Yeast scales linearly for most home recipes: double the recipe, double the yeast. At three times or more, large dough masses retain heat from fermentation, which speeds the process — reduce yeast by 10–15% and watch the dough visually rather than following the original time. Salt stays proportional at 1.8–2% of flour weight at any scale.
Use the recipe scaler to convert quantities and the yeast converter to switch between yeast types.
Why yeast and salt are different from other scaling ingredients
Flour, water, and fat scale exactly. Yeast and salt work differently because they control a living biological process (fermentation), and the way heat distributes through a large dough mass is not the same as in a small one.
Yeast: Fermentation generates heat. A small 500 g dough ball loses heat to its environment. A large 2 kg dough mass retains that heat at its center, creating a warmer environment for the yeast — which speeds up fermentation unpredictably.
Salt: Salt is a yeast inhibitor. In bread, salt slows yeast activity, strengthens gluten, and controls fermentation timing. At any scale, the salt-to-flour ratio must stay constant to maintain the same fermentation rate and flavor.
Salt scaling by flour weight
Professional bakers express salt as a percentage of flour by weight (baker’s percentage). Use this table at any batch size:
| Salt % | Grams per 100 g flour | Per 500 g flour | Per 1 kg flour |
|---|---|---|---|
| 1.5% | 1.5 g | 7.5 g | 15 g |
| 1.8% | 1.8 g | 9 g | 18 g |
| 2.0% | 2 g | 10 g | 20 g |
| 2.2% | 2.2 g | 11 g | 22 g |
Most recipes land between 1.8% and 2.2%. A French baguette is typically 2%; a sourdough often 2–2.2%; a ciabatta sometimes 1.8%.
Converting volume salt to weight
Since salt type has a huge impact on weight per tablespoon, always weigh salt when scaling bread:
| Salt type | 1 tsp weight | 1 tbsp weight |
|---|---|---|
| Table salt (iodized or plain) | 6 g | 18 g |
| Morton’s kosher salt | 5.3 g | 16 g |
| Diamond Crystal kosher salt | 2.7 g | 8 g |
| Fine sea salt | ~5–6 g | ~15–18 g |
Source: King Arthur Baking ingredient weight chart
If a recipe calls for “1 tablespoon kosher salt” and you switch from Diamond Crystal to Morton’s, you’d add twice the salt. This is why professional recipes always specify weight and salt type.
Yeast scaling guidelines
| Batch size | Yeast adjustment | Notes |
|---|---|---|
| 0.5x (half recipe) | 0.5x yeast | Fine — scale directly |
| 1x (original) | 1x yeast | Baseline |
| 2x | 2x yeast | Fine — scale directly |
| 3x | 2.7x–2.8x yeast | Reduce by ~10% |
| 4x | 3.4x–3.6x yeast | Reduce by ~10–15% |
| 5x+ | 4x–4.2x yeast | Reduce by ~15–20%; monitor closely |
At large scale, watch for the dough to reach the same visual/tactile benchmarks (doubled in size, correct jiggle) rather than following the original timing. Large batches can take less time than the recipe states.
Yeast types and scaling
The yeast converter handles exact conversions, but the key rules are:
| To switch from | To | Multiply by |
|---|---|---|
| Active dry | Instant | 0.75 (use 25% less) |
| Instant | Active dry | 1.33 (use 33% more) |
| Fresh yeast | Instant | 0.33 (use 1/3 the amount) |
| Fresh yeast | Active dry | 0.5 |
Fresh yeast is about 3x more perishable and less concentrated than instant yeast. Most US home bakers use instant dry yeast (also sold as rapid-rise or bread machine yeast).
Worked example: scaling a basic white bread recipe
Original (makes 1 loaf):
- 500 g bread flour
- 325 g water (65% hydration)
- 10 g salt (2% of flour)
- 5 g instant yeast (1% of flour)
Scaled to 3 loaves (3x):
- 1500 g bread flour
- 975 g water
- 30 g salt (same 2% ratio — no adjustment needed)
- 13.5 g instant yeast (0.9% of flour — reduced by 10%)
Fermentation note: With 3 loaves’ worth of dough in one mass, expect bulk fermentation to finish 10–20% faster than the original single-loaf time. Divide and shape earlier rather than later.
Scaling preferments and sourdough starters
When a bread recipe includes a preferment (poolish, biga, levain, or sourdough starter), scaling works differently from straight doughs.
For a poolish or biga: These are typically expressed as a percentage of total flour. A recipe using a 20% poolish (20 g of the total flour pre-fermented with water and a tiny amount of yeast) scales in proportion with total flour weight. If you double the recipe, double the poolish quantities. The yeast in the poolish is already small — typically 0.1–0.2% of flour. Doubling it is fine.
For a sourdough starter/levain: Most sourdough recipes call for a levain (young starter) at 15–25% of total flour by weight (baker’s percentage). This scales linearly with flour. If your original recipe calls for 150 g levain in a 500 g flour dough (30%), your doubled recipe uses 300 g levain in a 1000 g flour dough. The fermentation time stays the same because the hydration and proportion remain constant.
What changes with large sourdough batches: the starter’s temperature during fermentation. A large levain mass retains heat, so it may ripen faster than expected. Taste it — when it smells tangy and yeasty (not overly sour or alcoholic), it’s ready, regardless of the clock.
Baker’s percentage reminder: All ingredients in a bread formula can be expressed as a percentage of flour weight, making scaling precise and independent of batch size. The baker’s percentage calculator handles the math for any batch size.
Mixing salt late (autolyse)
A note relevant to scaling: many professional recipes use an autolyse step where flour and water mix without salt for 20–60 minutes before salt is added. Scaling doesn’t change this timing. However, in larger batches, the salt needs more mixing time to fully incorporate after addition — plan for an extra 2–3 minutes of kneading per additional kilogram of dough. Under-mixed salt creates uneven fermentation rates across the dough mass.
High-altitude yeast adjustment
At altitudes above 3,500 feet, reduced air pressure causes dough to rise faster. Reduce yeast by 25% for altitudes between 3,500–6,500 feet, and by up to 50% above 7,000 feet. See high altitude baking adjustments for the full guide.