How to thicken gravy, and the ratio for each way

Whisk 1 tablespoon of cornstarch into 1 tablespoon of cold water until there are no lumps, stir it into simmering gravy, and let it bubble for two minutes. That thickens about one cup. It is the fastest fix, it works on gravy that is already made, and the two minutes of simmering are not optional.

Everything else on this page is about which method to use when, and what to do when it has already gone wrong.

The ratios, in one table

Every method here thickens roughly one cup of gravy. Double them together and you get glue, so pick one and let it work before adding more.

Two things fall out of that table. Cornstarch needs half as much as flour, which is the single most common mistake, and arrowroot is faster than either but sets clear rather than opaque, so it looks wrong in a traditional roast gravy and right in a glaze.

How much do you need for your pan?

Set how much gravy you are thickening and every ratio above is multiplied for you. Pick one method and let it work, rather than stacking two.

Cups of gravy

2

about 480 ml

Method	What to measure	Simmer
Cornstarch slurrycornflour in the UK	2 tbsp cornstarch + 2 tbsp cold water	2 min
Flour slurryplain flour	4 tbsp flour + 4 tbsp cold water	5 min
Roux, made firstbefore the stock goes in	2 tbsp butter + 2 tbsp flour	5 min
Beurre maniékneaded to a paste	2 tbsp soft butter + 2 tbsp flour	3 min
Arrowroot slurrysets clear, not opaque	1 tbsp + 1 tsp arrowroot + 4 tbsp cold water	1 min
Reductiondeepest flavour	Nothing added, you just end up with less	10 to 20 min

Cups are US cups, 240 ml. Quantities are a starting point rather than a rule: how much your gravy needs depends on how much fat and gelatine is already in it.

Which to use, and when

Use cornstarch when the gravy is made and the guests are sitting down. It is the fastest of the starches, it needs the least, and it does not need cooking out. Its weaknesses are that it thins again if you hold it over heat too long, and it does not reheat as well the next day.

Use flour when you have five minutes and want the matte, old-fashioned look of a Sunday-roast gravy. Raw flour tastes like raw flour, which is the whole reason for the five minutes.

Use a roux when you have not made the gravy yet. Cooking the flour in fat first is the difference between gravy that tastes of stock and gravy that tastes of the roast, and no slurry added later gets you back to it.

Use beurre manié when you meant to make a roux and did not. Knead equal parts soft butter and flour into a paste with your fingers and whisk small pieces into the simmering gravy. It is a roux you make at the end instead of the beginning, and it is the trick most worth knowing here.

Use reduction when the flavour is already good and you simply have too much liquid. It concentrates salt as well, so taste before you season.

Should you use cornstarch or flour?

Cornstarch if you want it thick in two minutes and glossy. Flour if you want it opaque and you have five. That is genuinely the whole decision for most gravy.

The one that decides it for some people is what happens afterwards. Flour-based gravy reheats and freezes well. Cornstarch-based gravy can turn thin and slightly weepy on the second day, which matters if you are making it ahead.

Gluten-free gravy

Cornstarch, arrowroot and tapioca are all naturally gluten free, so the easiest gluten-free gravy is a cornstarch slurry into good stock. Use 1 tbsp per cup, exactly as above.

Two things to check rather than assume. Stock and gravy granules are the usual hidden source of gluten, not the thickener, so read the tub. And a roux made with a gluten-free flour blend behaves differently from a wheat roux, because those blends are usually mostly starch already: start with about half the flour you would normally use and add more only if you need it.

More on the alternatives, with the ratio each one needs, on our cornstarch substitutes page. If you are cooking from the UK, cornstarch is what you know as cornflour, and the same page covers why American corn flour is a completely different product that will not thicken anything.

Fixing gravy that has already gone wrong

Lumpy. Whisk hard first, because most lumps break up. If they do not, pour the gravy through a sieve. This is not a failure, it is what sieves are for, and nobody at the table will know.

Not sure how much to use. The amount depends on how thick you want it rather than what is in the pan, and there is a calculator for that on how much cornstarch to thicken.

Still thin after a slurry. You almost certainly did not simmer it long enough. Starch needs to reach a proper simmer to thicken, and gravy that is hot but not bubbling will stay thin no matter how much you add. Give it two full minutes before deciding it has not worked.

Too thick. Loosen it with warm stock rather than water, which thins the flavour along with the texture.

Went thin again after sitting. That is cornstarch breaking down over long heat. Take it off the heat, or use flour if you know it is going to sit.

Greasy. Skim the fat off the top with a spoon, or drop in an ice cube and lift the fat as it clings. This is separate from thickness and no amount of starch will fix it.

Does any of this change the macros?

Barely, and it is worth saying plainly on a site that spends most of its time on macros. A tablespoon of cornstarch is around 30 calories and 7 g of carbohydrate, split across a whole jug of gravy, so a serving carries a gram or two.

The fat skimmed off the top of the roasting tin is a far bigger number than the thickener, and the portion you pour is bigger than either. If you are watching macros over a roast dinner, the gravy thickener is not the place to look.

Figures are estimates from typical ingredient values rather than measurements.