Wine Residual Sugar Calculator
Calculate residual sugar (RS) in wine from specific gravity readings.
Determine wine sweetness level from grams per liter of residual sugar.
Residual sugar (RS) is the sugar remaining in a wine after fermentation is complete. It directly determines whether a wine is dry, off-dry, semi-sweet, or sweet — and it affects how the wine tastes, pairs with food, and ages.
Residual Sugar from Brix Formula:
RS (g/L) ≈ (Initial Brix − Final Brix) × 0 + Final Gravity RS
The practical formula used by winemakers:
RS (g/L) = (Final Specific Gravity − 1.000) × 1000 × 0.64
Or from finishing Brix (when using a refractometer after fermentation):
RS (g/L) ≈ Finishing Brix × 10
(Note: refractometers are less accurate post-fermentation due to alcohol interference — use a hydrometer or Clinitest for precision)
Wine sweetness classification by RS:
| Category | RS (g/L) | RS (%) |
|---|---|---|
| Bone dry | 0–1 g/L | 0–0.1% |
| Dry | 1–9 g/L | 0.1–0.9% |
| Off-dry | 9–18 g/L | 0.9–1.8% |
| Semi-sweet | 18–45 g/L | 1.8–4.5% |
| Sweet | 45–120 g/L | 4.5–12% |
| Dessert wine | 120+ g/L | 12%+ |
Worked example: Initial Brix: 24°Bx Fermentation stopped early; finishing SG: 1.020 RS = (1.020 − 1.000) × 1000 × 0.64 = 20 × 0.64 = 12.8 g/L → off-dry
Balancing sweetness with acidity: Higher RS requires higher acidity to avoid a cloying taste. German Rieslings achieve this balance naturally with high tartaric acid. The perception of sweetness drops significantly when pH is low — a 15 g/L wine at pH 3.0 tastes drier than the same RS at pH 3.5.
Stabilization: Wines with RS above 2 g/L must be stabilized (cold stabilization + potassium sorbate + sterile filtration) to prevent re-fermentation in the bottle.