Sod vs seed — which is more cost-effective?

Seed is 70–85% cheaper upfront ($0.10–$0.30/sqft vs $1.50–$3.50/sqft for sod) but needs 4–10 weeks of intensive watering, weed control, and reseeding bare patches. Sod gives an instant finished lawn, requires only 2–3 weeks of careful watering before normal use, and dramatically reduces weed pressure in year 1. For a 3,000 sqft backyard: seed costs $300–$900 in materials + ~30 hours of your time over 6–10 weeks; sod costs $4,500–$10,500 fully installed. Sod is the easy choice for impatient homeowners, sloped yards (where seed washes out), and pre-resale staging. Seed wins on pure cost if you're committed to the 2-month establishment period.