Examples
Examples
Try the starting example
- Build upfront cost ($)
- 500
- Buy upfront cost ($)
- 0
- Build costs in periods 1,2,… ($)
- 100,100,100,100,100
- Buy costs in periods 1,2,… ($)
- 200,200,200,200,200
- Discount rate per supplied period (%)
- 10
- Discounted total build cost ($)
- $879.08
- Discounted total buy cost ($)
- $758.16
- Build minus buy discounted cost ($)
- $120.92
- First period where cumulative discounted build cost ≤ buy
- None in horizon
Try another scenario
- Build upfront cost ($)
- 300
- Buy upfront cost ($)
- 0
- Build costs in periods 1,2,… ($)
- 100,100,100,100,100
- Buy costs in periods 1,2,… ($)
- 200,200,200,200,200
- Discount rate per supplied period (%)
- 0
- Discounted total build cost ($)
- $800.00
- Discounted total buy cost ($)
- $1,000.00
- Build minus buy discounted cost ($)
- -$200.00
- First period where cumulative discounted build cost ≤ buy
- 3
Calculation method
Calculation method
Discounted total build cost ($)
Build upfront + sum(build period cost/(1+rate)^period).
Discounted total buy cost ($)
Buy upfront + sum(buy period cost/(1+rate)^period).
Build minus buy discounted cost ($)
Build NPV cost−buy NPV cost.
First period where cumulative discounted build cost ≤ buy
Check the upfront comparison at period 0, then cumulative discounted costs after each supplied period; report None in horizon if no crossing occurs.
Symbols and units
- a
- Build upfront cost ($)
- b
- Buy upfront cost ($)
- c
- Build costs in periods 1,2,… ($)
- d
- Buy costs in periods 1,2,… ($)
- e
- Discount rate per supplied period (%)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
sum(list) adds all entries in the list.
Assumptions & limits
Assumptions & limits
- Compares supplied costs in one currency and equal periods. Include migration costs or credits in their appropriate period inputs; negative period values represent entered credits. No tax, financing, changing usage or live vendor prices are inferred.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
OpenStax: arithmetic and geometry ↗
Background reading; this does not imply endorsement or independent review of SumFizz.