ROI Degree Calculator: calculate roi degree for students and teachers. Clear steps and worked examples.
ROI (%) = (Net return ÷ Cost) × 100
Net return = Total return − Total cost
Payback period = Cost ÷ Annual return
Example — Double glazing: Installation cost 5,000. Annual energy saving 350/yr. ROI = (350 ÷ 5,000) × 100 = 7% per year. Payback = 5,000 ÷ 350 = 14.3 years.