Window calculators.

There are two ways to curtain a window, and they need different arithmetic. Ready-made panels come in stock widths and lengths, so the question is which size and how many. Sewn curtains start from a bolt of fixed width, so the question is how many yards. There is one calculator for each.

Buying ready-made panels

The Curtain size calculator builds the rod width from the window plus the extension on each side, multiplies it by a fullness and splits it between the panels. It then counts the stock panels that width takes, reports the fullness they really deliver, and names the stock lengths just above and just below the finished length.

Sewing from a bolt

The Curtain fabric calculator prints the cut list behind the yardage: fabric widths per panel, the cut width and cut drop with each allowance named, the waste a pattern repeat adds, and the lining. The drops are drawn on the bolt so the total can be checked by eye.

Size first, fabric second

The fabric page asks for a rod width, a fullness and a finished length, which are the figures the size page works out. Settle where the rod sits and how full the curtain should look, then carry those numbers over. Blinds and shades are not calculated here.

Replacing the windows themselves

The Window replacement cost calculator starts from a list of openings by width and height, then divides each contractor's bid by the windows and the square feet it covers. Lines one bid prices and another skips, such as removal or the permit, are flagged, and the U-factor and SHGC each bid states are checked against the ENERGY STAR criteria for your zone.