A small brown deck between a house, a hedge and a gravel border.
Illustrative ownership context. Appearance is not a service-life prediction; costs and replacement events come from the scenario inputs.Choose one dollar basis
DeckLifecycle uses today's-dollar amounts paired with a real discount rate. Think of each future allowance as the cost of its stated scope expressed in the purchasing power of your chosen reference date. Record that date near the input sources. If you copy a future nominal estimate from another worksheet, do not silently place it beside today's-dollar amounts. Ask how the estimate was prepared and whether general inflation is already included before using it in this comparison.
Separate inflation from discounting
A real rate excludes general inflation; a nominal rate includes it. Present value and inflation adjustment answer different questions. Today's-dollar inputs can still be discounted for timing. The general relationship is 1 + nominal rate = (1 + real rate) × (1 + inflation rate). This relationship is an explanation of consistency, not a request to predict inflation for this tool. The calculator does not provide a nominal cash-flow mode or a separate inflation forecast field.
Make a clear input note
Write a brief convention beside your scenario: all amounts expressed in today's dollars as of this date, with the stated real rate. Then identify any allowance whose scope or basis remains uncertain. If a quote is dated differently, keep that date visible rather than pretending all source documents were prepared together. A scenario refresh can replace outdated assumptions with new ones. Maintain the earlier run so you can distinguish a changed input from a changed decision horizon or a new discount-rate choice.
Hypothetical consistency check
A $1,000 allowance in today's dollars remains a $1,000 input when scheduled for year five in this tool. It is then discounted using the selected real rate. In a separate nominal worksheet, a hypothetical two percent annual inflation assumption would make that bill about $1,104.08. Importing the inflated bill unchanged would mix conventions.
Common questions
Should I enter my bank's advertised interest rate?
Not automatically. An advertised nominal rate is not the same as a real rate. The correct input depends on the consistent scenario convention you intend to use.
Does today's-dollar modeling predict flat future invoices?
No. It fixes the unit of comparison. Actual future invoices may differ because of inflation, changed scope, market conditions, and other factors.
Evidence & limits
Reviewed September 13, 2026. Sources support their stated technical principles; this site's workflows and hypothetical examples are not product tests, supplier approvals or independently reviewed project records.