Workshop tool

Bench Dog-Hole Layout Planner

Fix the pitch. Balance the ends. Mark every hole from one datum.

Bench length

Whole millimetres, 600 to 4000.

Bench width

Whole millimetres, 300 to 1500.

Dog-hole diameter

Measure the hardware you intend to use. Up to two decimal places, 5 to 50 mm.

Fixed centre spacing

The exact pitch to keep between rows and columns. Whole millimetres, 50 to 300.

Minimum end margin

Minimum hole-centre clearance at both short ends. The planner centres the grid and may return a larger actual margin.

Front-row offset

Exact distance from the front edge to the first row of hole centres. Whole millimetres, 25 to 300.

Minimum rear margin

Minimum distance from the last row centre to the rear edge. Whole millimetres, 25 to 300.

Add a vice or no-drill zone?

The planner removes any hole whose edge plus your clearance would overlap this rectangle.

No exclusion

Add rectangular zone

Zone X start

From the left end of the bench, whole millimetres.

Zone X end

Must be greater than X start and stay inside the bench.

Zone Y start

From the front edge of the bench, whole millimetres.

Zone Y end

Must be greater than Y start and stay inside the bench.

Extra zone clearance

Added outside the zone before the hole radius is checked; 0 to 100 mm.

WORKED EXAMPLE

108 holes18 columns × 6 rows before exclusions

Layout summary
Value	Measurement	Note
Bench top	1800 × 700 mm	70 7/8 in × 27 1/2 in
Hole diameter	20 mm	3/4 in
Fixed pitch	96 mm	3 3/4 in
Actual end margins	84 mm each	3 1/4 in
Front row centre	80 mm	3 1/8 in
Rear clearance	140 mm	5 1/2 in
Candidate positions	108	0 omitted

Hole centres from the front-left corner

Row centre	X centres in mm
Y 80 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716
Y 176 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716
Y 272 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716
Y 368 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716
Y 464 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716
Y 560 mm	84, 180, 276, 372, 468, 564, 660, 756, 852, 948, 1044, 1140, 1236, 1332, 1428, 1524, 1620, 1716

Mark every coordinate from the same front-left datum corner; do not chain measurements from one hole to the next.
The pitch stays fixed at 96 mm. Only the end margins are balanced.
No vice or no-drill exclusion was applied to this layout.
Check the underside for vice hardware, rails, fixings and aprons before drilling.

This is the tool's worked example, not your figures: an 1800 × 700 mm bench, 20 mm holes on a fixed 96 mm pitch, 60 mm minimum end margins and the first row 80 mm from the front edge. Load it into the form with the example button, or enter your own and press the calculate button to replace it.

This planner needs JavaScript to generate a coordinate list in your browser— nothing is sent anywhere. On paper, subtract twice the minimum end margin from the bench length, divide by the pitch and round down to get the number of intervals. Add one for the columns, then centre that fixed-pitch run. For rows, start at the front offset and add the pitch until the next row would breach the rear margin. The worked example above is 18 columns × 6 rows: 108 holes, 84 mm end margins and 140 mm at the rear.

How this works

Inputs

Enter the bench-top length and width, the dog-hole diameter you have measured, a fixed centre-to-centre pitch, minimum end margins, an exact front-row offset and a minimum rear margin. The optional rectangle uses X from the left end and Y from the front edge, all measured from the same front-left datum corner.

Method

The grid never stretches the requested pitch. It fits the greatest whole number of pitch intervals inside the available length and shares the leftover equally between the two ends. The first Y row remains at your front offset; later rows use the same pitch until the next one would breach the minimum rear margin.

columns = floor((length − 2 × min end margin) ÷ pitch) + 1actual end margin = (length − (columns − 1) × pitch) ÷ 2

rows = floor((width − front offset − min rear margin) ÷ pitch) + 1rear margin = width − (front offset + (rows − 1) × pitch)

With an exclusion, the planner expands its rectangle by half the hole diameter plus the extra clearance. A candidate centre inside that expanded rectangle is omitted, ensuring the edge of the hole does not enter the specified clearance zone.

Rounding

Inputs are retained exactly in millimetres. Column and row intervals round down because a partial pitch is not a hole position. A half-millimetre end margin can occur when an odd leftover is shared equally. Imperial equivalents round independently to the nearest 1/8 in; use the metric coordinate ledger as the construction record.

Limitations

The rectangle models one simple no-drill area; irregular vice hardware may need more manual omissions.
Coordinates describe the top face only. Check aprons, rails, vice screws and fixings underneath before drilling.
The planner does not decide dog diameter, commercial-system compatibility, top thickness or structural adequacy.
This is a planning aid, not an engineering or safety certification.

Worked example

BD-1: an 1800 × 700 mm top, Ø20 mm holes, 96 mm pitch, 60 mm minimum end margins, an 80 mm front-row offset and 60 mm rear minimum. Seventeen X intervals use 1632 mm, leaving 168 mm and therefore 84 mm at each end. Five Y intervals place six rows at 80, 176, 272, 368, 464 and 560 mm, leaving 140 mm at the rear. With no exclusion, the result is 108 holes.

Sources

The centring, coordinate and rectangle-overlap rules are elementary geometry documented above; no external spacing standard is claimed. Hole diameter, pitch, margins and clearance are reader-supplied design choices, not recommendations from this site.