Oven Temperature Conversions: A Complete Guide to F, C, and Gas Mark

There is a particular kind of frustration that comes from pulling a cake out of the oven only to find it gummy in the center — not because the recipe was wrong, but because the temperature was. You followed the instructions. You preheated. You timed it exactly. What you may not have done is convert the temperature correctly, and in baking, that gap between 325°F and 350°F is the difference between a tender crumb and a dense disaster.

This guide covers every temperature scale you will encounter in a modern kitchen: Fahrenheit, Celsius, and Gas Mark. It also addresses the often-ignored fan oven adjustment, a correction that recipe writers frequently forget to mention and home cooks rarely think to make.

Why Three Scales Still Exist

The persistence of three separate temperature systems is not stubbornness — it is geography and era. The United States uses Fahrenheit almost exclusively. The United Kingdom, Australia, and most of Europe work in Celsius. Gas Mark is a British system introduced in the early twentieth century when gas ovens were standardised and domestic cooks needed a simple numbered dial rather than a thermometer reading. Each system made sense in its time and place, and cookbooks from different countries still default to their native scale without apology.

The practical consequence is that a home cook with a diverse cookbook collection — say, a Nigella Lawson baking book alongside an American-published patisserie guide — will spend a meaningful portion of their kitchen life converting between all three. Knowing the formulas helps, but a well-organised reference table is faster.

The Conversion Formulas

These are the exact mathematical relationships between the three scales:

• Fahrenheit to Celsius: subtract 32, then multiply by 5/9. So 350°F becomes (350 − 32) × 5/9 = 176.7°C, rounded to 180°C.
• Celsius to Fahrenheit: multiply by 9/5, then add 32. So 200°C becomes (200 × 9/5) + 32 = 392°F, rounded to 400°F.
• Gas Mark to Celsius: multiply the Gas Mark number by 14, then add 121. Gas Mark 4 gives (4 × 14) + 121 = 177°C, again roughly 180°C.

You will notice that recipes frequently round these numbers. 176.7°C becomes 180°C in print, and 392°F becomes 400°F. Ovens themselves are rarely accurate to within 5°C, so this rounding is sensible rather than sloppy. The error introduced by rounding is almost always smaller than the natural variation within your oven.

The Complete Temperature Conversion Table

The table below covers the full range of domestic baking temperatures, from the very low temperatures used for meringues and slow-roasted garlic to the very high heat required for artisan bread and pizza.

Fan Ovens: The Adjustment Most Recipes Ignore

A conventional oven heats from elements at the top and bottom, creating natural hot and cool spots. A fan oven — called a convection oven in North America — adds a circulating fan that distributes heat more evenly and more aggressively. The result is that food cooks faster and more uniformly in a fan oven, which sounds like a clear advantage, and mostly is, except when you forget to account for it.

The standard adjustment is straightforward: reduce the stated temperature by 20°C (or 25°F) when using a fan oven, or reduce the cooking time by approximately 15 to 20 percent. Most professional bakers do both — they drop the temperature slightly and start checking 10 minutes earlier than the recipe suggests.

This matters most with delicate items. A sponge cake baked in a fan oven at the temperature intended for a conventional oven will often brown too quickly on the outside before the center has set. Choux pastry can collapse. Macarons can crack. Custards can curdle at the edges while remaining liquid in the center. None of these failures are the recipe's fault; they are the result of applying conventional-oven temperatures to a fan-driven environment.

The fan oven conversion table below recalculates the standard temperatures:

Common Baking Temperature Ranges and Why They Exist

Understanding why different foods require different temperatures is more useful than memorising numbers in isolation. The temperatures are not arbitrary — they reflect the chemistry happening inside the food.

Low Heat: 110°C–150°C (225°F–300°F)

This range is used for anything that needs to dry out or cook very gently. French meringues bake at 100°C to 120°C for an extended period — the goal is not so much to cook them as to dehydrate them, removing moisture without introducing color. Slow-roasted tomatoes, confit garlic, and custard-based dishes (crème brûlée, bread pudding) also fall here. These preparations are sensitive to even modest overheating. Custard protein sets gently below 85°C; push the oven much higher and the proteins tighten and weep.

Moderate Heat: 160°C–180°C (325°F–350°F)

This is the default range for most layer cakes, butter cakes, muffins, and loaf breads. At 175°C, the Maillard reaction — the browning reaction between amino acids and sugars — proceeds at a pace that builds flavor without outrunning the internal set of the batter. Fruitcakes bake here for extended periods; the low-to-moderate heat allows the dense fruit-laden batter to cook through without the exterior burning. Cheesecakes bake here too, often in water baths that moderate the temperature even further.

Moderately Hot: 190°C–200°C (375°F–400°F)

This is the territory of pastry. Shortcrust and puff pastry need high initial heat to create steam rapidly, which lifts the layers and cooks the fat into a flaky structure. Tarts and quiches typically start at 200°C, sometimes dropping after the initial set. Roasted vegetables and chicken pieces also live in this range — hot enough to caramelise but not so aggressive that the outside burns before the inside cooks.

Hot to Very Hot: 220°C–250°C (425°F–480°F)

Artisan bread requires an initial burst of very high heat. Professional deck ovens reach 260°C or higher; domestic ovens at their maximum setting get close enough to produce a respectable crust. Pizza follows the same logic — a Neapolitan pizza at 250°C for 8 to 10 minutes produces the slight char on the crust that distinguishes it from what comes out at 200°C. Searing meats before reducing the heat (reverse-sear or the other way around) also uses this range.

A Note on Oven Calibration

Even after you have converted a temperature correctly and applied the fan adjustment, your oven may still be running hot or cold. Oven thermostats drift over time, and many domestic ovens are inaccurate from the factory. An oven that displays 180°C may actually be running at 165°C or 195°C. A standalone oven thermometer, available for a few pounds or dollars, is one of the highest-return investments a serious home baker can make. Place it at the center of the rack you bake on most, preheat fully, and compare the reading to the dial. If there is a consistent offset — say, your oven always runs 15°C hot — you simply compensate every time you bake.

Quick Mental Shortcuts for Common Conversions

When you need a fast approximation without a table:

• Double the Celsius temperature and add 30 to get a rough Fahrenheit figure. 180°C → 360 + 30 = 390°F (actual: 356°F — close enough for most purposes).
• Subtract 30 from the Fahrenheit temperature and halve it for Celsius. 350°F → 320 ÷ 2 = 160°C (actual: 177°C — this one is less precise, better used as a sanity check than an exact conversion).
• Gas Mark multiplied by 25 gives a rough Celsius figure with 125 added: Gas 6 → 150 + 125 = 275°C. This overestimates, but the formula (Gas Mark × 14 + 121) is accurate if you have a moment to calculate.

These shortcuts fail at the extremes, so for very low or very high temperatures, use the full formula or the table above.

Final Thought

Temperature conversion is one of those kitchen skills that feels tedious until the moment it saves you. The cook who understands why 180°C and 350°F are the same number — and who knows to knock 20 degrees off that figure for a fan oven — will consistently produce better results than one following recipe temperatures blindly. The arithmetic is simple. The reward is reliable baking, every time.