Homebrew Batch Scaling Calculator

Why Scale Homebrew Recipes?

Small-batch brewing is a fun way to test new ingredients, but once a recipe succeeds, many brewers want to make larger batches. Scaling also works in the opposite direction if you only want to brew a small test gallon before committing to a full carboy. This tool helps you adjust your ingredient list quickly and confidently so your beer tastes consistent no matter how much you produce.

Linear vs. Non-Linear Scaling

For most ingredients like water and yeast, a simple linear ratio works perfectly. If you double the volume, you double the water. However, Malt and Hops can be trickier:

• Malt & Efficiency: Larger systems often have different extraction efficiencies. If your 5-gallon cooler mash tun gets 70% efficiency but your 15-gallon automated system gets 80%, you need less grain per gallon to hit the same Original Gravity (OG). Our "Efficiency Adjustment" mode handles this.
• Hops & Utilization: Hop utilization (IBU extraction) depends on boil volume and gravity. While this calculator provides a linear scale for hops, be aware that moving from a partial boil (extract) to a full boil (all-grain) significantly increases utilization, so you might need fewer bittering hops.

Mathematical Formula

The basic scaling factor $F$ is the ratio of target volume to original volume:

$$F=\frac{V_{\mathrm{target}}}{V_{\mathrm{original}}}$$

If adjusting for efficiency, the grain scaling factor $F_{\mathrm{grain}}$ becomes:

$$F_{\mathrm{grain}}=F\times \frac{E_{\mathrm{original}}}{E_{\mathrm{target}}}$$

This ensures that if your new system is more efficient, you use proportionally less grain to achieve the same sugar content.

Common Batch Sizes

Tips for Successful Scaling

Keep detailed notes about your brew day: mash temperatures, water additions, gravity readings, and final volume. That way, if your scaled batch tastes different, you can pinpoint why. Many brewers also use brewing software to estimate IBU, color, and alcohol content. This calculator offers a quick way to adjust raw ingredient quantities, and then you can fine-tune with your preferred brewing tools.

Adjusting Boil Off and Fermentation Time

Bigger batches often have slightly different evaporation rates during the boil and may require longer chilling and fermentation periods. Keep an eye on your boil off volume when scaling up, as losing more or less water than expected changes the original gravity. Likewise, fermentation may take longer if your yeast has to work through a larger quantity of wort. Recording these variables helps you refine future batches.