How to Convert a Recipe to Metric
Converting a US recipe to metric involves three things: switching volume measurements (cups, tablespoons) to weight (grams), converting oven temperature from Fahrenheit to Celsius, and converting any pan sizes from inches to centimeters. The biggest source of error is treating cups as a universal unit — a cup of flour and a cup of honey have very different weights, so each ingredient needs its own gram conversion.
Step 1: Convert Volume to Weight, Ingredient by Ingredient
This is the part people get wrong most often. "1 cup" means a different weight depending on what's in it. You cannot use a single multiplier for the whole recipe — each ingredient needs its own conversion based on its density.
| Ingredient | 1 cup = |
|---|---|
| All-purpose flour | 120-125g |
| Granulated sugar | 200g |
| Brown sugar (packed) | 200g |
| Butter | 227g |
| Milk | 240g |
| Honey | 340g |
| Rolled oats | 90g |
| Powdered sugar | 120g |
For ingredients not listed here, use the Cups to Grams Calculator, which covers a wide range of common baking ingredients with their individual density conversions.
Step 2: Convert Oven Temperature
US recipes use Fahrenheit; metric recipes use Celsius. The formula is °C = (°F − 32) × 5/9, but for everyday baking, these rounded reference points cover almost everything you'll need:
| Fahrenheit | Celsius | Gas Mark (UK) |
|---|---|---|
| 300°F | 150°C | 2 |
| 325°F | 165°C | 3 |
| 350°F | 175°C | 4 |
| 375°F | 190°C | 5 |
| 400°F | 200°C | 6 |
| 425°F | 220°C | 7 |
| 450°F | 230°C | 8 |
For exact figures or temperatures not listed, use the Oven Temperature Converter.
Step 3: Convert Pan Sizes
US recipes give pan dimensions in inches; metric recipes use centimeters. The conversion is straightforward (1 inch = 2.54cm), but pan size affects baking time and texture, so getting it right matters more than it might seem.
| US (inches) | Metric (cm) |
|---|---|
| 8-inch round | 20cm round |
| 9-inch round | 23cm round |
| 9×13-inch | 23×33cm |
| 8×8-inch square | 20×20cm square |
| Loaf pan (9×5-inch) | 23×13cm |
If the exact size isn't available, round to the nearest standard size rather than using an odd in-between size — most metric bakeware comes in fixed sizes similar to US pans, just in centimeters.
Step 4: Convert Weight-Based Ingredients (Meat, Produce)
Some ingredients are already given by weight in US recipes (ounces, pounds) rather than volume. These convert directly without needing density figures: 1 oz = 28.35g, 1 lb = 453.6g. Use the Weight Converter for quick conversions of any amount.
Why Weight Is More Reliable Than Volume
If you're converting a recipe to metric anyway, this is a good opportunity to switch to weighing ingredients entirely rather than using cup measurements. Weight is more precise — a cup of flour can vary by 20-25g depending on how it's scooped, but 125g of flour is always 125g. Most professional and European bakers weigh ingredients for this reason. If you have a kitchen scale, converting a recipe to grams once means you'll get consistent results every time you make it.
Frequently Asked Questions
Can I just use one conversion factor for the whole recipe?
No. Each ingredient has a different density, so "1 cup" represents a different gram weight depending on whether it's flour, sugar, butter, or liquid. Using a single multiplier for an entire recipe will throw off the ratios between ingredients. Convert each ingredient individually using its specific weight-per-cup.
What's the easiest way to convert an entire recipe at once?
Go ingredient by ingredient using a cups-to-grams reference for each one, rather than trying to do mental math for the whole list at once. Write the gram amount next to each original measurement so you can double-check your converted recipe before baking. For volume measurements like tablespoons and teaspoons that don't need ingredient-specific conversion (most liquids, spices), a simple multiplier (1 tbsp = 15ml) works fine.
Do I need to convert teaspoons and tablespoons to metric too?
For small amounts like spices, leavening agents, and extracts, most metric recipes still use teaspoons and tablespoons, or give the equivalent in milliliters (1 tsp ≈ 5ml, 1 tbsp ≈ 15ml). Full gram conversion for tiny amounts isn't usually necessary unless precision really matters, like in professional baking.
Why do my converted metric recipes still come out different?
Beyond ingredient measurements, oven calibration, altitude, and humidity all affect baking results and aren't something a unit conversion accounts for. If a converted recipe consistently underperforms, double-check the gram weights against a reliable source and consider that oven temperature accuracy varies between US and international ovens even at the "same" converted setting.