How long does it take to build a Magento extension?

Typical timelines:

• Spec Audit: 1–2 days from kick-off call to delivered spec doc
• Standard Extension: 3–6 weeks — week 1 spec sign-off, weeks 2–5 build + tests, week 6 docs + handover
• Marketplace-Ready: 6–10 weeks — standard build plus Marketplace submission, EQP fixes, listing assets, demo video

Add 1–2 weeks if you want a UAT cycle with real users before sign-off.