Soil pH Adjustment Calculator
Calculate how much lime or sulfur to add to adjust your soil pH.
Enter current pH, target pH, soil type, and area for accurate amendment amounts.
Soil Amendment Needed
Soil pH adjustment requires adding lime (to raise pH) or elemental sulfur (to lower pH). The amount depends on soil type because clay soils have higher buffering capacity.
To raise pH (add lime):
Approximate ground limestone (lbs per 1,000 sq ft) to raise pH by 1 point:
- Sandy soil: 25 lbs (11 kg per 100 m²)
- Loam soil: 50 lbs (23 kg per 100 m²)
- Clay soil: 75 lbs (34 kg per 100 m²)
To lower pH (add elemental sulfur):
Approximate sulfur (lbs per 1,000 sq ft) to lower pH by 1 point:
- Sandy soil: 10 lbs (4.5 kg per 100 m²)
- Loam soil: 15 lbs (6.8 kg per 100 m²)
- Clay soil: 25 lbs (11 kg per 100 m²)
Ideal pH ranges by plant type:
- Most vegetables: 6.0–7.0
- Blueberries: 4.5–5.5
- Azaleas/Rhododendrons: 4.5–6.0
- Lawns (most grasses): 6.0–7.0
- Roses: 6.0–6.5
Tips:
- Apply lime in fall for best results (takes 2–3 months to work)
- Never apply more than 50 lbs per 1,000 sq ft at once
- Retest soil after 3 months
- Pelletized lime is easier to spread than powder