Grams to cups: why the ingredient matters
Grams measure weight and cups measure volume, so no single number turns one into the other. A level US cup of all-purpose flour weighs about 120 g, granulated sugar 198 g and honey 336 g, so 100g to cups is about 0.83 cups of flour but half a cup of sugar. The converter divides by the weight of one cup of the ingredient you pick, and multiplies to convert cups to grams. Weight to weight (ounces to grams) and volume to volume (cups to tablespoons) are fixed conversions that don’t depend on the ingredient.
Salt shows how much this matters. In King Arthur Baking’s chart a tablespoon of table salt weighs 18 g, Morton kosher salt 16 g and Diamond Crystal kosher salt 8 g — so swapping kosher salt brands spoon for spoon halves or doubles the salt. To convert ml to grams, multiply by the ingredient’s density: water is about 1 g per ml, whole milk about 1.03 and honey about 1.42.
US, UK and metric measures are different sizes
| Measure | Millilitres | Defined by |
|---|---|---|
| US cup | 236.59 | NIST (8 US fluid ounces) |
| US nutrition-label cup | 240 | FDA labelling rule |
| Metric cup | 250 | Canada’s labelling rule |
| US fluid ounce | 29.57 | NIST |
| UK (imperial) fluid ounce | 28.41 | UK law, 1/20 of a pint |
| US pint | 473.18 | NIST (16 US fl oz) |
| UK pint | 568.26 | UK law (20 UK fl oz) |
| Tablespoon | 15 (US: 14.79) | FDA and Canada labelling; NIST |
| Tablespoon, 20 ml | 20 | Used in some recipes, including Delia Smith’s |
To convert British cooking measurements to American ones, weights carry straight over — both countries use the avoirdupois ounce (28.35 g) and pound (453.6 g) — but a British pint is 20 fluid ounces against the American 16, and each British fluid ounce is about 4% smaller. Convert metric cups and 20 ml tablespoons as millilitres, not as US cups and spoons; the converter lists both.
Dry to cooked: rice, pasta, quinoa, lentils and beans
Grains and pulses absorb water, so they grow by volume and by weight — but not by the same amount. The figures below come from the USDA Food Buying Guide, which publishes measured yields for school kitchens, with cup weights from USDA FoodData Central.
| Food | 1 cup dry makes | Weight after cooking | Other published figure |
|---|---|---|---|
| White rice, long grain | about 3¼ cups | about 2.8× (worked out) | USA Rice: 1 cup → 3 cups |
| Brown rice, long grain | about 2⅞ cups | about 2.4× (worked out) | — |
| Spaghetti | — (weighed, not cupped) | 2.37× (al dente, 8 min) | Barilla: 2 oz dry ≈ 1 cup cooked |
| Penne | about 1½ cups | 2.60× (14 min) | — |
| Quinoa | about 2⅝ cups | 2.51× | Whole Grains Council: 1 cup → 3 cups |
| Lentils | about 3⅛ cups | about 3.2× (worked out) | USA Pulses: ½ cup dry → 1 cup cooked |
| Black beans | about 2 cups | — | — |
| Kidney beans | about 2½ cups | — | — |
The common mistake is to apply a volume ratio to weight. Rice triples by volume, but by weight it grows about 2.8 times: 100 g of dry long-grain rice makes about 278 g cooked, not 300 g. One cup of cooked white rice weighs 158 g in USDA’s data, although USA Rice puts it at about 8 oz (227 g) — how firmly the cup is packed makes that much difference, so weigh rice when the number matters. Sources also disagree on lentils: USA Pulses says half a cup of dry lentils makes one cup (twice the volume), while USDA’s measured yield is about three times.
Raw to cooked meat weight
Meat loses water and fat as it cooks. USDA’s Table of Cooking Yields for Meat and Poultry and the Food Buying Guide give the share of the raw weight that is left:
- Boneless skinless chicken breast keeps about 73% — 500 g raw becomes about 365 g. Boneless skinless thighs keep 63% after trimming.
- Ground beef keeps 69% (under 12% fat), 67% (12–22% fat) or 62% (over 22% fat) when pan-fried as crumbles.
- Grilled sirloin keeps 80% and rib eye 82%; a boneless pork loin chop, pan-fried, 77%; fish fillets about 70%.
- Bacon keeps only 32%.
If you track food, weigh it the same way every time: raw weight with a raw entry, or cooked weight with a cooked entry. Mixing the two for chicken breast is off by a quarter or more. For meal prep, run the converter backwards: to end up with 150 g of cooked chicken breast, start with about 205 g raw.
Cooks on calorie-counting forums report figures in the same range: one weighed 1,148 g of raw chicken breast down to 768 g after cooking it in a little fat, and a Seasoned Advice answer measured 200 g of dry pasta at 420 g drained and al dente. Their most reliable method is the batch method: weigh everything dry or raw, weigh the whole batch cooked, then weigh your portion and log that share of the raw weight.
Slow cooker: low vs high, and converting oven recipes
Montana State University Extension’s rule is that “one hour on HIGH generally equals two hours on LOW”, so 8 hours on low is about 4 on high. USDA says slow cookers work “generally between 170° and 280° F”, that it is safe to cook on low the whole time, and to use high for the first hour if you can. To convert an oven or stovetop recipe, the extension service publishes this chart:
| Recipe time | LOW | HIGH |
|---|---|---|
| 15–30 minutes | 4–6 hours | 1½–2 hours |
| 35–45 minutes | 6–10 hours | 3–4 hours |
| 50 minutes – 3 hours | 8–16 hours | 4–6 hours |
Use about half the liquid, because little evaporates under the lid (soups are the exception); fill the pot at least half and no more than two-thirds full; and keep the lid on — it can take 20 minutes to win back the heat. USDA’s rule for a slow cooker is “always thaw meat or poultry” first, and to put vegetables in first because they cook more slowly than meat. To convert a slow cooker recipe to the oven or stovetop, read the chart backwards.
The 2-to-1 rule is a guide, not a guarantee. Slow cookers differ by brand and age. One cook on r/slowcooking followed a recipe’s “8 on low or 4 on high” and found the pork shoulder “literally still rubber” after 4 hours on high — tough cuts need time to turn tender, not just heat. Whatever the setting, food in liquid can’t get hotter than boiling point (212 °F at sea level). To learn your own cooker, a Seasoned Advice answer describes America’s Test Kitchen’s check: put 4 quarts of water in a 6-quart cooker, run it on high for 6 hours and measure the temperature.
Slow cooker to Instant Pot
No pressure cooker maker publishes a slow-cooker conversion. The rule of thumb on recipe sites is hours on HIGH × 6 = minutes at high pressure: 4 hours on low (2 on high) becomes about 12 minutes, 6 hours on low about 18 minutes and 8 hours on low about 24 minutes. Treat that as the shortest likely time. Recipe charts disagree widely: the ones we read turn 8 hours on low into anything from 24 to 60 minutes, and beef stew alone into 15–20 minutes on one chart and 35 on another. Tough cuts such as chuck roast usually need 45–60 minutes.
For a stovetop or oven recipe, Presto’s pressure cooker manual says to cut the time by two-thirds: 45 minutes becomes 15. Its cooker runs at 15 psi (250 °F); an Instant Pot’s High setting is 10.2–11.6 psi, so electric cookers may need a little longer. Two things change when you convert: you need less liquid than a slow cooker, but at least the minimum — 1 cup in a 3-quart Instant Pot, 1½ cups in a 6-quart, 2 cups in an 8-quart and 2½ in a 10-quart — and the pot must not go past the PC MAX line, or half full for rice and dried beans. Going the other way, the Instant Pot’s own slow-cook setting maps Less, Normal and More to a traditional slow cooker’s low, medium and high — although owners on r/instantpot report that it runs cooler than a stand-alone slow cooker, so allow extra time. And the US National Center for Home Food Preservation does not recommend electric multi-cookers for pressure canning.
Pressure cooker whistles to minutes
Indian recipes often say “cook for 3 whistles”, and people regularly ask how long a whistle is. There is no fixed answer: cooks’ estimates on forums run from under 2 minutes to about 10 minutes per whistle, because the gap depends on the cooker’s size, how full it is and how high the flame is. The more reliable method, repeated across those threads, is to bring the cooker to full pressure on high heat, turn it down at the first whistle, and time from there — for example about 10 minutes for split dals and about 17 for whole dals. Electric pressure cookers such as the Instant Pot don’t whistle at all, so set the time directly.
Oven to air fryer
The widely repeated rule is 25 °F (about 15 °C) cooler and about 20% shorter, so 400 °F for 20 minutes becomes 375 °F for about 16. No air fryer maker we checked publishes that rule. Instant Brands suggests reducing time and temperature “by up to 25%” for its Omni oven, and Philips’ 2013 recipe book told owners to lower the oven temperature by 70 degrees and halve the time — for packaged foods only. USDA describes air fryers as “essentially countertop convection ovens” that cook most foods in 5 to 25 minutes at 350–400 °F, and warns not to cook raw, stuffed, breaded chicken breast products in one.
Convection and fan ovens
In the US the advice is to drop 25 °F. GE says to “reduce the temperature by 25 degrees Fahrenheit” and that most of its convection ovens do it automatically; KitchenAid’s ovens take off 25 °F (14 °C) and leave the time unchanged. UK oven makers say about 20 °C: Beko says 20 °C, AEG 20 °C and 10 minutes less per hour, and Hotpoint about 25 °C and 10 minutes per hour. 20 °C is 36 °F, so UK and US recipes adjust by different amounts. GE adds that food “often” cooks up to 25% quicker — check early either way.
Watch for two traps cooks keep running into. First, many US convection ovens subtract the 25 °F themselves, so taking it off again leaves the oven 25 °F cooler than intended; check what your oven shows after you set it. Second, a recipe that already says “fan 180 °C” has been converted — set 180 °C. The words differ too: what Americans call a convection oven is a fan oven in the UK.
Changing oven temperature: 350 to 325, 425 to 350
There is no reliable formula for how much longer food takes at a lower temperature. One calculator site uses about 12% per 25 °F, but gives no source, and the change depends on the food’s size and shape. A lower temperature always means a longer time, so start checking at the original time and judge by the inside of the food: USDA’s safe minimums are 165 °F (74 °C) for all poultry, 160 °F (71 °C) for ground meat, and 145 °F (63 °C) with a 3-minute rest for steaks, chops and roasts. The UK Food Standards Agency uses 70 °C held for 2 minutes. For baking, King Arthur Baking’s cupcake guide calls them done at an internal 205–210 °F.
Cake to cupcakes
King Arthur Baking puts a typical cake recipe at about 6 cups of batter — enough for a 9 × 13-inch pan, two 9-inch rounds or two dozen cupcakes. Its golden vanilla cake bakes for 30–35 minutes as 9-inch layers and 23–25 minutes as cupcakes. Advice on the time cut varies: King Arthur’s cupcake guide says about 5–10% shorter than 9-inch rounds and up to 40–50% shorter than a 9 × 13, while Handle the Heat bakes standard cupcakes for 18–22 minutes at 350 °F. Fill the cups about four-fifths full and test early. In the most-viewed Seasoned Advice answer on the subject, a baker expects 18–24 regular cupcakes or about 40 minis from most cake recipes, and changes only the baking time.
Microwave cooking times by wattage
A higher-wattage microwave cooks faster, USDA says, but it gives no formula. The usual estimate is time × pack wattage ÷ your wattage: 3 minutes at 1,100 W is about 4 minutes 43 seconds at 700 W. Treat it as an estimate — stir, check early, and let food stand at least 3 minutes, as USDA advises. Lower power settings are not a smaller microwave: USDA explains that medium (50%) power “means that the oven produces microwaves 50% of the time”, so 50% power for twice as long isn’t quite the same as full power. If you don’t know your wattage, time a cup of water on High: boiling in under 2 minutes means 1,000 W or more, about 2½ minutes about 800 W, about 3 minutes 650–700 W. UK packs also show a heating category from A to E; a Sharp manual explains it rates how well the oven heats small quantities of food (up to 500 g) and “does not represent the general performance of the oven” — so it is not a wattage.
Oven temperatures: °F, °C and gas mark
Recipes print rounded pairs, not exact conversions. Gas mark 4 is printed as 350 °F and 180 °C, although 350 °F is 177 °C, and gas mark 3 is printed as 325 °F and 170 °C although 325 °F is 163 °C. Each gas mark is one 25 °F step, from mark 1 at 275 °F to mark 9 at 475 °F. For an exact figure use the Fahrenheit to Celsius or Celsius to Fahrenheit converter; the oven tab shows the printed figure, the exact one and the fan setting.
Cooking at high altitude
Water boils at a lower temperature as you climb — 208 °F at 2,000 feet and about 198 °F at 7,500 feet, according to USDA — so food cooked in liquid takes longer: up to a quarter more time at 5,000 feet for meat and poultry cooked by moist heat. USDA suggests a slow cooker setting that holds food at 200 °F or more at altitude, and Presto adds 5% to pressure-cooking time for every 1,000 feet above 2,000. Colorado State University Extension advises raising baking temperature by 15–25 °F and trimming baking powder and sugar.