OUR CALCULATION METHODS
Clear About What Is Exact and What Is Approximate
SinOrSlim uses straightforward mathematics wherever possible. Some cooking conversions, ingredient substitutions and oven-to-air-fryer estimates, however, depend on practical assumptions rather than exact equivalence.
This page explains how the current tools calculate or process their results, what is done automatically and where normal cooking or appliance variation can affect the answer.
Recipe Scaling
The Recipe Scaler calculates a single multiplier from the original and desired number of servings.
Each ingredient quantity that begins with a recognized number or fraction is multiplied by that same value.
Text without a starting quantity, such as “salt to taste”, remains unchanged.
Example
Original servings: 4
New servings: 6
6 ÷ 4 = 1.5
Every quantified ingredient is multiplied by ×1.5.
Cooking-Friendly Fractions
A mathematically exact decimal is not always a useful kitchen measurement. The Recipe Scaler therefore tries to display familiar fractions where the result is sufficiently close to a normal cooking quantity.
For awkward cup fractions, it may also provide a combination of cups and tablespoons.
2.25 cups → 2 1/4 cups
1.125 cups → 1 cup + 2 tablespoons (tbsp)
1.875 cups → 1 3/4 cups + 2 tablespoons (tbsp)
WHOLE-RECIPE ADAPTATION
How the Recipe Adapter Works
The Recipe Adapter applies the same serving multiplier used by the Recipe Scaler across a pasted ingredient list. It can then keep the original measurement system or convert recognized compatible measurements to US or metric units.
Serving multiplier
= new servings ÷ original servings
Adapted ingredient quantity
= original quantity × serving multiplier
Conservative Parsing
The adapter changes lines it can recognize confidently. Section headings, notes and lines it cannot safely interpret are preserved rather than guessed.
Same-Kind Unit Conversion
Weight is converted to weight and volume to volume. The adapter does not infer ingredient density to turn a volume such as a US cup of flour directly into grams.
Cooking Instructions Stay Separate
Cooking times, oven temperatures, pan sizes and cooking methods are not scaled automatically because they do not change in a simple proportion with ingredient quantity.
Weight and Volume Conversions
Weight → Weight
Conversions between grams, kilograms, ounces and pounds use fixed mathematical conversion factors.
These are exact apart from display rounding.
Volume → Volume
Conversions between milliliters, liters, cups, tablespoons, teaspoons, fluid ounces and pints use fixed volume relationships.
US and UK units are treated separately.
Volume ↔ Weight
Converting cups or milliliters to grams requires an estimate of the ingredient’s density.
These conversions are approximate.
INGREDIENT DENSITY
Why Cups to Grams Can Only Be Approximate
A cup measures volume. Grams measure weight. The relationship between them therefore depends on the ingredient.
The Cooking Converter uses an approximate grams-per-US-cup value for each supported ingredient and converts that into a working density.
Actual results can vary with brand, moisture content, how finely an ingredient is ground and how tightly it is packed into the measuring cup.
Examples Used by the Converter
All-purpose flour → 120 grams (g) per US cup
Granulated sugar → 200 grams (g)
Butter → 227 grams (g)
Milk → 245 grams (g)
Olive oil → 216 grams (g)
Honey → 340 grams (g)
Pan Size Calculations
Round Pan
Area = π × radius²
Square Pan
Area = side × side
Rectangular Pan
Area = length × width
The new pan area is divided by the original pan area to produce the ingredient multiplier.
This assumes that you want the mixture to remain at roughly the same depth. Pan depth, material and shape can still affect baking behavior.
Temperature Conversions
Fahrenheit and Celsius conversions use the standard mathematical formulas.
Fahrenheit (°F) = (Celsius (°C) × 9/5) + 32
Celsius (°C) = (Fahrenheit (°F) − 32) × 5/9
The displayed result may include decimals, while recipes commonly round to a practical oven setting. Real ovens can also run hotter or cooler than their displayed temperature.
OVEN TO AIR FRYER
How the Oven to Air Fryer Converter Works
Oven-to-air-fryer conversion is not an exact mathematical equivalence. Air fryers circulate hot air in a smaller cooking chamber, but results vary with the appliance, basket size, food quantity and recipe. The converter therefore provides practical starting settings rather than a guaranteed cooking time.
Conventional Oven
The starting air fryer temperature is reduced by about 15 degrees Celsius (°C) / 25 degrees Fahrenheit (°F), and the original cooking time is multiplied by 0.80.
Convection Oven
Because a convection oven already circulates hot air, the converter keeps the starting temperature roughly the same and multiplies the original cooking time by 0.85.
The Early Checking Time
Start checking time
= estimated air fryer cooking time × 0.90
For example, a conventional oven recipe at 200 degrees Celsius (°C) for 30 minutes gives a starting air fryer setting of about 185 degrees Celsius (°C) for 24 minutes, with a first check at about 22 minutes.
A Starting Point
The result is an initial temperature and time to try, not a guarantee that every recipe will be finished at that point.
Appliance Variation
Air fryer wattage, basket size, preheating and how much food is loaded can all change the actual cooking time.
Check for Doneness
Food type, size and thickness also matter. Check food early and follow appropriate appliance and food-safety guidance.
INGREDIENT SUBSTITUTIONS
How the Ingredient Substitution Finder Works
Ingredient substitutions are not universal mathematical conversions. The finder therefore uses practical substitution ratios for specific ingredients and replacement options rather than treating different ingredients as exactly equivalent.
Displayed substitute amount
= recipe amount × substitution ratio
For example, a substitute used one-for-one will scale directly with the amount in your recipe. A replacement that needs twice as much will be multiplied by two.
Practical Ratios
Each substitution option has its own starting ratio. The amount is then scaled to match the quantity entered from your recipe.
Context Still Matters
A replacement may work well in one type of recipe and poorly in another. The finder therefore includes notes about suitable uses and possible changes to flavor, texture, moisture, browning or rise.
Not an Allergy Guarantee
The finder does not certify ingredients or products as allergen-free. If you are substituting because of an allergy or dietary restriction, check the labels of the specific products you use.
Substitutions are practical starting points rather than guarantees. Brand, recipe method and the role an ingredient plays in a particular dish can all affect the result.
RECIPE COSTS
How the Recipe Cost Calculator Works
The Recipe Cost Calculator uses the package price, package size and quantity used to calculate the proportion of the purchase price that belongs to the recipe.
Ingredient cost
= package price × (amount used ÷ package size)
Cost per serving
= total ingredient cost ÷ number of servings
Compatible Units
The calculator converts compatible measurements before applying the cost calculation, such as kilograms to grams, pounds to ounces or liters to milliliters.
Your Prices
No supermarket price database is used. The result depends entirely on the package prices and quantities you enter.
No Exchange Rates
The selected currency only controls how the result is displayed. Prices are not converted between pounds, dollars, euros or other currencies.
The current calculation includes the ingredient costs you enter. It does not estimate electricity, gas, delivery charges, equipment costs or the value of your time.
SHOPPING LISTS
How the Shopping List Generator Works
The Shopping List Generator is primarily an organizing tool rather than a cooking calculation. It reads one item per line, keeps the list in the browser and can combine exact duplicate ingredients when their quantities and units are compatible.
Exact Duplicate Matching
The tool does not assume that differently written ingredients are the same item. Combining is intentionally conservative to avoid merging ingredients incorrectly.
Local Browser Storage
The current list and checked state are stored locally in the same browser so the list can remain available while you move between SinOrSlim pages.
No Account Sync
The list is not uploaded to a SinOrSlim account or synchronized automatically between different browsers or devices.
Privacy and Processing
The current Recipe Adapter, Recipe Scaler, Pan Size Converter, Cooking Converter, Oven to Air Fryer Converter, Recipe Cost Calculator, Ingredient Substitution Finder and Shopping List Generator perform their calculations or processing in your web browser.
The recipe quantities, ingredient names, substitution selections, prices, cooking settings and shopping-list items you enter into these tools are not submitted to SinOrSlim for calculation or stored in a SinOrSlim recipe or shopping-list database.
Try the Tools
Adapt a whole ingredient list, scale a recipe, compare baking pans, convert measurements, adapt oven instructions for an air fryer, find an ingredient substitute, calculate what a recipe costs or build a shopping list.