The practical toolbox
Equal hole spacing calculator
Space hole centres evenly along a straight length. Choose a count or maximum spacing, set end margins, and follow a visual marking plan.
Save this version with its URL. Bookmark this page or copy its link to reopen your inputs later. Save a new link after making changes. Anyone with the link can read your inputs. Results are recalculated on reopening; print a copy if you need a fixed record.
Create a saved link with AI
Give your AI assistant your measurements or figures and the instructions below. It can create a ready-to-open link for this hole-spacing plan. Open the link, check the inputs, then bookmark it or copy the URL to reuse it later.
Copy this prompt and add your information:
Read https://www.lejnel.com/hole-spacing-url-guide.txt and generate a clickable saved-plan URL for my hole-spacing plan. Convert my units to the guide’s required units. Ask for missing inputs instead of guessing, and explain any assumptions. Return the link and a summary of the inputs used.
Read the URL format and examples · AI instructions for all tools
The URL contains your inputs. Anyone with the link can read them. Future calculator updates may change results; retain a printed copy when you need a fixed record.
Your marking plan
Every centre, accounted for.
Coloured circles are the hole footprints; crosses mark their centres. Match each numbered colour badge to the marking list below. Colours repeat on longer rows; the hole number identifies the exact position. Teal dotted dimensions above the row show centre-to-centre spacing. Brown dotted dimensions beside the holes show the clear gap between the edges of each pair of holes. A negative clear gap means the holes overlap. The strip’s height is illustrative; the horizontal dimensions and hole diameters share a scale. Swipe sideways on a phone.
Mark from the same starting edge
Measure every centre from the starting edge to avoid accumulating rounding errors. Values are rounded for display; calculation uses full precision.
How equal hole spacing is calculated
Usable centre span = total length − start margin − end margin. For a chosen hole count, centre spacing = usable span ÷ (number of holes − 1). The clear distance between adjacent hole edges is centre spacing − hole diameter.
When you choose a maximum spacing, the calculator rounds the number of gaps up so the actual spacing is no larger than your limit. It adds one to get the number of holes and keeps your entered end margins.
Example: five holes across a 1,000 mm length
With 50 mm from each end to the nearest hole centre, the usable span is 900 mm. Five holes create four gaps, so each centre gap is 225 mm. Mark centres at 50 mm, 275 mm, 500 mm, 725 mm and 950 mm from the same starting edge. With an 8 mm diameter, the clear gap between holes is 217 mm.
Hole spacing questions
Are the end margins measured to the hole edge or centre?
They are measured to the centre. For example, a 50 mm end margin with an 8 mm hole leaves 46 mm from the material edge to the nearest hole edge. Check the required edge allowance for your material and fixing.
Why do five holes have only four gaps?
Each gap connects two adjacent centres. A straight row with N holes has N − 1 centre gaps. The start and end margins are separate.
Can I choose the spacing instead of the number of holes?
Yes. Select Maximum centre-to-centre spacing. The calculator chooses enough holes to keep equal gaps at or below that maximum while preserving your entered end margins. It may therefore use a slightly smaller actual spacing.
Can I use inches or print a marking plan?
Yes. Switch to Imperial for decimal-inch inputs and measurements. Print layout includes the diagram and numbered centre positions. Measure from a fixed starting edge; the printed picture is not a full-size template.
Can this calculate a grid or circular bolt pattern?
This tool calculates one straight row. It does not calculate two-dimensional grids, circular bolt patterns or structural fixing requirements.
Disclaimer & use of this calculator
This tool lays out one straight row of equal circular holes. It does not establish suitable fastening distances, structural capacity, edge strength, material suitability or a safe drilling location. Check the actual workpiece, product instructions, required edge distances and concealed services. Printed diagrams are not full-size drilling templates.
Results depend on your inputs and may contain errors. Independently verify all measurements before work. To the extent permitted by applicable law, lejnel.com disclaims warranties and liability for loss, damage, injury, wasted materials and costs arising from use of this calculator. Nothing excludes liability or statutory rights that cannot lawfully be excluded or limited. See the Terms of Use.
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