Refractometer
The Refractometer tool converts Brix readings to specific gravity and corrects for alcohol presence during fermentation.
How to Use
Pre-Fermentation (No Alcohol)
Take Reading - Place 2-3 drops on refractometer
Enter Brix Value - Read at blue/white boundary
Get SG Conversion - Direct conversion displayed
During/After Fermentation (With Alcohol)
Enter Original Gravity - Your OG before fermentation
Enter Current Brix - Current refractometer reading
Get Corrected SG - Accounts for alcohol presence
About Refractometers
Refractometers measure the refractive index of a liquid to determine sugar content. They require only a few drops of liquid, making them ideal for taking readings during the brewing process without wasting wort.
Advantages
Small sample size: Only 2-3 drops needed
Quick readings: Instant results
Temperature compensation: ATC (Automatic Temperature Compensation) models available
Durable: No fragile glass like hydrometers
Portable: Easy to carry and use
Limitations
Alcohol affects readings: Requires correction during/after fermentation
Calibration needed: Must be calibrated regularly
Learning curve: Reading scale takes practice
Not for FG alone: Need OG to calculate fermented readings
Types of Measurements
Pre-Fermentation (Wort Only)
Simple Brix to SG conversion when no alcohol is present:
Direct conversion using standard formula
Most accurate refractometer use case
No correction factor needed
During/After Fermentation
Complex calculation when alcohol is present:
Requires original gravity (OG) value
Uses correction formulas for alcohol
Less accurate than hydrometer for FG
Calibration and Correction
Wort Correction Factor
Most refractometers are calibrated for sucrose (table sugar), but wort contains maltose and other sugars.
Typical Correction Factors:
1.04: Most common default
1.02-1.06: Typical range
Determine yours experimentally
Finding Your Correction Factor
Measure same wort with both refractometer and hydrometer
Divide hydrometer SG by refractometer SG
Repeat for multiple worts
Average the results
Temperature Compensation
ATC Models: Automatic compensation 10-30°C (50-86°F)
Non-ATC: Must cool sample to 20°C (68°F)
Best Practice: Let sample reach room temperature
Common Calculations
Brix to Specific Gravity
Formula: SG = 1 + (Brix / (258.6 - (Brix * 0.88)))
Example Conversions
10 Brix = 1.040 SG
12 Brix = 1.048 SG
15 Brix = 1.061 SG
20 Brix = 1.083 SG
Alcohol Presence Correction
When alcohol is present, the refractometer reading is affected. The tool uses complex formulas to correct for this.
Best Practices
Taking Readings
Clean the Plate
Use distilled water
Dry with soft cloth
No scratches or residue
Sample Preparation
Mix wort thoroughly
Let sample settle
Avoid foam/bubbles
Consistent Technique
Same light source
Same viewing angle
Multiple readings
Maintenance
Clean after each use
Store in case
Check calibration weekly
Avoid harsh chemicals
Comparing with Hydrometers
When to Use Refractometer
Pre-fermentation readings
Small sample volumes
Quick spot checks
Field measurements
When to Use Hydrometer
Final gravity determination
Most accurate FG
Large sample available
No calculations needed
Troubleshooting
Fuzzy/Unclear Reading
Clean the plates
Check for scratches
Adjust focus ring
Better light source
Inconsistent Readings
Temperature not stable
Calibration drift
Dirty optics
Sample not mixed
Doesn't Match Hydrometer
Check correction factor
Verify calibration
Account for temperature
Consider alcohol presence
Tips
Calibrate with distilled water regularly
Let samples reach room temperature
Clean and dry after each use
Use hydrometer for final gravity for best accuracy
Using with Brewfather
Convert Brix readings to SG for consistent record keeping
The tool remembers your last entered values
Use converted values when logging batch data
Track patterns across your brews for better predictions
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