Hydration · Most Popular
Daily Water Intake Calculator
Get your personal daily water target based on weight, activity, and climate. The "8 glasses a day" rule is too generic — this isn't.
Free Tools Hub · 2026
Water Tools — free calculators & converters.
Five science-backed water and hydration tools in one place. Use them to plan your daily intake, check your tap water quality, estimate softener costs, convert units, or find refill stations near you. No signup, no email, no ads in the way.
5
Free Tools
~30s
Avg Use Time
$0
Cost
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Calculators & Tools
Stop guessing. Start measuring.
Free, instant, accurate. Built around the questions our readers actually ask.
Body Composition · Watson Formula
Body Water Percentage Calculator
Estimate your body water percentage using the Watson formula — the same one used in clinical research. Adults are typically 50–65% water.
Tap Water · EPA Standards
Water Quality Checker
Quick assessment of pH, TDS (Total Dissolved Solids), and turbidity — find out if your tap water needs filtering, or if it's already fine.
Home Cost · Salt & Salt-Free
Softener Cost Estimator
Get realistic install + running costs before any salesman quotes you. Covers salt-based, salt-free, dual-tank, and whole-house systems.
Conversion · 15+ Units
Water Weight Converter
Gallons, liters, ounces, kilos — every unit you'd ever convert. Handles US vs UK gallons properly. Perfect for cooking and aquariums.
AI-Powered · ZIP Code Search
COâ‚‚ & Refill Finder
Find SodaStream COâ‚‚ exchanges and 5-gallon water refill stations near you. Live retailer prices and locations, by ZIP code.
How These Work
Built on actual research, not guesses.
Every tool here uses peer-reviewed formulas, official guidelines, or tested data. Not marketing math.
01. Peer-Reviewed Formulas
Watson formula for body water, IOM hydration guidelines for daily intake — published, tested, used by clinicians.
02. EPA & FDA Standards
Water quality thresholds match EPA Safe Drinking Water Act standards. No invented "ideal" numbers.
03. Real Retailer Data
Cost estimators use current US/UK retail pricing — refreshed monthly so quotes don't go stale.
04. Privacy-First
Nothing is stored on our servers. No accounts, no tracking pixels, no email harvesting. Calculate & close.