How it works
The multiplier is target servings divided by original servings, defaulting to 6 ÷ 4 = 1.50, and the multiplier field or the quarter, half, 2× and 3× buttons override it whenever a positive number is present. Each pasted line is then scanned for its first number, understanding mixed forms like 1 1/2, plain fractions like 3/4 and unicode glyphs such as half and two-thirds. Results are rebuilt as the nearest friendly fraction below 10, whole numbers above 10, and whole grams for weight units.
Servings and the multiplier are the obvious levers, but the Convert imperial to metric button changes the output most. Turned on, it rewrites cups as ×240 ml, tablespoons ×15, teaspoons ×5, ounces ×28.35, pounds ×453.6, inches ×2.54 and Fahrenheit to Celsius. Turned off, any line whose unit looks like a time, temperature or length is deliberately skipped, so a 350°F oven and a 25 minute bake stay exactly as written while the ingredients scale.
Only the first number on each line is touched, so a line reading 2 eggs plus 1 for the wash scales the 2 and leaves the 1 alone. Unit detection is substring based, which means a word beginning with min, such as minced or mint, is mistaken for minutes and left unscaled. Beyond parsing, scaling is pure arithmetic: pan size, bake time, leavening and salt rarely scale linearly, and fraction rounding can drift a few percent on small amounts.
Frequently asked questions
How do I halve a recipe without retyping the servings? +
Press the half button, which writes 0.5 into the multiplier field and overrides the servings calculation entirely. The quarter, 2× and 3× buttons work the same way. Clear the multiplier field to go back to the servings ratio.
Why did the oven temperature stay the same when I scaled up? +
That is deliberate. Any number followed by a temperature, time or length unit — °F, °C, minutes, hours, inches, cm — is left untouched, because doubling a recipe should not double the bake temperature or the tin diameter.
Does the metric toggle turn cups into grams? +
No. It converts volume to volume, so a cup becomes 240 ml and a tablespoon 15 ml. Only ounces and pounds become grams. For a true volume-to-weight answer you need an ingredient density, which this tool does not hold.
What fractions does the output round to? +
Below 10 it picks the closest of one-eighth, quarter, third, three-eighths, half, five-eighths, two-thirds, three-quarters and seven-eighths, keeping any whole number in front. From 10 upwards it rounds to a whole number, and weights round to whole grams.
Can I scale a recipe written in fractions like 1 1/2 cups? +
Yes. The parser reads mixed numbers such as 1 1/2, bare fractions such as 3/4, decimals, and unicode fraction characters. It converts them to a decimal, applies the multiplier, then reformats the answer back into a cooking-friendly fraction.
What scales linearly and what does not
Ingredient quantities scale linearly and almost nothing else does. Doubling a recipe doubles the flour and the sugar correctly, and gets the pan size, the cooking time and the seasoning wrong.
Salt and strong spices are the usual casualties. Perception of saltiness does not track concentration linearly, and aromatics like chilli, garlic and clove concentrate during a longer cook, so a doubled batch seasoned by doubling frequently overshoots. Scale them at something under the full factor and adjust at the end, which is the one adjustment that has to be made by tasting.
Pan geometry is the constraint nobody checks
Doubling a cake batter and putting it in a pan of twice the area gives the same depth and roughly the same bake time. Putting it in the same pan doubles the depth, and a batter twice as deep does not bake in twice the time — it bakes at a lower temperature for considerably longer, or it burns outside and stays raw in the middle.
Area scales with the square of a linear dimension, which is the arithmetic that catches people: a 9-inch round pan has about 27% more area than an 8-inch one, not 12.5%. Two 8-inch pans are closer to one 9-inch than most people assume, and that is usually the better answer than scaling the depth.
Roasting has the opposite problem: a doubled tray of vegetables steams instead of browning, because the same oven now has twice the moisture to drive off. Use two trays.
