How to Measure a Trampoline for Replacement Parts

Most wrong-part returns come from one of two mistakes: measuring the mat instead of the frame, or guessing the spring length. Neither takes more than five minutes to get right, and getting them right is the whole job.

You need three numbers. Write them down, because you will use them for every part you ever buy for this trampoline.

Number 1: frame size, measured outside edge to outside edge

This is the number the entire replacement parts industry uses. A "14 foot trampoline" means the steel frame measures 14 feet across, not the mat.

For a round trampoline: measure straight across the top of the frame, through the center, from the outer edge of the steel on one side to the outer edge on the other. Do it twice at 90 degrees to each other. If the two measurements differ by more than an inch, your frame is out of round, which is worth knowing before you spend money on a mat.

For a rectangle or oval: measure the long side outer edge to outer edge, then the short side the same way. Rectangles are described length by width, for example 9 by 14.

Common results are 8, 10, 12, 12.5, 13, 14, 14.5, 15, and 16 feet. If you land on something odd like 13 feet 4 inches, measure again from a different spot. If it really is a nonstandard size, note it exactly, because some imported frames genuinely are.

Number 2: the spring count

Count every spring around the frame. Not an estimate, an actual count. It is the number that determines how many V-rings the replacement mat needs, and a mat with the wrong ring count will not distribute load correctly even if the diameter is right.

Counting trick: count the springs in a quarter of the circle, mark that spot with a piece of tape, then multiply by four and verify by counting one more quarter. Spring counts are almost always even numbers, commonly 48, 54, 60, 64, 72, 80, 88, 96, or 108.

If some springs are missing, count the empty V-ring positions on the old mat as well, because the mat you order needs a ring for every position the frame has.

Number 3: spring length

Take one spring completely off the trampoline. This matters, because a spring measured while installed is stretched and will read three to five inches long.

Lay the free spring on a flat surface and measure from the outside tip of one hook to the outside tip of the other hook, with the spring relaxed. Common lengths are 3.5, 5.5, 7, 8.5, and 9 inches.

Pick a spring from a low traffic part of the frame for this. A spring from the busiest arc may already be permanently stretched, which would send you toward a longer replacement than you want.

Two more measurements worth taking

• Safety pad width. Measure from the inner edge of the frame rail across the springs to where the mat starts. Add a couple of inches so the pad covers the rail as well. Standard pad widths are 9, 10, 12, 13, and 15 inches.
• Pole count and pole diameter, if you are replacing an enclosure net. Count the poles and measure the outside diameter of one with calipers or a tape wrapped around it. Nets are sold by frame size, pole count, and attachment style.

How the numbers relate

People often expect the mat to be the same size as the frame. It is not, and it should not be. Installed springs are stretched under tension, so the fabric of the mat is roughly two spring lengths plus about eight inches smaller than the frame. A 14 foot frame with 7 inch springs typically takes a mat whose fabric measures around 12 feet 2 inches across.

That is useful as a sanity check, but do not order by the fabric measurement. Order by frame size, ring count, and spring length. Every reputable parts supplier lists mats that way.

Put the numbers to work

Our mat and spring size finder takes those three numbers and returns the exact part specification to order, the estimated mat fabric size as a cross-check, and the safety pad width that will actually cover your springs. It runs entirely in your browser.

Before you order, check the frame

A new mat on a bad frame is money set on fire. Look for rust that has gone past the surface at the leg-to-rail joints, bends in the rails, and elongated holes at the bolt points. Our safety inspection checklist covers the whole assembly in about ten minutes and will tell you whether the frame is worth investing in.