.

Much of the thickening is due to the starch absorbing water, so higher moisture/more damp climate calls for more starch/flour.

Note that many source say to use a 1:1 ratio of flour to butter, but this is assuming volume, often tablespoons. A 3:2 ratio of flour to fat seems to be the thing when going by weight.


Properties for cornstarch
Gelation temperature 62 ℃ to 80 ℃
Works well with acidis No
Works well for being frozen and reheated No
Can be cooked for a long time Eh (somewhat stable)
Type Grain starch

Usage: Mix 1 to 1 with cold water before mixing into the hot sauce.

You can use more water, it will thicken more slowly, reducing the chances of lumps. 1 part cornstarch to to 2 parts water is sometimes recommended as a safer amount. But, beware that increasing the amount of water for the slurry not only increases cooking time, but if using substantially more you also should stop and consider if it will dilute the taste.

Some sources say that cornstarch will loose thickening power over time as it is cooked.

Generally cornstarch is supposed ot have about twice the thickening power of flour. However, according to some sources thickening happens most effectively at about 80 ℃ - 85 ℃, signifficantly above the about 50 ℃ to 55 ℃ where the thickening power of flour supposedly realy starts to kick in.

Potato starch

Properties for potato starch
Gelation temperature 62 ℃ to 65 ℃
Works well with acidis No
Can be cooked for a long time No (unstable)
Type Root starch

Breaks down and looses thickening power if stirred much.

Tapioca (cassava)

Properties for tapioca derived from cassava
Gelation temperature 52 ℃ to 65 ℃
Can be cooked for a long time No (unstable)
Type Root starch

Lumps and dries in contact with hot air.


Properties for arrowroot
Gelation temperature 60 ℃ to 86 ℃
Can be cooked for a long time No (unstable)
Type Root starch

Works poorly with dairy.