Why this guide matters
The familiar 20C reduction is useful, but convection changes surface heating enough that recipe type and browning sensitivity still need human judgment.
- - Use the fan reduction as a baseline, not a universal law.
- - Delicate and high-sugar bakes often need extra caution.
- - Earlier doneness checks are usually more valuable than aggressive temperature cuts.
Quick checklist
- Set the converted temperature conservatively.
- Check browning and set earlier than usual.
- Record what your own oven needed so the next conversion is faster.
The 20°C baseline
For many recipes, fan settings run around 20°C lower than conventional settings.
In Fahrenheit terms, a 25°F reduction is a common equivalent rule of thumb.
When to adjust beyond the baseline
High-sugar glazes, delicate cakes, and thin bakes can brown faster under fan airflow.
In these cases, monitor color and doneness earlier than the recipe states.
Keep decisions practical
Use conversion as a starting point, then tune based on observed browning and internal doneness.
Avoid chasing exact decimals; practical setpoints and validation are more reliable.
Step-by-Step
- Identify original recipe temperature scale.
- Apply baseline fan/conventional offset (about 20°C or 25°F).
- Start checking doneness earlier than the original timing.
- Adjust subsequent batches from observed browning and center set.
FAQ
Is fan always 20°C lower?
It is a strong baseline but not absolute for every recipe.
Does fan always cook faster?
Often, but not uniformly across all pan sizes and batters.
Should I change both time and temp?
Typically yes: modest temp adjustment plus earlier checks.
Do old recipes assume non-fan ovens?
Most legacy recipes were written for conventional ovens.