Boil-Off and Dilution Gravity Calculatorv1.0.0

This calculator helps brewers adjust their wort volume and gravity on brew day. It uses the principle that the total amount of dissolved sugar in wort remains constant during dilution or concentration. The core relationship is: Volume 1 x Gravity Points 1 = Volume 2 x Gravity Points 2, where gravity points equal the specific gravity minus 1.000 multiplied by 1000. Two calculation modes address different scenarios you may encounter during your brew session.

• To find a new volume when you know your target gravity, use the first calculator section labeled Find New Volume (Target Gravity Known). Enter your current Wort Volume, select the appropriate Volume Unit (gallons, liters, or quarts), enter your Current Gravity as a specific gravity value such as 1.050, and enter your Desired Gravity. The calculator returns the new volume required and the volume difference.
• To find the resulting gravity when you know your target volume, use the second calculator section labeled Find New Gravity (Target Volume Known). Enter your current Wort Volume and Current Gravity, then enter the Target Volume you plan to reach. The calculator returns the resulting gravity and the gravity point difference.
• If the result indicates a positive volume difference (new volume is larger than current volume), add clean water to dilute your wort down to the target gravity. Use bottled spring water or pre-treated water free of chlorine and contaminants.
• If the result indicates a negative volume difference (new volume is smaller than current volume), continue boiling to evaporate water and concentrate the wort up to the target gravity. Adjust your late hop addition timing when extending the boil.
• Open Settings to adjust decimal precision for volume and gravity outputs. Enable Show step-by-step formula derivation to see the complete calculation breakdown with substituted values.
• All gravity values use standard specific gravity (SG) format. Enter values such as 1.048, 1.060, or 1.072. The calculator accepts fractions, mixed numbers, and decimal input in all numeric fields.
• All inputs persist automatically between sessions using local storage. Use the Reset button to clear saved values and restore defaults for each calculator section independently.

Brewers at every experience level encounter situations where the pre-boil or post-boil gravity does not match the recipe target. This calculator provides quick, accurate adjustments so you can correct course without guesswork. Below are common scenarios where this tool proves valuable.

• Homebrewing: After mashing and lautering, your pre-boil gravity reads 1.055 but the recipe calls for a post-boil original gravity of 1.052. Enter your current volume and gravity to find exactly how much water to add rather than overshooting the dilution.
• All-Grain Brewing: Your boil-off rate varies between brew sessions due to ambient temperature or kettle geometry. Use the target volume mode to determine your resulting gravity after boiling down to a known volume, then decide whether additional boiling or dilution is needed.
• Extract Brewing: After dissolving malt extract, your gravity reading is higher than expected because you added less water than planned. Calculate the exact volume of water needed to reach the target gravity without overshooting.
• High-Gravity Brewing: When brewing strong ales or barleywines with original gravities above 1.080, small volume miscalculations create large gravity errors. Use this calculator to fine-tune the relationship between your actual volume and the gravity target.
• Brew Day Troubleshooting: Poor mash efficiency resulted in a lower-than-expected pre-boil gravity of 1.038 instead of 1.045. Determine how much extra boiling time is needed to concentrate the wort, or decide whether to add dry malt extract instead.
• Recipe Scaling: When scaling a 5-gallon recipe to a 10-gallon batch, use the calculator to verify that your collected wort volume and gravity align with the scaled targets before committing to the full boil.
• Competition Brewing: Hitting exact style parameters matters for competition entries. Use both calculator modes to verify pre-boil and post-boil gravity targets are achievable from your measured values, ensuring your finished beer falls within the style guidelines.