Expert Verified Updated: March 2026

Hardness (Total to Calcium) Converter

Estimate calcium hardness from your total hardness test result.

Quick Conclusion
Calcium Hardness typically makes up 70% of Total Hardness in city water. If your Total Hardness is 300 ppm, your Calcium Hardness is likely around 210 ppm.

Technical Comparison

SourceAvg TotalCalcium Fraction
City Water100-300~75%
Well Water400-800~60%
Softened< 50~90%

Actionable Steps

Pro-Tip

If your total hardness is very high but your calcium is balanced, you don't need to worry about scaling. It's the Calcium (Ca2+) that forms the hard white crust on your tiles.

Frequently Asked Questions

Why 25%?

Magnesium typically makes up 20-30% of total hardness in tap water.

Related Tools

General

Baking Soda to Raise Alkalinity by 10 PPM Calculator

Quick calculator to find exactly how much baking soda you need to raise your...
General

Bleach Dosage per 1000 Gallons Calculator

Calculate exactly how much bleach is needed per 1000 gallons to reach your...
General

Borax Pool pH Calculator - Raise pH Safely

Calculate how much 20 Mule Team Borax you need to raise your pool's pH....
General

Borax to Raise pH from 7.0 to 7.4 Calculator

Calculate exactly how much Borax is needed to raise your pool's pH from 7.0...

Get the Complete DIY Pool Maintenance Guide

Free PDF checklist including seasonal schedules, chemical balancing secrets, and maintenance tips.