Spa Calc
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Comparison

Spa Calc vs FROG Water Care

FROG Water Care is the free app for owners who use FROG sanitizing systems. It reads FROG and FROG @ease strips, gives step-by-step recommendations and dosage guidance, and keeps your testing history, with sign-in. Spa Calc isn't tied to any brand: it takes readings from any kit and works out doses for whatever chlorine, bromine or shock you use.

Prices, features and ratings checked on 28 October 2026.
App Store rating as shown on 28 October 2026: 4.5 stars from 4.9K ratings on the US App Store.

The short answer

If you're committed to FROG, its free app is made for your system and is well rated. If you use other chemicals, switch between brands, or want a soak check, teaspoon doses and a drain countdown without signing in, Spa Calc is free for one tub.

At a glance

From each app's own App Store page and website, checked on 28 October 2026. "Not listed" means we found no mention of it there, not that the feature is missing.
FeatureSpa CalcFROG Water Care
Price Free for one tub Free
Made for Any hot tub and any sanitizer Owners using FROG sanitizing systems
Test strip support Enter values from any strip or drop kit Yes FROG and FROG @ease strips
Dosage guidance Yes Exact amounts for your products Yes Based on test results
Any brand at any strength Yes Not listed
"Ready to soak?" check Yes Not listed
Bromine Yes Not listed
Dichlor then bleach tracker Yes Not listed
Doses in teaspoons Yes Down to an eighth Not listed
Drain and refill countdown Yes Not listed
Inflatable presets Yes Not listed
Testing history Yes With charts Yes
Reminders Yes Not listed
Videos, manuals and dealer finder Written help per reading Yes
Talk to the brand's experts Email support Yes Share history with FROG Customer Service
Account to sign up for None Email sign-in (version notes)
Pools and swim spas Tubs and swim spas; pools in Pool Calc Yes Pool, hot tub or swim spa

Pricing

Our app

Spa Calc

  • Free$0Every feature for one tub, inflatables included.
  • Plus$1.99 a month, $14.99 a year or $39.99 onceUp to 10 tubs plus the host and pro tools. 1-week free trial on the yearly plan.
  • Pro$9.99 a month or $79.99 a yearUnlimited tubs plus the host and pro tools. 1-month free trial on the yearly plan.

Prices on the App Store at launch. Pricing is per person, not per tub.

Brand hot tub app

FROG Water Care

  • FROG Water CareFreeFROG and FROG @ease test strip readings, step-by-step recommendations and dosage guidance for pool, hot tub or swim spa, testing history, videos and manuals, Preferred Dealer.

Free on the App Store, no in-app purchases listed.

Prices as listed on 28 October 2026. Source

Both are free for one tub. FROG's app supports the FROG system you buy. Spa Calc is paid only for more than one tub.

Any sanitizer

FROG's guidance is built around FROG systems. Spa Calc handles chlorine with dichlor then bleach (or bleach only), bromine with a bromide bank, MPS shock, salt water, and ozone, UV and mineral systems, with any product at the strength on its label.

Clear amounts in small units

Spa Calc writes every dose as an amount and a unit for one named product: teaspoons down to an eighth, tablespoons, grams or your own scoop, with a note to check the label.

No sign-in

Spa Calc has no account. Your tub, tests and doses stay on your phone and back up to your own iCloud.

What FROG Water Care Users Complain About

Paraphrased from public reviews. Each one links to where it was posted and gives the month it was written.

  • Advice that changed after an update. A reviewer said the updated app gives balancing advice that conflicts with what they know and called it "completely different and useless" (App Store review, June 2026). The developer replied that the feedback was shared with its technology team.

    Spa Calc approach: one engine for every number, and the "Inputs used" disclosure shows what each dose was based on.

  • Harder to use than it should be. A 2022 reviewer found it informative but wanted a hot tub default and said the color swatch didn't match FROG strips (App Store review, March 2022).

    Spa Calc approach: Spa Calc is hot tubs only, so every screen is about a tub. You read the strip against its own chart and enter the values.

  • A login to check hot tub water. A 2021 reviewer questioned needing an account and raised concerns about data collection and weak password rules (App Store review, December 2021).

    Spa Calc approach: no account and no sign-in.

When FROG Water Care is the better choice

  • You use a FROG system and want guidance written for it.
  • You want the app to read FROG strips.
  • You want videos, manuals, a dealer finder and FROG's customer service in one place.
  • You care for a pool as well, in the same app.

Questions people ask

Do I need the FROG app for my FROG @ease hot tub?

No, but it's made for it. The FROG Water Care listing describes strip readings, recommendations and dosage guidance for owners using FROG systems. Spa Calc doesn't have FROG-specific settings; it works out doses for generic chemicals at the strength on their labels.

Does the FROG app need an account?

Reviews and version notes say yes: version 8.0 added email sign-in with a 6-digit code, and 8.0.5 cut sign-up to first and last name. Spa Calc needs no account.

Is there a hot tub app that works with any chemicals?

Spa Calc works with chlorine (dichlor, bleach), bromine, MPS and salt, at any strength from any brand. One tub is free with every feature. It is on the App Store at launch.

More comparisons

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References

  1. FROG Water Care on the US App Store (rating, description, version notes, reviews: Jun 2026, Mar 2022, Dec 2021), checked 2026-10-28

FROG, FROG @ease and King Technology are trademarks of their respective owners. Spa Calc is not affiliated with them. Information checked on 28 October 2026; prices and features change. Corrections: [email protected]