📏 Homebrew Recipe Batch Size Scaler

Add your recipe's ingredients and quantities, set your original and target batch sizes, and scale every ingredient proportionally.

Original Batch Size (gal)

Target Batch Size (gal)

How the scaling is worked out

One ratio drives the whole sheet. Every ingredient row is multiplied by it and printed to two decimal places:

scale factor = target batch (gal) / original batch (gal)
new quantity = old quantity × scale factor

The page opens on a 5 gallon recipe going to 10, so the factor is 2.00x and the 10 lb of pale malt becomes 20 lb, the crystal malt 2 lb and the ounce of Cascade 2 oz. Going the other way is the same arithmetic: 5 gallons down to a 1 gallon test batch is 0.20x, which turns 10 lb of base malt into 2.00 lb and an ounce of hops into 0.20 oz.

Filling in the rows

The unit column is a label, not a conversion. Type lb, oz, g or packet and the same word comes back beside the scaled figure. Nothing is converted between units, so keep each row consistent.
Blank or non-numeric quantities count as zero and a row with no name is listed as "Untitled". Add as many rows as the recipe needs with the Add Ingredient button; Remove deletes one and recalculates.
Batch sizes must both be above zero in the same unit. The fields say gallons, but litres in both boxes give the identical factor.

Bitterness does not scale linearly. Hop utilisation falls as boil gravity rises and with kettle geometry, so a doubled hop bill in a doubled batch rarely lands on the same IBU. Scale the malt and water with this tool, then check the hops against a bitterness calculation.

Frequently asked questions

How do I scale a 5 gallon recipe to 10 gallons?

Multiply every ingredient by 2. A 10 lb, 1 lb, 1 oz recipe becomes 20 lb, 2 lb and 2 oz. Water volumes double too, but boil time stays as written.

Do I double the yeast as well?

Yeast is pitched by cell count, and cells needed rise with both volume and gravity, so doubling the batch does mean roughly double the yeast. Two fresh packets or a starter, rather than one packet stretched.

Will a scaled recipe hit the same original gravity?

Only if your efficiency holds. Larger mashes often lose a point or two of extraction and boil off a different fraction of the volume, so check the pre-boil gravity and adjust with water or a late sugar addition.