Water Hardness Conversion Calculator
Convert water hardness without mixing units
Water hardness is usually reported as calcium carbonate equivalent. Different test kits and water reports use different units, so this calculator converts one reading into ppm, grains per gallon, and German degrees dH. That makes it easier to compare a home test strip, a municipal report, a softener manual, or a brewing water target.
Enter the hardness value and choose the unit it came from. The calculator converts that input to ppm as CaCO3, then derives the other units from the same ppm baseline.
Formula
1 grain per gallon = 17.1 ppm as CaCO3.
1 German degree dH = 17.848 ppm as CaCO3.
So a 180 ppm reading is about 180 / 17.1 = 10.5 gpg and 180 / 17.848 = 10.1 degrees dH. The page also labels the result as soft, moderately hard, hard, or very hard using common household planning bands.
How to use the result
For appliances and water softeners, grains per gallon is often the practical unit. For aquarium, brewing, and international references, ppm or degrees dH may be easier to match. Keep the source of the reading in mind because total hardness, carbonate hardness, and calcium-only hardness are not the same measurement.
Limits
The conversion is a unit conversion, not a full water chemistry profile. It does not estimate alkalinity, pH, sodium added by softening, chloride, sulfate, or magnesium-calcium balance. Use it to align units first, then use a full water report when those details matter.
Resin Rhythm Hardness Lab
Translate your conversion into motion. Pulses of hard water surge through the lab - tap the canvas or press Space to send a resin burst and keep the gauge hovering in the ideal range before scale takes over.
Pulse resin in short bursts; oversoftening drags stability down too.
Why this calculator fits: Hardness conversions map directly to how much resin a softener must dose. Turning ppm, gpg, and °dH into an active gauge lets visitors feel how quickly a heavy mineral load overwhelms appliances unless you modulate bursts.
Game concept: Resin Rhythm Hardness Lab casts the player as a technician riding surges from the latest conversion. Quick resin pulses relieve pressure, but oversoftening erodes stability, creating a tense 80–90 second arc that swings from calm calibration to frantic recovery and a satisfying glide toward a new best run.
- Controls: Tap/click or press Space/ArrowUp to inject resin bursts, with overlay buttons and Enter-start for accessibility.
- Feedback: Gauge fills, particle ripples, live ppm↔gpg↔°dH readouts, stability bar, and dynamic tips react to every pulse.
- Procedural flow: Spawn timers and pulse strength shift with hardness intensity, ensuring no two runs share the same surge cadence.
Technical approach: A modular canvas loop with ResizeObserver scaling, delta-timed physics, adaptive pulse scheduling, reduced-motion awareness, pause-on-blur handling, and localStorage best tracking ties directly to calculator outputs for a responsive, mobile-ready experience.