Why You Should Weigh Sourdough Ingredients Instead of Measuring by Cup

If you're still scooping flour with cups, you're guessing. A cup of flour can weigh anywhere from 110g to 160g depending on how packed it is. For sourdough, that variability ruins consistency.

Why volume measurements fail

Flour compresses. Scoop it out of a bag and you can compress it 30%. Sift it first and you have less. Tap the cup and you have more.

Try this: scoop 1 cup of flour three different ways and weigh each.

• Loosely scooped: ~120g
• Spoon and level: ~125g
• Scooped and tapped: ~155g

That's a 30% spread on the same "1 cup" measurement.

What that means for your sourdough

A recipe at 70% hydration with 500g flour needs 350g water.

If you actually used 600g flour because you packed your cups, your hydration drops to 58%. You'll get a tight, dense dough that won't open up.

If you used 420g flour because you under-scooped, your hydration jumps to 83%. You'll get a slack, hard-to-handle dough.

Either way, the recipe doesn't behave the way it should — and you'll think you did something wrong.

What you need

A digital kitchen scale with:

• Capacity of at least 5kg (you'll be weighing entire dough batches)
• 1g resolution
• Tare button (so you can zero out your bowl)

A decent scale costs $15–30. It's the cheapest upgrade with the biggest payoff in sourdough.

How weighing changes the workflow

Instead of:

4 cups flour, 1.5 cups water, 1 tsp salt

You read:

500g flour, 360g water, 10g salt

And you place the bowl on the scale, tare to zero, add flour until 500g, tare again, add water until 360g, tare, add salt until 10g. One bowl, one cleanup, exact measurements every time.

Other ingredients to weigh

Salt — 1 tsp can vary from 4g (kosher) to 7g (table). Always weigh.

Starter — 100g active starter is consistent. "1/2 cup starter" depends on how much it's risen.

Honey, butter, milk — all benefit from weight measurements.

What you don't need to weigh

Yeast (in non-sourdough recipes) — usually small enough that volume is fine.

Spices — small enough not to matter.

Garnishes and toppings — taste, not weight.

Baker's percentages become possible

Once you weigh, you can use baker's percentages — flour is 100%, everything else is a percentage of flour weight. Suddenly:

• Hydration is calculable: water/flour × 100
• Recipes are scalable: change flour weight, recalculate
• Kitchens become consistent

You can't do baker's percentages with cups.

The transition

If your current recipes are in cups, convert them once. Weigh out what your normal "1 cup" is and write down the gram weight. Use that going forward.

After two weeks of weighing, going back to cups will feel like driving without GPS.

A note on metric vs. imperial

Sourdough is much easier in metric (grams). Imperial (ounces) works, but the math is harder. If your scale toggles between units, set it to grams once and don't switch back.

You'll be doing percentages and ratios constantly. Grams make the arithmetic almost mental.