Make room for your art.

A rabbet is a step cut along the edge of a piece of wood. For a one-piece floating frame, that step sits behind the canvas and forms a ledge underneath it. The recessed-panel alternative has a rear rabbet that seats a separate plywood support panel. In the standard frame, the step is cut from the back and leaves a front lip over the artwork. Each solid frame rail is one continuous piece; the recessed-panel construction also needs its separate plywood panel.

The letters beside your inputs match the cross-section drawing. Start with the frame face width and how much wood sits under or over the artwork. For a floating canvas, you also choose the empty gap and how far back the canvas sits. Open “Fine-tune the fit & depth” for the less common adjustments.

For a one-piece floating frame, recess depth = canvas thickness + the distance it sits back from the frame front. Total wood depth adds the solid wood left behind that recess. With a recessed back panel, the rear seat depth equals the actual plywood thickness; total frame depth = canvas thickness + setback + plywood thickness. For a standard frame, recess depth = the complete artwork package + room for fasteners. Those are editable starting measurements; check your hardware and material.

Choose “Set recess depth myself” to override the calculation. A shallow floating-frame recess makes the canvas project forward, which the drawing and measurements will show. A standard frame must still fit its full package and leave solid wood at the front.

Each rail has a 45° miter at both ends. Measure its outside edge between the long tips. Measure its innermost full-blank edge between the short tips. On a floating frame, this is the back ledge edge under the canvas; its length is shorter than the visible opening. On a standard frame, it is the front-opening edge.

The cut list always measures the full-width blank. Keep the profile orientation consistent when routing and cutting. Finished dimensions exclude blade and waste allowances.

Choose “Use boards I have” and add your boards one at a time using actual usable dimensions after any milling and edge cleanup. Canvas or artwork dimensions stay as entered. The calculator adapts the frame face and depth while preserving your gap, overlap, ledge and minimum retained wood.

On edge, board width becomes frame depth and may be ripped smaller. Flat, board thickness becomes frame depth and width may be ripped to match the common profile; no planing or resawing is assumed. A deeper floating frame puts the canvas farther back. Add each usable length and quantity to check all four rails, including cutting allowances. Boards can have different widths and lengths; only boards that yield the same finished rail profile are combined. Incompatible entries are listed separately. Unknown lengths cannot confirm enough material. A cross-section fit alone does not mean you have enough wood.

The cut list gives the finished rectangular blank before you cut the rabbet. For a one-piece floating frame, its profile width is frame face width + gap + ledge under the canvas. For the recessed-panel version, the rail blank is the frame face width, and the plywood panel is a separate material. Its depth runs front to back. The board-buying plan chooses the smaller requested dimension as stock thickness, rounds up once to a nominal hardwood grade, and retains that orientation. Extra usable thickness widens the face or thickens retained wood; for a back-panel frame it may increase canvas setback. All drawings, cut lengths and material estimates use the resulting profile; the grain still runs along each rail.

Rough quarter grades describe nominal thickness: 6/4 is nominally 1 1/2″ before surfacing, not a promise of its final size. The rough option reserves adjustable material for milling. The surfaced option uses typical final usable thicknesses: 4/4 → 3/4″, 5/4 → 1″, 6/4 → 1 1/4″, 8/4 → 1 3/4″. This nominal-minus-1/4″ assumption is not a universal S2S thickness or a guaranteed yield. A requested 1 1/8″ therefore rounds up to 6/4 under the default assumptions. Some sellers can yield 1 1/8″ from 5/4; confirm actual usable thickness and use the actual-board workflow for such stock. Measure stock before buying. The calculator does not rate strength or select fastening hardware; choose joinery and hardware for the frame’s size and weight.

The optional blade allowance assumes eight separate 45° cuts. Blade width is measured perpendicular to the blade, so estimated length consumed at 45° is blade width × √2 per cut. Waste percentage is then added. This is an estimate, not a cutting sequence or board layout.

Spline sizes depend on the corner layout, slot, and stock. Confirm the profile, mounting clearance, and joinery with a test assembly before final cutting.