About the Even Spacing Calculator
This even spacing calculator divides a length into equal gaps around a set of items. Tell it the total space, how many items you are fitting and how wide each one is, and it returns the gap between them, the centre-to-centre spacing and a position list you can mark straight onto the wall or board — left edge, centre and right edge of every item, with inch measurements rounded to the nearest 1/16 for your tape measure.
Use it for hanging a row of picture frames, spacing shelves up a cabinet side, laying out fence pickets or deck balusters between posts, drilling shelf-pin or dowel holes, or placing cabinet handles and lights. Set the item width to 0 to space points such as holes, nails or screws.
Choose whether the gaps at both ends should match the gaps between items (the usual look for frames and shelves), or whether the first and last items sit flush against the ends (typical for pickets between posts or holes at fixed end positions). Any unit works as long as you use the same one for every entry.
With the default inputs, the gap between items is 9. Change any value above to recalculate instantly.
How to use the even spacing calculator
- 1Measure the total length you have to work with.
- 2Enter the number of items and the width of one item (0 for holes or points).
- 3Choose whether the ends get the same gap or the items sit flush to the ends.
- 4Read the gap and the centre-to-centre spacing.
- 5Use the mark-out table to mark each left edge or centre from your starting point.
Formula and method
Subtract the combined width of all items from the total length to get the free space, then share it out between the gaps. When the ends get the same gap as the spaces between items there are n + 1 gaps; when the first and last items sit flush against the ends there are only n − 1 gaps between them.
The centre-to-centre spacing is one gap plus one item width, which is often the easiest number to step off with a tape. Each item’s left edge is the end gap e (equal to g, or 0 for flush ends) plus k − 1 full spacings; its centre is half an item width further on. Positions are also shown rounded to the nearest 1/16, which assumes you are working in inches.
- L
- Total length available
- n
- Number of items
- w
- Width of each item
- g
- Equal gap
- e
- Gap at each end
Worked examples
Three 20-inch frames on an 8-foot wall
The frames take 3 × 20 = 60 in of the 96 in wall, leaving 36 in. With equal gaps at both ends there are 4 gaps of 9 in. The frame centres fall at 19, 48 and 77 in, 29 in apart.
Ten 3½-inch pickets flush between posts 60 inches apart
Ten pickets take 35 in, leaving 25 in to split into 9 gaps of 2.778 in (about 2-3/4 in). Each picket starts 6.278 in after the previous one, and the first and last touch the posts.
Five shelf-pin holes along a 30-inch side
With zero item width the whole 30 in is divided into 6 equal gaps of 5 in, so the holes go at 5, 10, 15, 20 and 25 in.
Frequently asked questions
How do I calculate equal spacing between objects?+
Subtract the total width of the objects from the space available, then divide by the number of gaps. With equal gaps at both ends there is one more gap than objects; with objects flush to both ends there is one fewer gap than objects.
How far apart should picture frames be on a wall?+
Designers usually leave 2–4 inches between frames in a tight gallery grouping and more for single large pieces. For a row across a wall, using equal gaps at the ends and between frames gives a balanced look; this calculator works out that gap exactly.
How do I space fence pickets evenly?+
Measure between the posts, choose the number of pickets and enter the picket width with flush ends. If the resulting gap is too wide or too narrow, change the picket count. For deck guards, keep the gap under 4 inches to meet the IRC baluster rule.
What is centre-to-centre spacing?+
It is the distance from the middle of one item to the middle of the next, equal to one gap plus one item width. Hooks, holes and studs are usually laid out on centres because you can step the same distance repeatedly along a tape.
Can I use metric units?+
Yes. The math works in any unit — millimetres, centimetres, inches or feet — as long as every entry uses the same unit. The 1/16 fraction readout only makes sense when you are working in inches.