Cups v grams: why can’t American and British cooks agree on food measurements?

Like most Americans, Samin Nosrat grew up in a home with cup measures in the kitchen. That said, they didn’t always get used. “My mom taught me in a more ‘old world’ way,” she says – measuring the water to cover rice with one of her knuckles, for instance. Nosrat, the author of cookbook Salt Fat Acid Heat and presenter of the Netflix show with the same name, has built a career on what she calls “sensory-guided cooking” – helping home cooks to build culinary instincts by understanding how ingredients behave – and so admits to having “a somewhat tortured relationship with measurements”. But as a recipe writer, she describes herself as “neurotic”. “If I’m going to write recipes which are clear and which work,” says Nosrat, “it just makes sense to use scales. I have three sets.”

There is a chasm between Europe and America’s kitchen cultures. The fundamental difference is that Americans use volume, not weight, to make measurements in their kitchens. Cooking with cups is volume-based and relies heavily on visual cues – everyone knows what a cup of granulated sugar looks like; less so 200g or 7.1oz – while the metric system is weight-based. “The issue isn’t that Americans weigh things differently,” says Sarah Chamberlain, a writer who Americanises British cookbooks for the US market. “It’s that most of them don’t weigh things at all.”

Most US households don’t have a set of scales, agrees Claire Ptak, the London-based Californian pastry chef who made Meghan and Harry’s wedding cake. Ptak has written three cookbooks and for years has been banging a drum for her American readers to invest in scales; her own mother has only just bought a set more than 20 years into her daughter’s career as a professional baker.

“It’s dawned on me how narcissistic it is,” says Nosrat, “that we in the US insist on the cup system when the rest of the world cooks in another way.” She likens the conversion between cups and metric measurements to translation, “but not one that needs to be there. Actual languages are intrinsic to cultures and date back thousands of years. But [the language of cups] is just so arbitrary.”

There’s a big sentimental strand to all this that is not to be underestimated. Baking pros and Europeans can fly the flag for using scales and the metric system all they like, but what if people just like using their cups? Critiques of the cup volume system can strike at something elemental – tribal, even – in American cooks. As Chamberlain says: “It’s telling someone the thing they first got programmed to do was wrong.” Add to that the fact that sets of cup measures sometimes get handed down through generations, and that many people learned to cook this way from now-absent family members, and you can understand why the issue becomes emotionally charged.

Though she describes herself as “a bilingual cook”, Chamberlain prefers weighing things using the metric system, “because the numbers multiply and divide more easily”. Food professionals seem universally to prefer grams and milligrams to cups for their accuracy. Celebrated American baker and author of 14 cookbooks Dorie Greenspan now develops all her recipes in metric, which a tester then calculates in cups; the resulting books are published with dual measurements. Greenspan says it took a lot to convince her publishers to do this: “They were worried American readers would find the metric measurements intimidating.” Nosrat, meanwhile, has been known to pack a digital scale in her suitcase when travelling.

Cups are thorny territory for anyone who edits recipes for audiences on both sides of this transatlantic divide. The conversion to a metric (or any) weight depends on almost countless variables, from the ingredient you are measuring (a cup of flour weighs much less than a cup of brown sugar, for example) – but also within ingredient categories (a cup of unrefined brown sugar is heavier than, say, one of caster [superfine] sugar) – to how tightly or loosely you pack an ingredient into a cup. It also depends on your own particular set of cups; Chamberlain’s are beautifully rounded and smooth – it’s easy to empty them – but, she says, “getting stuff out of the bottom edges of a cylindrical cup is a pain in the ass”.

Some ingredients are trickier than others, too. Words such as “nightmare” and “headache” are universally applied to flour. According to Greenspan, “you can weigh a cup of flour 10 times and get a different measurement – there are different types of flour, but also the flour might be old, or dry, or there might have been humidity. I always aerate the flour bin, then scoop and sweep [or level it off]. My cup of flour is 136g. King Arthur Baking makes it 120g. Some others go as high as 150g.” This kind of discrepancy makes for wildly varied results, not least if you scale up a recipe by, say, four. “A couple of grams’ difference doesn’t change much in a single batch,” Ptak says, but if you’re quadrupling a recipe, a small difference in the definition of cup volume becomes very significant. As Lara Hamilton, owner of Book Larder, a culinary bookstore in Seattle, puts it: “This can be the difference between a moist, fluffy cake and a dry, dense one.”

Other problematic ingredients include fresh herbs, because, as Chamberlain explains, they are hard to judge: they’re light and can include stems, leaves or both. Measuring sticky things is annoying in cups, too, she says: “Peanut butter, molasses, honey … The trick is to oil your cup before you add the sticky thing. And this is where grams are good: you can just dump the sticky thing in a bowl on the scales.” And, of course, you save on washing-up. “If you used a cup for molasses which you then need to use for flour,” says Nosrat, “you have to stop everything to wash it. Scales make me so much saner!”

When I was very young, my mother had cast-iron balance scales to which we added weights on one side and dry ingredients to the brass bowl on the other until they were perfectly balanced. Each was then added to another bowl one by one. It was romantic but cumbersome. I remember the day Mum bought digital scales and how they changed the game – suddenly, we could measure all our dry ingredients in one bowl, the wet in another, combine the two and there was a cake in the oven in minutes. Most people who have acquired digital scales do not look back, it seems. As Greenspan says: “I no longer know what the benefit of cups is, other than comfort – if that’s how you learned or how your mother or grandmother did it.”

Is the tide changing in the US? Lara Hamilton isn’t convinced that Americans are being converted to scales, but she has noticed more customers at Book Larder buying imported European cookbooks than waiting for the US edition with cup measures. Nosrat tells me that her dream is to wax so lyrical about scales in her next book that she contributes to a “sea change” in American cooking.

Everyone agrees that it is to baking recipes, and bakers, that scales will make the most difference. Ptak, who was pastry chef at Alice Waters’ Berkeley institution Chez Panisse until 2005, says it was only around that time that the restaurant stopped using cups for all their desserts. She left Chez Panisse for London, where, she says, it was rare for restaurants to have a dedicated pastry chef. Their increased recognition in kitchens – the River Cafe went from having no one dedicated to pastry when Ptak worked there to about 20 people in the section now – dovetailed with the surge in popularity of cupcakes and home baking thanks to the likes of Sex in the City and then, in 2010, The Great British Bake Off (AKA The Great British Baking Show in the US). Suddenly, sales of stand mixers and cupcake trays and, yes, digital scales surged.

Chef and TV personality Gail Simmons, who presents hit show Top Chef agrees that, thanks to television and social media, home cooks are more knowledgeable and detail-oriented than they’ve ever been. But, she adds, “people like to think of cooking as improvisational”. Does using a scale shatter the idea of cooking as something for which you can have a gift or an innate intuition? “I always say that you can improvise in cookery when you have the foundations – when you know the ratios, the substitutions, the way ingredients behave,” Simmons says. “And the only way to get those is to follow a recipe accurately, which means using scales!”

And what of the way we publish recipes at the Guardian? As a UK publication with a global audience, and a predominantly British roster of chef contributors, we provide weights in grams, although we’ll often simplify, say, 500g courgettes (zucchini) to three medium ones. And, for smaller measurements, we follow the American model, preferring a teaspoon to 6g salt or a tablespoon to 20g maple syrup. Still, Simmons says that the “one lemon”, “a handful of parsley” and “a good pinch of salt” she sees in our recipes are “much more casual than an American recipe”.

A common thread in all of this is ease – sometimes that means cups, when making things out of habit or nostalgia. At weekends, Ptak makes breakfast pancakes for her daughter with cups; Simmons cooks a bread pudding from memory with eight to 10 cups of croutons and a half-cup of sugar. And while Nosrat insists on having three digital scales to hand – her hardware store favourite, another with a pull-out display for large batches of things and jeweller’s scales reserved mostly for precise salt measurements – she still describes herself as a sensory cook. “Taste, taste, taste,” she says, “that’s the source of my sensibility.”