A hot tub cover is a consumable part. It spends its life under sun, weather, and steam, and eventually it stops doing its job. The good news is that replacing one is straightforward — as long as you measure it correctly, because covers are built to order and a wrong number means a cover that doesn't fit.

Signs it's time

The clearest sign is weight. Covers absorb moisture as they age, and a waterlogged cover gets heavy enough to be a two-person job to open — heavy enough, eventually, to tear its own lift brackets out of the foam. If yours is getting hard to lift, it's past due.

Beyond that: panels that sag in the middle, seams splitting, vinyl cracking, or a cover that no longer sits flat and seals around the rim. A cover that doesn't seal is costing you money every day in lost heat.

Why you can't just order a stock size

Covers are custom-built, and "7 by 7" isn't enough information. Your old cover has also likely stretched or shrunk over the years, so it's not a reliable template either. Measure the tub, not the old cover.

That said — measure the old cover before you take it off, just to see how far it has drifted from the tub's actual dimensions. It tells you what you're dealing with.

What you need to record

All you need is a tape measure and a square.

1. Overall dimensions. Measure side to side and front to back, to the outside edge of the tub. On a square or rectangular tub this is a two-person job — have someone hold the end of the tape. Always round up to the next full inch. If you measure 75½, order 76. If you measure 75¼, still order 76. Never round down.

2. Corner radius. This is where most orders go wrong. Lay your tape across the corner where it just touches, and measure in to find the radius. Always round down to a whole inch, and never spec a half inch — if you measure 2½, order a 2-inch radius. If you're unsure between two sizes, go with the smaller one. Taking an inch off is something you'll never notice. Going an inch too big means the cover won't sit right in the corners.

On a six-sided or octagonal tub, also measure point to point around the corners and confirm they all match.

3. Skirt length. We spec 6 inches unless there's a reason not to. A longer skirt still keeps dirt and leaves out, and it gives you room to vent the cover in summer — propping one edge with a pool noodle or a tennis ball lets trapped heat escape so your water doesn't climb past comfortable on hot days. A 4-inch skirt doesn't leave enough material to do that.

4. Fold direction. Note which way your cover folds. It determines how the cover is built and which way it opens.

5. Color.

6. Make, model, and year of your spa.

With those six pieces of information, a cover can be built to fit your tub exactly.

Don't overlook the straps

Cover safety straps are held to the same legal standard as a fence around a pool, and the rules have changed over the years. Straps belong at the four corners — never centered on a side, where a child could force the cover up, and never along the fold. If you're replacing a cover, replace the old hardware with it rather than reusing clips that may no longer meet current requirements.

What about the cover lift?

If yours is more than a few years old, consider replacing it at the same time. A cover lift typically lasts 7 to 15 years, but the plastic brackets tend to fail at 5 to 7 — and a heavy, waterlogged cover accelerates that considerably. Swapping both at once means one job instead of two.

Need help?

If you've got your dimensions, radius, skirt length, fold direction, color, and the make and model of your spa, we can get you a cover. If you'd rather not measure it yourself, we'll come do it — it takes about 35 minutes to measure, remove the old cover, and install the new one. And I know a local mom-and-pop shop in Mason, OH that makes great covers!