This glossary defines every term used across the conversion calculators and charts on this site. Each entry gives the canonical term, its definition, and the synonyms treated as equivalent.
The site uses one term per concept throughout. Where a widely used synonym exists, it is listed here and mapped to the canonical form.
Appliance terms
Air fryer — A compact countertop convection oven that circulates heated air at high velocity around food held in a perforated basket or on a rack. Synonyms: airfryer, air-fryer.
Conventional oven — An oven that heats by radiant elements without a fan, so the air inside stays largely still. Synonyms accepted: regular oven, standard oven, still-air oven. Not a synonym for convection oven.
Convection oven — An oven with a fan that circulates heated air. Mechanically the same category as an air fryer, at lower fan speed and larger cavity volume. Synonym: fan-assisted oven.
Fan oven — The British and Australian term for a convection oven. Recipes give fan temperatures roughly 20°C below the conventional equivalent. Synonym: fan-forced oven (Australia).
Air fryer oven — An oven-form air fryer with racks rather than a basket, holding roughly a small sheet pan. Synonym: air fryer toaster oven.
Basket capacity — The stated internal volume of an air fryer basket, in quarts or litres. Distinct from practical batch, which is the maximum quantity that still allows air to circulate.
Conversion terms
Air fryer conversion — Restating cooking instructions written for one appliance so they produce the same result in another.
Temperature reduction — The amount subtracted from the source appliance’s temperature. 25°F (15°C) from a conventional oven; 10°F (5°C) from a convection oven.
Time factor — The multiplier applied to the source appliance’s cooking time. 0.8 from a conventional oven; its reciprocal 1.25 in the reverse direction.
The 25°F (-5°C) and 20% rule — The standard conventional-oven-to-air-fryer conversion, expressed as its two adjustments.
Boundary layer — The thin film of cooler, moisture-laden air that clings to food in still air and slows heat transfer into it. Forced convection strips it away, which is the mechanism the entire conversion compensates for.
Practical batch — The maximum quantity of a given food that fits an air fryer basket in a single loose layer with visible gaps. Always lower than the stated capacity implies.
Recovery — How quickly an air fryer restores cavity temperature after cold food absorbs heat from it. Governed largely by wattage.
Unit terms
Gas mark — The UK scale for gas oven temperatures. Gas mark 4 is 180°C conventional; gas mark 6 is 200°C.
Fahrenheit to Celsius — Subtract 32, then multiply by 5/9. As a temperature difference, 25°F (15°C) equals 13.9°C; the site uses 15°C because air fryers dial in 5°C steps.
Wattage — The electrical power an air fryer draws, between roughly 800W and 2,200W. Affects converted time, not converted temperature.
Doneness terms
Internal temperature — The temperature at the thickest part of the food, and the only reliable doneness test for proteins. Poultry 165°F (74°C); whole cuts of pork, beef and fish 145°F (63°C); ground meat 160°F (71°C).
Carryover — The continued rise in internal temperature after food leaves the heat, typically 3–5°F (3°C) for a small cut and more for a large one.
Rest — The interval after cooking during which juices redistribute and carryover completes. Three minutes for pork chops, five for steak and chicken breast, fifteen for a whole chicken.
Related conversions and adjacent topics
Temperature and time convert together, never separately. The same rule set covers every appliance pair on this site, and the methodology page sets out where it comes from and the seven conditions under which it stops holding.
Every figure above is built into the oven to air fryer conversion calculator, which applies both adjustments together so you do not have to work them out separately.
Frequently asked questions
Is an air fryer a convection oven?
It is the same category of appliance — heating element plus fan — at higher fan speed and much smaller cavity volume.
Is a fan oven the same as a convection oven?
Yes. Fan oven is the British and Australian term for the same appliance.
What is the difference between capacity and practical batch?
Capacity is the stated internal volume; practical batch is the quantity that still allows air to circulate, which is consistently lower.