Group replacement windows by specification
A window order can contain several sizes, opening styles and glazing packages. This calculator handles one group of identical units using a supply price, a fitting charge and an allowance for making good around each opening. It also accepts project-wide extras, which are charged once rather than once per window. The quantity must be a positive whole number. Run the worksheet separately for each group when a house contains different specifications, and ensure shared delivery or access charges are included only once in the combined estimate.
From per-unit prices to the project total
Per-window subtotal = supply + fitting + making good; project subtotal = count × per-window subtotal + extrasThe contingency reserve is a percentage of that project subtotal. Making good can include internal trim, plaster patching, decoration and external finish repairs when those are excluded from fitting. If a turnkey quotation already covers these items, leave their separate allowance at zero to avoid doubling them. Project extras might include delivery, special access equipment or a single disposal charge. The example values are editable placeholders, with no assumption about current regional prices. Every field uses the same currency; the metric and imperial switches do not perform currency conversion because the inputs are counts and prices.
Worked order for eight matching units
Eight windows priced at 400 each cost 3,200 to supply. Fitting at 150 and making good at 50 bring each unit to 600. Eight completed openings therefore cost 4,800 before shared charges. Add project extras of 300 to obtain 5,100. A reserve of 10 percent is 510, and the displayed budget becomes 5,610 currency units. If only six of those windows are ordered, change the quantity rather than changing the rate: the shared extras remain 300 unless the supplier has issued a revised quotation. This distinction makes a partial replacement easier to compare with the full order.
Specify the opening and installation method
Supply prices should refer to the exact product, including size, frame finish, hardware and glazing. Confirm whether the installation is an insert into the existing frame or a full-frame replacement requiring additional finish work. Screens, sill repairs and disposal of old units may be separate. Measurement tolerance and ordering dimensions should come from the supplier's survey; this cost worksheet does not determine them. Choose one tax convention across all rates, as tax is not added automatically. Retain the product schedule and written installation scope alongside the result. The worksheet cannot quantify hidden rot, unusual lintel conditions or performance improvements, and it does not estimate utility savings. Update the relevant allowance when inspection findings or a specification change affects the quote.
Frequently asked questions
Can I enter different window sizes together?
Use separate calculations for separately priced groups, then combine the subtotals. A single blended price works only if it represents the actual quoted order.
Does fitting include trim repairs?
Only if the quotation says so. Enter making good separately when internal or external finishes are excluded from installation.
Will the unit switch change my currency?
No. These fields contain counts and prices, so both unit modes use the same units. The calculator never converts exchange rates.
Can I enter half a window?
No. The quantity must be a positive integer because the estimate prices complete supplied and installed window units.
Are energy savings included?
No. This page totals replacement costs from your inputs. Heating savings require product performance, building conditions and a separate energy model.
Last reviewed: 2026-10-03 · How we calculate