How do you scale a recipe from 4 servings to 6 without redoing every fraction?
Short answer: The Recipe Scaler multiplies the number at the start of each ingredient line by desired servings divided by original servings. Going from 4 to 6 servings uses a factor of 1.5, so 1 1/2 cups flour becomes 2.25 cups. Results are shown as decimals rounded to at most 3 places, and lines with no leading number, such as "salt to taste", stay unchanged.
Key facts
- The Recipe Scaler computes one factor, desired servings divided by original servings, and applies it to every line that starts with a number.
- Both serving fields accept any value from 0.01 to 100,000, and they start at 4 (original) and 6 (desired).
- A leading amount can be a whole or decimal number (1.5 or 1,5), a slash fraction (3/4), a mixed number (1 1/2), or a fraction character from the set ½ ⅓ ⅔ ¼ ¾ ⅛ ⅜ ⅝ ⅞, alone or after a whole number (1½).
- Scaled amounts always come out as decimals with at most three decimal places, so ½ tsp times 1.5 appears as 0.75 tsp, not ¾ tsp.
- Everything after the number is copied exactly as typed, which means units, ingredient names and plural endings are neither converted nor corrected.
- Lines that do not start with a number, including notes, headings, blank lines and bulleted lines such as "- 2 cups water", are returned unchanged.
- The scaling script makes no network requests, so the ingredient list is processed in your browser tab.
How to use the Recipe Scaler
Picture a four-serving chili recipe and six people at the table. That is the setup these steps use.
- Enter the yield the recipe is written for in Original servings (4 in this case).
- Enter the number of portions you need in Desired servings (6 here).
- Paste the ingredients into Ingredients (one per line), keeping the amount at the very start of each line.
- Click Scale recipe. The scaled list appears in the result panel, and the status line reports the factor, for example "Scaled by 1.500×".
Formula and rounding
factor = desired servings / original servings
scaled amount = leading amount x factor
mixed number = whole + numerator / denominator (1 1/2 = 1 + 0.5 = 1.5)Servings are plain counts, and the leading amount is whatever number the line starts with. The calculation uses the exact ratio, so 100 / 6 is not rounded before multiplying.
Only the displayed result is rounded. Each amount is formatted to at most three decimal places with trailing zeros dropped, and large values get thousands separators (1,250). The factor in the status line is also shown to three decimals.
Worked example: 4 servings to 6
With Original servings set to 4 and Desired servings set to 6, the factor is 1.5. This is the real output for these five lines.
| Line you paste | Line you get | What happened |
|---|---|---|
| 1 1/2 cups flour | 2.25 cups flour | 1.5 x 1.5 |
| 2 eggs | 3 eggs | 2 x 1.5 |
| ½ tsp salt | 0.75 tsp salt | 0.5 x 1.5 |
| 3/4 cup milk | 1.125 cup milk | 0.75 x 1.5; "cup" is not pluralized |
| Salt and pepper to taste | Salt and pepper to taste | No leading number, copied as is |
Lines that trip up the parser
The scaler reads one number from the very start of each line. Most surprises come from that rule.
- A range such as "2-3 cloves garlic" scales only the 2. At a factor of 2.5 it becomes "5-3 cloves garlic", so put each end on its own line and rejoin them yourself.
- A comma between digits is read as a decimal comma, so "1,200 g flour" is treated as 1.2 g. A space has a similar effect: "1 200 g" is read as 1. Type 1200 instead.
- A bullet or dash at the start of a line hides the amount, so "- 2 cups water" is left alone. Strip bullet characters before pasting.
- Any number at the start of a line is treated as an amount, including a temperature. "350°F oven" at a factor of 3 turns into "1,050°F oven", so keep non-ingredient lines out of the list.
- A fraction with a zero denominator (1/0) or a decimal over a denominator (1.5/2) cannot be parsed, so that line comes back unchanged.
Turning decimals back into measuring-spoon amounts
The scaler returns 1.125 cup, but no measuring cup has a 1.125 mark. A few US kitchen equivalents cover most cases: 1 cup is 16 tablespoons, and 1 tablespoon is 3 teaspoons.
- 1.125 cup milk is 1 cup plus 2 tablespoons, since 0.125 cup is 2 tablespoons.
- 0.75 tsp salt is ½ tsp plus ¼ tsp, and 0.125 tsp is a 1/8 tsp measure.
- 1.5 eggs (the result when 2 eggs go from 4 servings to 3) is one whole egg plus half of a beaten one.
Why a straight multiple does not always taste right
The tool does arithmetic, and cooking is not always linear. Doubling a cake batter into the same pan gives a deeper cake that needs more time, or one that overflows. Use a larger pan or bake two.
Salt, spices and leavening are the usual trouble spots in big batches, and many cooks add a little less than the multiple and then taste. For very large jumps the numbers get awkward: going from 6 to 100 servings gives a factor of 16.667, which turns 1/8 tsp saffron into 2.083 tsp and 500 g potatoes into 8,333.333 g. Round those to something you can actually weigh.
What this tool does not do
- It does not convert units (cups to grams, °F to °C) or fix grammar, so 1 1/3 cups rice scaled from 4 servings to 3 comes back as "1 cups rice".
- It does not read amounts that come after the ingredient name ("flour, 2 cups") or a second amount on the same line, so in "1 cup (240 ml) milk" only the 1 is scaled.
- It does not change numbers inside cooking instructions, nor cooking time, temperature or pan size.
- It does not return fractions, nutrition values or costs.
Frequently asked questions
How do I scale a recipe from 4 servings to 6?
Enter 4 in Original servings, 6 in Desired servings, paste the ingredients one per line and click Scale recipe. The factor is 6 / 4 = 1.5, so a line starting with 2 cups comes back starting with 3 cups.
Does the recipe scaler understand fractions like 1/2 and 1 1/2?
Yes, it reads slash fractions (3/4), mixed numbers (1 1/2), fraction characters such as ½ or ¾, and decimals. The fraction has to be the first thing on the line.
Why does my result show 0.75 instead of ¾?
The scaler always outputs decimals, rounded to at most three decimal places. Convert them yourself, for example 0.75 tsp is ½ tsp plus ¼ tsp.
What happens to ingredient lines that do not start with a number?
They are copied unchanged. That keeps notes such as 'salt to taste' and any heading lines intact, but it also means you must adjust those lines by hand if needed.
How do I scale a range like 2-3 cloves of garlic?
Scale the two ends as separate lines, because the tool reads only the first number. At a factor of 2.5, '2-3 cloves' becomes '5-3 cloves', which is wrong.
Can I scale to half a serving or a fractional number of servings?
Yes, both serving fields accept any value from 0.01 to 100,000. Outside that range, or with an empty field, the tool shows an error asking for positive serving counts.
Does it convert cups to grams or change the cooking time?
No. It only multiplies the leading number on each line and keeps the rest of the text, so units, cooking times, temperatures and pan sizes stay exactly as you typed them.
Is my ingredient list uploaded anywhere?
No. The scaling script makes no network requests, so the list is processed in your browser and the result is shown on the same page.
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