Plumbing Unit Converter: Imperial to Metric Calculator
Convert PSI to kPa, GPM to L/min, inches to mm, and °F to °C instantly. Professional plumbing unit conversion calculator with accurate results for contractors and engineers.
Unit Converter
Temperature Converter
Common Temperature References
32°F = 0°C
68-70°F = 20-21°C
98.6°F = 37°C
212°F = 100°C
Quick Conversion Reference Table
| Imperial Unit | Metric Equivalent | Common Use |
|---|---|---|
| 1 PSI | 6.895 kPa | Water pressure |
| 1 GPM | 3.785 L/min | Flow rate |
| 1 inch | 25.4 mm | Pipe diameter |
| 1 foot | 0.3048 m | Pipe length |
| 1 gallon | 3.785 L | Tank capacity |
| 32°F | 0°C | Freeze protection |
How to Convert Plumbing Units
Pressure Conversion
PSI to kPa: multiply by 6.895
kPa to PSI: divide by 6.895
Example: 50 PSI × 6.895 = 344.75 kPa
Flow Rate Conversion
GPM to L/min: multiply by 3.785
L/min to GPM: divide by 3.785
Example: 10 GPM × 3.785 = 37.85 L/min
Length Conversion
Inches to mm: multiply by 25.4
mm to inches: divide by 25.4
Example: 2 inches × 25.4 = 50.8 mm
Temperature Conversion
°F to °C: (°F - 32) × 5/9
°C to °F: (°C × 9/5) + 32
Example: 68°F = (68-32) × 5/9 = 20°C
Standard Pipe Size Conversions
Imperial to Metric Pipe Sizes
Critical Design Values
Plumbing Unit Conversion FAQ
How do you convert PSI to kPa for water pressure?
Multiply PSI by 6.895 to get kPa. For example: 50 PSI × 6.895 = 344.75 kPa. This conversion is exact and used for all water pressure calculations in plumbing.
What is 1 GPM in liters per minute?
1 GPM equals 3.785 liters per minute. To convert any GPM value, multiply by 3.785. This is the standard conversion for all plumbing flow rate calculations.
How many mm is a 1 inch pipe?
1 inch = 25.4 mm exactly. However, nominal pipe sizes differ: a "1 inch" pipe is actually 25mm nominal in metric sizing. Always check actual inside diameter for flow calculations.
How to convert Fahrenheit to Celsius for plumbing?
Use the formula: °C = (°F - 32) × 5/9. For common plumbing temperatures: Cold water 50°F = 10°C, Hot water 140°F = 60°C, Boiling 212°F = 100°C.
What does water weigh in Imperial vs Metric units?
In US units, water weighs approximately 8.34 pounds per gallon (1 kg per 3.785 liters) or 62.4 pounds per cubic foot (1,000 kg per cubic meter). A 100-foot (30.5-meter) run of 6-inch pipe holds about 177 gallons (670 liters), weighing roughly 1,475 pounds (670 kg). For metric calculations, water weighs 1 kilogram per liter or 1,000 kilograms per cubic meter. This weight is important for structural calculations, especially in multi-story buildings.
Why don't more countries use the imperial system?
Most of the world uses metric because it's simpler - everything is base 10, and units relate logically to each other. The US still uses imperial mostly because of the massive cost of switching over existing infrastructure, manufacturing, and habits. But even in the US, science, medicine, and military use metric. It's really just construction and everyday life that stick with imperial.
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Universal Unit Conversion for Plumbing
Most plumbing calculations involve mixed units. Use these calculators with built-in conversion capabilities: