How Deionization (DI) Works
How DI works, when to use it, and how to reach ultra‑low TDS/resistivity with RO to DI.
Read ArticleWater Hardness Converter
Input your hardness value in TDS, grains per gallon, or calcium & magnesium levels to instantly convert hardness levels between ppm, gpg, and °dH and see how hard your water is instantly.
Your Water Hardness Results i
—
—
Hardness (ppm)
—
Grains per Gallon
—
Category
Soft
Moderate
Hard
Very hard
Hardness (ppm as CaCO₃)
—
Grains per gallon (gpg)
—
German degrees (°dH)
—
Categories (US EPA/AWWA convention): Soft ≤ 60 ppm, Moderately hard 61-120 ppm, Hard 121-180 ppm, Very hard > 180 ppm.
Your Recommended Treatment Option:
From Numbers to Answers
We make your water hardness results simple, accurate, and actionable.
Proven Formula
We use trusted formulas to deliver precise hardness conversions—so you can feel confident in your results, no matter the unit.
Instant Results
Instantly see your results in multiple units (ppm, gpg, °dH), making calculations and comparisons quick and easy.
Personal Recommendations
Based on your inputs, we recommend the most effective hard water treatment options—tailored to your water needs, budget, and lifestyle.
Water Hardness Tips for Accurate Results and Smart Treatment Choices
Get the Most Accurate Reading
Use the right units: Enter your hardness value in ppm, gpg, or °dH, whichever you already have from your test.
Stay consistent: Stick with the same unit each time you test for reliable comparisons.
Track Changes Over Time
Seasonal shifts: Water hardness can change throughout the year. Retest every few months to stay up to date.
Different sources: If you switch between city water and well water, test both to avoid surprises.
Match Results to Treatment
Know your category: Soft, moderate, hard, or very hard, your results will guide the best treatment option.
Smart choices: Use your hardness level to decide between a salt-free conditioner, softener, or simple filter.
Already Know Your Water Hardness?
Now that you have your results, shop the best water softener systems or connect with an expert to find the right solution. Don’t worry—we’ll help you every step of the way.
Frequently Asked Questions
Clear answers about water hardness, testing, units, and the best treatment options, written to help you use our calculator and pick the right water softener for your home.
What is water hardness and why does it matter?
Water hardness is the amount of dissolved calcium and magnesium in your water, commonly shown as ppm (mg/L), gpg (grains per gallon), or °dH. Hard water can leave spots, create scale in pipes and appliances, reduce soap performance, and dry out skin and hair. Knowing your hardness helps you decide if you need a water softener, salt-free conditioner, or simple filtration. Use our water hardness calculator to convert units and see your category—soft, moderate, hard, or very hard—so you can choose the right solution with confidence.
How do I measure the hardness of my water at home?
Use an at-home test strip kit, a digital hardness/TDS meter, or request a water quality report from your utility. Enter your result into our water hardness calculator to convert between ppm, gpg, and °dH and to see your hardness category. For the most accurate comparison over time, test from the same tap, follow the kit instructions carefully, and use the same unit whenever you retest.
What’s the difference between ppm, gpg, and °dH?
PPM (mg/L as CaCO₃) shows parts per million of hardness. GPG (grains per gallon) is common in the U.S.—1 gpg = 17.1 ppm. °dH (German degrees) is used in parts of Europe—1 °dH ≈ 17.8 ppm. Our converter instantly translates your number across units so you can read any guide, compare systems, and shop with confidence.
What levels are considered soft, moderate, hard, or very hard?
Soft: 0-60 ppm (0-3.5 gpg) • Moderately hard: 61-120 ppm (3.6-7 gpg) • Hard: 121-180 ppm (7.1-10.5 gpg) • Very hard: 180+ ppm (10.6+ gpg). Soft water usually needs no treatment. Hard and very hard water often benefit from a softener or conditioner. Enter your value in our calculator to see your category instantly.
What are the common signs of hard water at home?
Look for white, chalky spots on glasses and fixtures, soap that doesn’t lather well, stiff laundry, scale on showerheads and heating elements, and skin or hair that feels dry. If you notice these symptoms, test your water and use our calculator to confirm hardness and explore the best treatment options for your home.
How does hard water affect plumbing, appliances, and skin?
Mineral scale builds up inside pipes, water heaters, and appliances, lowering efficiency and shortening lifespan. It also reduces detergent performance, leaving residue on dishes and clothes. On skin and hair, hard water can feel drying. Matching your test result to the right treatment—softener for very hard water or a salt-free conditioner for moderate hardness—protects plumbing, improves cleaning, and helps your home run more efficiently.
What is the best treatment for hard water in my home?
It depends on your hardness level and goals. For very hard water, a traditional salt-based softener removes calcium and magnesium for maximum scale prevention. For a low-maintenance, eco-friendly option, a salt-free conditioner crystallizes minerals so they don’t stick to surfaces—great for moderate hardness. Some homes add whole-house filtration for taste and odor. Use our calculator result and category to match the right system.
What’s the difference between a water softener and a salt-free conditioner?
A water softener uses ion exchange to remove calcium and magnesium, producing truly soft water and preventing scale entirely. A salt-free conditioner doesn’t remove minerals; it changes their structure so they don’t adhere to surfaces. Conditioners are lower-maintenance and ideal for moderate hardness, while softeners are best for very hard water or when you want maximum scale protection throughout the home.
How often should I test my water hardness?
Test at least once a year, and any time you notice changes in taste, scale, or soap performance. Hardness can shift seasonally, after plumbing work, or if your water source changes (e.g., city vs. well). Retesting every few months helps verify your treatment system is working and keeps your calculator results current.
Can well water and city water have different hardness levels?
Yes. Well water often has higher hardness because it absorbs minerals from rock and soil. City water varies by source and local treatment and can range from soft to very hard. If you use a well—or switch sources—test regularly and enter your value in our calculator to confirm hardness and select the right treatment for consistent results.
Explore Our Educational Articles on Water Filtration
Read expert-written educational articles on water quality, filtration technology, and treatment solutions
Ion Exchange for PFAS Removal: A Comprehensive Guide to Effective Water Filtration
Discover ion exchange for PFAS removal in water. Learn about resins, comparisons and uses.
Read Article
Understanding Ion Exchange: The Water Filtration Process Behind Cleaner, Safer Water
Discover how ion exchange works and why it’s essential for removing contaminants like calcium, le...
Read Article