How the research is done

From the documents makers publish, then from public records. A dealer's figure is used only where the maker publishes nothing, and it is labeled as a dealer figure.

Seven rules decide what goes on the site.

1. Maker first. The spec sheet, manual or warranty document beats a dealer page, and a dealer figure is labeled when it is all there is.
2. Every figure keeps its link. The dot after a figure opens the document it was read from, not our summary of it.
3. No source, no number. A blank field means the maker doesn't say. We don't fill it with an estimate.
4. Contradictions are published. When a maker's documents disagree, both answers go up with both sources. 2,379 are on record.
5. A second pass re-read the sources. All 390 hot tubs were checked again against the original documents by a pass that did not trust the first. Its results are on how we verify every figure.
6. Energy filings are matched by maker and model number. A filing we can't tie to one model with confidence is left out, not guessed.
7. Photos are never borrowed. If a model has no second photograph, the space stays empty.

From the sourced figures, by fixed rules, each time the site is built. These are the rules.

Medians

The middle value of the tubs that publish the figure, or the mean of the middle two when the count is even. Each page names its base: how many spec sheets the median was taken from. A seat range such as 5 to 6 counts as its lower figure.

Same-size comparisons

A tub's peers are the tubs whose California filing lists a fill volume within 60 gallons of its own, and we compare only when there are at least 8. “Less standby power than X% of same-size tubs” is the share of those peers that draw more.

Running cost

Standby watts x 730 hours a month x 18.19 cents per kWh, the EIA US residential average for January to July 2026. It is a floor: soaking, refills and cold weather add to it. See hot tub running cost.

Build checks

Each hot tub brand is checked on 8 construction points (self-supporting shell, clamped plumbing, manifold-fed jets, standard parts, compression-fitted jets, adjustable jets, service network and american made?). Each verdict reads Yes, Partly, No or Not published, with its evidence linked. Swim spa brands get 10. See the hot tub buying guide.

Best picks

Ranked on facts only: build checks passed, shell warranty years and standby power against same-size tubs. No rating, review score or price goes in. See how the best hot tubs were picked.

Warranties

A lifetime term counts as 100 years when warranties are sorted, and always shows as “Lifetime”.

From the makers that post them openly on their own websites: Bullfrog, Caldera, Catalina (LPI), Dimension One, Endless Pools, Hot Spring, Master Spas, Wellis. We read each model's page and record the figure, the page and the day we checked it, and label it as the maker's list price (MSRP), its “starting at” price, or, for Bullfrog, the starting range for a whole series. Master Spas figures are reported prices, with the month.

A maker that hides its price behind a form, or posts none, reads “Price on request”: a dealer's quote is the only real figure. We never estimate a price, and never print a reported price as a maker's. A general cost, such as installation or wiring, appears only with its public source named in the sentence. What owners reported paying is on what a hot tub costs, labeled as owner reports with their years.

Whenever a source changes, and every page shows when that last happened. The date at the top of a page is the day its facts were last checked; it moves only when they are read again.

A re-check is due when a maker changes a document or a model year, a new California filing appears, the CPSC posts a recall, or a reader reports an error. The last full reads: hot tub specifications Sep 20 to 21, 2026, swim spas Sep 27, 2026, brand records Sep 23 to 24, 2026. Every page and dataset is listed by date on the update log.

On the page itself, next to the figures it explains. These are the main ones.

• How we verify every figurethe second-pass audit, contradictions and what we still don't know
• How the best hot tubs were pickedthe three bars every pick has to clear
• Best hot tubs for cold climateshow the picks were made
• Best hot tubs for back painhow the picks were made
• Best hot tubs for tall peoplehow the picks were made
• Best hot tubs for seniorshow the picks were made
• How the best swim spas were pickedthe facts each swim spa pick rests on
• Best swim spas for lap swimminghow the picks were made
• Hot tub running costwhat the measured standby figure includes and leaves out
• Most energy-efficient hot tubsevery matched California filing, ranked within its size
• Hot tub sizeswhere the size medians come from
• The 8 build checkswhat each check means and how each brand was graded
• Hot tub reviews and ratingswhich public records exist, and what a BBB grade measures
• Hot tub recallsevery CPSC recall for the brands we track
• What a hot tub costsreported prices and what owners paid