Lighting project rate of return calculator

Solve the present-value equality for i when annual savings are level.

C_{\text{initial}} = \frac{S_{\text{net}} \times \left[1 - \left(1 + i\right)^{-n}\right]}{i}

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Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

C_{\text{initial}} = \frac{7400 \times \left[1 - \left(1 + 0.09\right)^{-12}\right]}{0.09} \approx 52{,}989

Symbol	Meaning	Unit
$C_{\text{initial}}$	incremental initial investment	$
$S_{\text{net}}$	level annual incremental savings	$/yr
$i$	rate of return solved iteratively	1/yr
$n$	project life	yr

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.