Grain/gallon to Kilogram/cubic meter Converter
Enter the value that you want to convert grain/gallon (gr/gal) to kilogram/cubic meter (kg/m³) or kilogram/cubic meter to grain/gallon.Also written as GR/GAL to KG/M³ conversion.
1 grain/gallon = 0.0171180 kilogram/cubic meter
Formula: kilogram/cubic meter = grain/gallon value × 0.0171180
GR/GAL to KG/M³ — grain/gallon to kilogram/cubic meter
10 grain/gallon = 0.17118 kilogram/cubic meter
Popular Density Converters:
How Grain/gallon Relates to Kilogram/cubic meter
What is Grain/gallon?
Grain/gallon (gr/gal) is a unit of density measurement. 1 grain/gallon is equal to 0.0171180 kilogram/cubic meter.
The Kilogram/cubic meter in Engineering
Kilogram/cubic meter (kg/m³) is a unit of density measurement. 1 kilogram/cubic meter is equal to 58.4180395 grain/gallon.
Density Conversions in Materials Science
Density units vary by industry: chemists use g/mL or g/cm³, engineers use kg/m³, and American petroleum standards use lb/ft³ or lb/gal. Quality control in manufacturing, buoyancy calculations in naval architecture, concrete mix design, and oil/gas well logging all require converting between density units. Different countries and standards bodies specify materials in different density units.
grain/gallon to kilogram/cubic meter metric conversion table
| 0.01 gr/gal | = | 0.00017 kg/m³ |
| 0.1 gr/gal | = | 0.00171 kg/m³ |
| 1 gr/gal | = | 0.01712 kg/m³ |
| 2 gr/gal | = | 0.03424 kg/m³ |
| 3 gr/gal | = | 0.05135 kg/m³ |
| 4 gr/gal | = | 0.06847 kg/m³ |
| 5 gr/gal | = | 0.08559 kg/m³ |
| 6 gr/gal | = | 0.10271 kg/m³ |
| 7 gr/gal | = | 0.11983 kg/m³ |
| 8 gr/gal | = | 0.13694 kg/m³ |
| 9 gr/gal | = | 0.15406 kg/m³ |
| 10 gr/gal | = | 0.17118 kg/m³ |
| 11 gr/gal | = | 0.18830 kg/m³ |
| 12 gr/gal | = | 0.20542 kg/m³ |
| 13 gr/gal | = | 0.22253 kg/m³ |
| 14 gr/gal | = | 0.23965 kg/m³ |
| 15 gr/gal | = | 0.25677 kg/m³ |
| 16 gr/gal | = | 0.27389 kg/m³ |
| 17 gr/gal | = | 0.29101 kg/m³ |
| 18 gr/gal | = | 0.30812 kg/m³ |
| 19 gr/gal | = | 0.32524 kg/m³ |
| 20 gr/gal | = | 0.34236 kg/m³ |
| 30 gr/gal | = | 0.51354 kg/m³ |
| 40 gr/gal | = | 0.68472 kg/m³ |
| 50 gr/gal | = | 0.85590 kg/m³ |
| 60 gr/gal | = | 1.02708 kg/m³ |
| 70 gr/gal | = | 1.19826 kg/m³ |
| 80 gr/gal | = | 1.36944 kg/m³ |
| 90 gr/gal | = | 1.54062 kg/m³ |
| 100 gr/gal | = | 1.71180 kg/m³ |
| 200 gr/gal | = | 3.42360 kg/m³ |
| 300 gr/gal | = | 5.13540 kg/m³ |
| 400 gr/gal | = | 6.84720 kg/m³ |
| 500 gr/gal | = | 8.55900 kg/m³ |
| 600 gr/gal | = | 10.27080 kg/m³ |
| 700 gr/gal | = | 11.98260 kg/m³ |
| 800 gr/gal | = | 13.69440 kg/m³ |
| 900 gr/gal | = | 15.40620 kg/m³ |
| 1000 gr/gal | = | 17.11800 kg/m³ |
How to Convert GR/GAL to KG/M³ (Grain/gallon to Kilogram/cubic meter)?
We can convert grain/gallon to kilogram/cubic meter by using an example.
Example:
Convert 20 Grain/gallon to Kilogram/cubic meter?
We know 1 Grain/gallon = 0.0171180 kilogram/cubic meter; 1 Kilogram/cubic meter = 58.4180395 grain/gallon.
20 grain/gallon = ___kg/m³
20 × 0.0171180 = 0.34236 kg/m³ (we know 1 grain/gallon = 0.0171180 kilogram/cubic meter)
Answer:
20 grain/gallon = 0.34236 kilogram/cubic meter
Converting Grains per Gallon to kg/m³: Water Hardness and Treatment
Grains per gallon (gpg) is a uniquely American unit used almost exclusively for water hardness measurement and water treatment system sizing. One grain = 1/7,000 of a pound, and combined with a US gallon gives: 1 grain/gallon = 0.017118 kg/m³ (or equivalently, 17.118 mg/L). This unit persists in the water softener industry, municipal water reports, and residential water quality testing.
- Start with the concentration in grains per US gallon.
- Multiply by 0.017118 to convert to kg/m³.
- Or multiply by 17.118 to get mg/L (ppm) directly.
- Verify: 1 gpg = 17.1 mg/L = 17.1 ppm (standard water chemistry reference).
Water Hardness Levels: Grains/Gallon to kg/m³
Water hardness classifications used by water treatment professionals:
| Grain/gallon | Kilogram/cubic meter |
|---|---|
| 0–1.0 gpg | 0–0.017 kg/m³ |
| 1.0–3.5 gpg | 0.017–0.060 kg/m³ |
| 3.5–7.0 gpg | 0.060–0.120 kg/m³ |
| 7.0–10.5 gpg | 0.120–0.180 kg/m³ |
| 10.5–15.0 gpg | 0.180–0.257 kg/m³ |
| 15.0–20.0 gpg | 0.257–0.342 kg/m³ |
| 25.0 gpg | 0.428 kg/m³ |
| 50.0 gpg | 0.856 kg/m³ |
Worked Examples: Grains/Gallon to kg/m³
Question 1: A home water test shows hardness of 12.5 gpg. Express in kg/m³ for comparison with WHO guidelines.
Solution:
Density in kg/m³ = gpg × 0.017118
= 12.5 × 0.017118
= 0.214 kg/m³
Answer: 12.5 gpg = 0.214 kg/m³ (= 214 mg/L) — classified as "very hard" water requiring softening for most household applications.
Question 2: A municipal water supply reports 8.2 gpg hardness. Convert to kg/m³.
Solution:
Density in kg/m³ = gpg × 0.017118
= 8.2 × 0.017118
= 0.140 kg/m³
Answer: 8.2 gpg = 0.140 kg/m³ (= 140 mg/L) — moderately hard water, borderline for needing a softener.
Question 3: A water softener is rated for 30 gpg inlet hardness. What is the maximum inlet concentration in kg/m³?
Solution:
Max concentration = 30 × 0.017118
= 0.514 kg/m³
Answer: 30 gpg = 0.514 kg/m³ (= 514 mg/L) maximum treatable hardness.
Practice: Grains/Gallon to kg/m³
Try solving these on your own to test your understanding:
- Convert 5 gpg (slightly hard) to kg/m³. (Answer: 0.0856 kg/m³)
- Express 18 gpg (very hard well water) in kg/m³. (Answer: 0.308 kg/m³)
- Soft water at 0.5 gpg to kg/m³. (Answer: 0.00856 kg/m³)
- Industrial boiler feedwater limit of 2 gpg in kg/m³. (Answer: 0.0342 kg/m³)
- Extreme hardness of 40 gpg in kg/m³. (Answer: 0.685 kg/m³)
Water Softener Sizing Using Grains
Water softener capacity is rated in "grains of hardness removed per regeneration." A typical residential unit holds 32,000 grains of capacity. For water at 15 gpg, it can treat 32,000 ÷ 15 = 2,133 gallons between regeneration cycles. This grain-based system makes softener sizing intuitive in the US market, but international equipment uses mg/L (= kg/m³ × 1,000), requiring conversion.
Historical Origin of the Grain Unit
The grain is one of the oldest mass units, originally defined as the weight of a single cereal grain (wheat or barley). It equals 1/7,000 of a pound (64.799 mg). While largely obsolete in other fields (except ammunition and pharmacy), grains per gallon persists in water treatment because the entire US softener industry infrastructure — testing kits, equipment ratings, installation manuals — is built around this unit.
Key Takeaways
- 1 grain/gallon (US) = 0.017118 kg/m³ = 17.118 mg/L.
- Primarily used for water hardness measurement in the US.
- Multiply gpg by 17.1 for mg/L (ppm) — the international standard.
- Water softener capacity is rated in total grains removed.
- Hard water starts at about 7 gpg (120 mg/L).
Grain/gallon to Kilogram/cubic meter Conversion Formula
kilogram/cubic meter = grain/gallon × 0.0171180
1 grain/gallon = 0.0171180 kilogram/cubic meter
1 kilogram/cubic meter = 58.4180395 grain/gallon
Reverse: grain/gallon = kilogram/cubic meter × 58.4180395
Frequently Asked Questions
How many kilogram/cubic meter are in 1 grain/gallon?
There are 0.0171180 kilogram/cubic meter in 1 grain/gallon. To convert grain/gallon to kilogram/cubic meter, multiply the value by 0.0171180.
How do I convert grain/gallon to kilogram/cubic meter?
Multiply your grain/gallon value by 0.0171180 to get the equivalent in kilogram/cubic meter. For example, 5 grain/gallon = 5 × 0.0171180 = 0.08559 kilogram/cubic meter.
How do I convert kilogram/cubic meter to grain/gallon?
Multiply your kilogram/cubic meter value by 58.4180395 to get the equivalent in grain/gallon. Alternatively, divide by 0.0171180.
What is 10 grain/gallon in kilogram/cubic meter?
10 grain/gallon is equal to 0.17118 kilogram/cubic meter.
What is 100 grain/gallon in kilogram/cubic meter?
100 grain/gallon is equal to 1.71180 kilogram/cubic meter.