Building wooden furniture doors
and calculating the size of door components

Build or buy

Many woodworkers "outsource" their doors - buy factory made doors for their furniture. Excellent quality doors are available from many vendors. But my choice is normally to build the doors because I can use wood from the same batch as other wood in the project (better color matching), and my volume is small - not worth the effort of placing and order and waiting for delivery.

Types of doors

The basic starting point is a raised panel door. Rails and Stiles are typically 2 inches wide, plus extra for "mouldings," so about 2 3/8 inches. Narrower is okay, but doesn't leave a lot of glue area at the corners, and may be short of room for European hinges. Wide starts to get into issues of wood expansion across the grain (where the cross-grain of the rails connects to the edge of the stiles). The floating panel can expand and shrink independent of the rails and stiles - I use space balls to absorb the expansion and keep the panel from rattling.

A Shaker door is a flat panel door, often with a simple slot (no fake mouldings) but otherwise similar to a raised panel door. If I am using a hardwood panel (bookmatched, of course!) the dimensions are similar to raised panels, including the use of space balls. If the panel is plywood or MDF (paint grade or veneered) the panel can "fill" the slot, even be glued in, to add stability to the door.

Glass doors are either made with special cutters or can be made using the rail and stile cutters for a floating panel door. After the door is complete, the back of the groove is cut out with a router (I use a climb cut and a special cutter). Most glass is glued in these days, in a bed of clear silicone glue, rather than being nailed in with a moulding strip. If you buy the glass separately, it should be slightly smaller than the opening to leave room for the adhesive.

Slab doors seem simple but are not. If they are made of plywood, they are stable, but need a very durable edge - glue on edge banding may not be sufficient for a heavily used door. If they are made of solid wood, there is risk of warping, plus the door will expand across grain - typically getting wider. With an overlap door, probably no issue, but if you have double doors, just how much room must be left between them?

Edge Treatment

The European style door has square edges. Fine, but if you want a really clear surface, with no knobs or handles, you need a slight fingerhold to open the doors. I find a 12-15 degree slope on the edge of the door is sufficient, and doesn't interfere with typical Euro hinge installation.

There are profiles that can be cut in a door edge to add character, similar to the raised panel. The cutter I use also adds a slope to the side, so handles are optional.

Some people like a simple roundover on the front and back of all door edges

Some Shaker doors are partially inset in the door frame - a 3/4 inch thick door is inset 3/8 inch deep. The groove for the inset is 3/8 inches from the edge, with 1/4 inch overlapping the frame, and 1/8 inch gap on all sides. This style door is used with face frames and special hinges that straddle the inset rabbet. These partially inset doors (and drawer fronts) are often rounded over on the outside.

Top treatment

A raised panel door doesn't have to have a straight 2 inch rail across the top - it can have a more decorative shape. A couple common designs are Roman arch (a smooth curved top, but it leaves a "pointy" area at the ends that are at risk of chip-out) and Cathedral (an arch in the center that curves back to a horizontal line at the ends).

Templates are required for the top of the floating panel as well as the rail itself... and the two templates are slightly different, since the floating panel fits into a slot in the rail. In addition a separate template is required for each door width. BUT normally the height of the pattern is the same across all the different widths of the doors. In the set of templates I use, the rails at the top are 1½ inches taller than a straight rail.

European door sizes

The European or frameless cabinet (no face frame) normally has the doors overlap the edge of the ¾ inch (19 mm) plywood cabinet sides. Therefore the simple answer for a one door Euro-style cabinet is that the door should be ¾ inch larger than the opening on each side, or the door should be 1½ inches wider and 1½ inches taller than the opening.

BUT if you have two door on a single opening, you need the ¾ inch overlap on the hinge side only - no gap, or perhaps 1/8 inch gap, between the two doors in the middle of the opening.

If two door share a single divider in the cabinet, both cannot overlay the same ¾ inch divider - each door only has 3/8 inch of the divider. Although the special "half cranked" hinges theoretically allow no space between the two doors, you may want an 1/8 inch gap, so each door only has 5/16 inch of overlap of the shared divider. It doesn't matter whether the hinge or the opening of the door is sharing that overlap, just be sure to allow 5/16 in that side of the door size. (The other side of the door may not be sharing a cabinet side or divider, so one door may have a 3/4 inch overlay on one side and a 5/16 inch on the other side.)

Spreadsheet for the calculations

Feel free to download this Excel spreadsheet to help with the calculations. First get a copy on your computer. You can click on the link to open it (it may download as read-only), then save it on your machine, or you can right click on the link and "save target as..." I saw a similar calculator available on the internet for $25 - if you would like to send me $25, feel free to do so, but this one is free. There are no macros or other programs in the spreadsheet - nothing that could harm your computer. As you receive the spreadsheet, it is set up the way I use it. You may wish to customize it for your use, as described below.

I suggest that you keep an "empty" copy, with no doors, but customized as you normally use it. Each time your get ready to use it, start Excel with the empty copy, and save it with a new file name... perhaps the name of the job. Then start entering the doors required in this new copy. As routinely used, the variable fields - dimensions, counts, styles - are not locked, but the formulas are protected so that they are not accidentally changed.

Customizing the spreadsheet

The spreadsheet should work with almost any version of Excel, and perhaps with competing spreadsheet programs. The directions here assume Microsoft Excel on Windows. Two separate steps are required to customize the sheet.

First you have to turn off "protection," to allow you to change some of the values that never change in routine use. Look under the tools menu for Protection, and select "Unprotect the sheet." Remember where this is, because when you are done, you will want to again protect the sheet, no password required.

You may notice that the low number rows aren't visible - the constants that you may want to customize are in those hidden rows. To see them "unfreeze panes" under the Windows menu. The screen is still split, but you can scroll the upper half to see and change those values. When you are done scroll the top part so the titles are visible, and "freeze panes." The protection and frozen panes should make it easier to use, and you don't accidentally change any of the formulas.

Rail/stile width, not counting the width of the simulated "moulding," is set in cell P1. Default is 2 inches, which I like in most cases. It is wide enough to provide support and handle hinges, but not so wide that wood movement becomes a problem.

If you choose a curved top, such as Roman or Cathedral top, how much extra width is required in the top rail? With the templates I use, the extra is 1 1/2 inches, in cell P2

Moulding width is set in cell P3. Most rail/stile cutters cut a simulated 3/8 inch wide moulding in the sides of the rail and stile. Some people would call the overall rail and stile width 2 3/8 inches, but the calculations in this sheet are made based on rail width and moulding width entered separately.

Depth of slot - cell P4. Most of the rail and stile cutters I have owned cut a slot equal to the depth of the moulding, but I recently bought a "premium" cutter that makes a deeper slot - 1/2 inch rather than 3/8 - for greater strength as the rails and stiles are glued together. This means the wood to cut the rails need to be 1/8 inch longer on each end, or 1/4 inch longer overall.

Extra size... Trim Edge. I like to build doors 1/8 inch larger than required on each side, so when I am done, I can trim the edges on the saw, assuring smooth glue-free end grain on the tops and bottoms, and perfect square on the doors. If I have tear out as I am cutting the profile on the edges of the rail and stile, I can cut 1/16 to 1/8 off the torn-out edge, and cut the profile again (taking the wood I would have later used to square the door). Set cell P5 to the amount you want available to trim, or if you don't want this "feature" set the trim edge to 0.

Many door makers like to cut the edge profile in all the pieces in advance. When figuring the total length needed, the width of the cross-cut saw kerf should be included. That width is in cell P6

If you are using space balls or other pads to keep a raised panel centered, and keep it from rattling, you need to leave room for the compressed space ball. The recommended space for the common 1/4 inch space ball after compression is 5/32, for a little less than 50% compression. If you need 5/32 on each side, overall the raised panel should be 5/16 smaller. Set the size you want raised panels reduced in cell P7. This is only applied to "raised panel" calculations, and only raised panels are included in the overall wood requirement.

Normally glass will be slightly smaller than the opening - most glass shops glue in the glass with silicone rubber, or provide a spacer around the glass. I normally assume that the glass will be 3/16 smaller than the opening in each direction, but you can enter any amount in cell P8.

If you are going to have a curved top, an extremely narrow door doesn't make sense, nor does a door wider than the available templates. For error checking, put the minimum overall door width in P9 and the Maximum door width in P10

If a door is very small, there may not be enough room to have an attractive raised panel. If an overall door dimension is less than the dimension you specify in P11, the spreadsheet will give a warning error if you specify a raised panel, and suggest you consider a flat panel.

Don't change the formulas in column Q of the setup area... those are calculated once to make other formulas simpler. After the setup is complete, turn "protection" and "freeze panes" back on, and save the "master" copy of the spreadsheet, now that it incorporates your preferences.

Using the spreadsheet

Start by putting the project name in cell F12 and saving the spreadsheet with a file name related to the project. This will leave the master copy of the spreadsheet available unchanged for other projects

Starting in row 15, enter an identifier for the door, and the quantity required of that particular size door. This can be a short name or ID number you can put on the parts, and on the door, during construction.

Normally the stiles go the full height of the doors, and the rails are horizontal between the stiles. Therefore enter the door height as the final dimension of the door in the direction of the stiles, and the door width as the final dimension of the door in the direction of the rails. Be sure to add any size required for overlay, not just the size of the opening.

From the drop box in column E, choose the calculations for the center panel...

• blank if you don't want a panel calculated,
• Raised to calculate the dimension of the raised panel or hardwood flat panel, and include the wood requirement for the panel in the total,
• Glass to determine the size of the glass required,
• Flat if you want to calculate the dimensions of a plywood or other panel that does not require space for wood movement. The wood required is not included in the overall total wood requirement.
• Roman or Cathedral to calculate a wider rail at the top, and a center panel that can be trimmed to fit the curved top. There is no difference in the width of the wood required between Roman and Cathedral - the distinction is to allow you to choose the right template.

As data is entered, the total length of the rails and stiles (plus saw kerf) are calculated in inches,and the total is shown in feet. The wider rails for curved tops are not included. The overall wood required for each type of door is also calculated in square feet (board feet assuming all parts are less than 1 inch thick). In practice I have found that there is about 25% waste when making doors from normal hardwood, not considering loss for knots and sapwood, so a gross wood requirement is calculated. You may enter any waste percentage you find useful, and the total wood required will be calculated.

If you print the completed sheet and take it to the shop, you will find the number of doors repeated among the dimensions, to assist you "checking off" the components as they are cut.