Connection between the pH and effectiveness of SO2

Molecular SO₂ is the active form against microorganisms and unwanted bacteria. The recommended level of molecular SO₂ for red wines is 0.5ppm (mg/L), for white wines is 0.8ppm (mg/L) and dessert wines is up to 1.5ppm (mg/L) . You can use this table to determine how much Free SO₂ is required to protect your wine, based on its pH. Free SO₂ over 50ppm (mg/L) can be tasted and detected in the nose.

pH	Free SO₂ needed for 0.5 ppm molecular SO₂	Free SO₂ needed for 0.8 ppm molecular SO₂	Free SO₂ needed for 1.5 ppm molecular SO₂
2.9	7	11	20
3.0	8	13	25
3.1	10	16	31
3.2	13	20	38
3.3	16	26	48
3.4	20	32	60
3.5	25	40	75
3.6	31	50	90
3.7	39	63	118
3.8	49	81	148
3.9	62	99	186
4.0	78	125	234

pH	Free SO₂ needed for 0.5 ppm molecular SO₂	Free SO₂ needed for 0.8 ppm molecular SO₂	Free SO₂ needed for 1.5 ppm molecular SO₂
2.9	7	11	20
3.0	8	13	25
3.1	10	16	31
3.2	13	20	38
3.3	16	26	48
3.4	20	32	60
3.5	25	40	75
3.6	31	50	90
3.7	39	63	118
3.8	49	81	148
3.9	62	99	186
4.0	78	125	234

pH	Free SO₂ needed for 0.5 ppm molecular SO₂	Free SO₂ needed for 0.8 ppm molecular SO₂	Free SO₂ needed for 1.5 ppm molecular SO₂
2.9	7	11	20
3.0	8	13	25
3.1	10	16	31
3.2	13	20	38
3.3	16	26	48
3.4	20	32	60
3.5	25	40	75
3.6	31	50	90
3.7	39	63	118
3.8	49	81	148
3.9	62	99	186
4.0	78	125	234

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SO2 Additions Calculators

Connection between the pH and effectiveness of SO2

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SO₂ Additions Calculators

Connection between the pH and effectiveness of SO₂

pH	Free SO₂ needed for 0.5 ppm molecular SO₂	Free SO₂ needed for 0.8 ppm molecular SO₂	Free SO₂ needed for 1.5 ppm molecular SO₂
2.9	7	11	20
3.0	8	13	25
3.1	10	16	31
3.2	13	20	38
3.3	16	26	48
3.4	20	32	60
3.5	25	40	75
3.6	31	50	90
3.7	39	63	118
3.8	49	81	148
3.9	62	99	186
4.0	78	125	234