🌍 Metric to Imperial Recipe Converter

Why One Measurement System Was Never Going to Be Enough

Recipes don't respect borders. A brilliant chocolate tart from a French patisserie cookbook asks for 250g of butter and a 200°C oven. Your American measuring cups and an oven dial marked in Fahrenheit sit there looking unhelpful. Meanwhile, your British relative has just emailed a beloved family pie recipe that calls for half a cup of golden syrup and 375°F — and you own only a kitchen scale. This friction between metric and imperial measurements is one of the most genuinely annoying parts of cooking across cultures, and it comes up constantly.

The good news: converting between the two systems is entirely learnable, and once you understand the logic behind the numbers, you'll start seeing the conversions almost automatically as you read a recipe.

Weights: Grams, Ounces, and When to Use Each

Weight is the most reliable way to measure ingredients, and professional bakers on both sides of the Atlantic have started agreeing on this. The difference is just which unit they trust.

The core relationship to memorise: 1 ounce equals 28.35 grams. That means 100g works out to roughly 3.5 ounces, and 500g is a little over 17.6 ounces — or about 1 pound 1.6 ounces. For most kitchen purposes, rounding 500g to 1lb 2oz is perfectly acceptable, particularly for bread doughs, pastry, and anything that doesn't require jeweller-level precision.

Kilograms appear more in European and Australian recipes for larger quantities. One kilogram equals 2.205 pounds, so a 1.5kg roast becomes roughly 3 pounds 5 ounces. If a recipe says "1.2kg chicken," calling it 2 lb 10 oz is accurate enough — your oven won't care about a 5g margin.

Going the other direction, ounces back to grams: multiply by 28.35. A quarter-pound of butter (4 oz) is 113g, which explains why many American recipes call for a "stick" of butter (also 4 oz, 113g) — and why European equivalent recipes specify 100g or 115g interchangeably.

Volumes: The Cup Problem and How to Solve It

Volume is where the real confusion lives, because the cup — that cheerfully imprecise American measurement — has no direct metric equivalent that fits neatly on a measuring jug. One US cup is 236.6ml, which rounds to 237ml. Practically, 240ml is close enough for liquid measurements like milk, water, or oil.

The tablespoon and teaspoon are actually more consistent than people think: 1 tablespoon equals 14.79ml (usually rounded to 15ml), and 1 teaspoon equals 4.93ml (rounded to 5ml). If a recipe calls for 2 teaspoons of vanilla extract, you're using 10ml — easy enough to measure with most metric measuring spoons.

Millilitres to cups: divide by 237. So 500ml of stock is about 2.1 cups — in practice you'd use 2 cups plus a splash. For 1 litre, that's 4.23 cups, commonly written as 4¼ cups in recipe books.

Fluid ounces trip people up because the US and UK versions differ slightly (US fl oz = 29.57ml; UK fl oz = 28.41ml). Most recipe databases now use the US standard, and for home cooking the ~4% difference between them won't affect your dish.

Temperatures: The One That Catches Everyone

The Celsius-to-Fahrenheit formula — multiply by 9, divide by 5, add 32 — sounds like a maths test rather than a cooking instruction. The shortcut most cooks use: double the Celsius temperature and add 30. It's not precise, but 180°C becomes "360 + 30 = 390" when the actual answer is 356°F. That's close enough for most situations, though for delicate work like tempering chocolate or making caramel you want the accurate figure.

The temperatures that come up constantly in baking:

• 160°C = 320°F (slow bake, custards, cheesecakes)
• 175°C = 347°F — nearly always written as 350°F in American recipes
• 180°C = 356°F — the single most common baking temperature worldwide
• 200°C = 392°F — hot roasting, bread crusts, pizza
• 220°C = 428°F — very hot, blast roasting, puff pastry

Fan-assisted (convection) ovens run hotter than the temperature you set, usually by about 20°C or 25°F. If your European recipe says 180°C fan, set a conventional oven to 200°C (or 390°F on the American scale). British recipes often include both in brackets, but online conversions rarely do — worth keeping in mind.

Working With Mixed Recipes

Some recipes — especially those adapted for international food sites — mix systems freely. You might see "200g flour, 1 cup milk, bake at 180°C." Rather than converting ingredient by ingredient, paste the whole thing into a tool that handles all unit types at once. This matters more than it sounds: converting weights but leaving temperatures in the wrong unit is exactly the kind of partial error that results in a burnt cake or underbaked pastry.

When a recipe conversion feels slightly off — like 170g of butter being asked to stand in for 6 ounces — remember that ingredient density matters. Volume-to-weight relationships change depending on whether flour is sifted, how tightly packed brown sugar is, and how you measured. This is why weight measurements (grams and ounces) are more trustworthy than volume ones for dry ingredients. A baker writing "1 cup of flour" might mean anywhere between 120g and 150g depending on their scooping technique. When you see "200g flour," there is no ambiguity.

A Quick Reference Cheat Sheet

For regular reference while cooking, a few numbers are worth knowing by heart:

• 100g ≈ 3½ oz
• 250g ≈ 9 oz (just under ½ lb)
• 500g ≈ 1 lb 2 oz
• 1 cup = 237ml
• 1 tbsp = 15ml | 1 tsp = 5ml
• 180°C = 356°F (call it 350°F)
• 200°C = 392°F (call it 400°F)

Rounding Sensibly in the Kitchen

A recipe calling for 113g of butter will become 4oz on conversion — and 4oz is exactly one stick of butter in the US. That's a clean, useful result. But 85ml of cream converting to 2.87 fl oz is not clean, and measuring 2.87 fl oz is genuinely impossible. Here, rounding to 3 fl oz (about 90ml) is the right call. A 6% difference in cream quantity will not ruin your sauce.

The situations where precision genuinely matters are: bread recipes (hydration percentage affects texture significantly), pastry (fat-to-flour ratios are critical), and anything involving chemical leavening like baking soda or baking powder. For stews, soups, and most savoury cooking, the margin for error is much wider.

Converting a recipe needn't mean copying it out by hand with a calculator open. Paste the whole text, choose your direction, and get a ready-to-cook version — one that speaks your oven's language.