Interactive decision tools
Calculate with your evidence, not somebody else’s assumptions.
Use disclosed formulas for sizing, flow and ownership cost. Every result keeps unknowns visible and tells you what still needs property-specific or exact-model verification.
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- Working calculators
- Formula shown
- On every result
- No login
- Inputs stay in your browser
- Evidence-limited
- No automatic product endorsement
Available now
Choose the decision you need to make.
Water hardness calculator
Convert mg/L, grains per gallon, °dH and mmol/L, see the USGS scale, and calculate total hardness from a calcium and magnesium lab result.
- Four-unit conversion
- USGS scale output
- Total-hardness formula
Water-softener sizing calculator
Turn hardness and household water use into a disclosed working-capacity target, then check an exact model’s usable capacity and flow.
- Hardness unit conversion
- Bill or household-use inputs
- Working-capacity formula
Whole-house flow-rate calculator
Build a realistic simultaneous-fixture scenario or use a measured flow, then compare it with documented rated service flow.
- Editable fixture rates
- Measured-flow option
- Pressure-loss check
Ten-year treatment cost calculator
Compare installation, financing, consumables, service, utilities and planned replacement work over a common ten-year window.
- Year-by-year schedule
- Financing and remaining balance
- Shareable assumptions
How the tools work
The arithmetic is useful only when the inputs are honest.
These tools calculate from values you provide. They do not invent a hardness result, product capacity, price, service life or local availability when the evidence is missing.
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Use measured or documented inputsPrefer a current test, bill, meter, exact-model specification or written quote.
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Review the disclosed formulaEach result shows how your inputs become the planning output.
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Verify the remaining boundaryConfirm exact performance, pressure, installation and local conditions before buying.
Research standard
Tools support the decision; they do not replace verification.
See how Water System Guide separates measured evidence, derived guidance and unknown states.Publisher boundary: Water System Guide is an independent research publisher, not a manufacturer, dealer, installer, utility or laboratory.