Lumbertool Calculate board feet

Woodworking spacing and marking layout

Mark equal clear gaps between solid items, or lay out hole centres at an explicitly selected pitch.

Try the calculation

Example inputs · U.S. customary units

Three equally spaced items in a 36 in span. Confirm equal-gap or fixed-pitch mode first; they answer different layout questions.

Example: 36 in.

Example: 3 items.

Example: 0.75 in.

Results

Ready to calculate

Enter your values, then choose Calculate. Your results will appear here.

How to use woodworking spacing and marking layout

What this calculation does

This layout tool separates equally spaced solid items from fixed-pitch hole rows because their positions refer to different physical points.

Choose equal-gap or hole-row mode first, then enter only the measurements shown for that mode and use one datum.

Enter the measurements

  1. Layout method: Choose equal clear gaps between items or a fixed-pitch row of hole centers.
  2. Span: In equal-gap mode, enter the full available span.
  3. Number of solid items: Count the solid items to space.
  4. Actual width of each item: Measure the actual width of each item.
  5. First hole centre from datum: In hole mode, measure the first center from the datum.
  6. Last allowed hole centre from datum: Enter the last center allowed from that same datum.
  7. Centre-to-centre pitch: Enter center-to-center hole pitch.

Formula and variables

Equal gap = (span − count × item width) ÷ (count + 1); item starts = gap + i × (width + gap). Hole count = floor((last allowed centre − first centre) ÷ pitch) + 1; centres = first + i × pitch.

Equal gaps divide unoccupied width into count+1 spaces; returned positions are item leading edges. Hole count and centers use floor division by the entered pitch.

Read the result

Three 0.75 in items in 36 in leave 8.4375 in at each boundary; leading edges are 8.4375, 17.625 and 26.8125 in.

Worked example

Inputs: 36 in span with three 0.75 in items

  1. Clear gap = (36−3×0.75)÷(3+1) = 8.4375 in.
  2. Leading edges are 8.4375, 8.4375+(0.75+8.4375), and that value plus 9.1875.

Expected result: 8.4375 in clear gaps and leading edges at 8.4375, 17.625 and 26.8125 in

Frequently asked questions

Are equal-gap positions item centers?

No. They mark each item’s leading edge from the same datum.

Does hole-row mode choose hardware pitch?

No. Enter the pitch and limits selected for your hardware or layout.

Conditions, presets and technical notes

Equal-gap positions are the leading edges of the solid items, not their centres. Fixed-pitch positions are hole centres. Use one datum throughout. Pitch and edge setbacks are user or hardware choices; this tool does not prescribe 32 mm systems, fastener capacity or building-code spacing. At most 500 marks are displayed.