Formulas & assumptions

Unit conventions

• International inch = 0.0254 m; foot = 0.3048 m; yard = 0.9144 m. Area and volume use the square and cube of these factors.
• Acre = 43,560 ft²; hectare = 10,000 m². Liter = 0.001 m³.
• US liquid gallon = 3.785411784 L; Imperial gallon = 4.54609 L. GPM always means US liquid gallons per minute.
• CFM = ft³/min; m³/hr and L/hr use 3,600 seconds per hour.
• Pound (avoirdupois) = 0.45359237 kg. Standard gravity = 9.80665 m/s².
• 1 psi = 6,894.757293168 Pa; bar = 100,000 Pa; kgf/cm² = 98,066.5 Pa; conventional mmHg = 133.322387415 Pa.
• Water head assumes density 1,000 kg/m³: P = ρgh. One meter of water = 9,806.65 Pa. No friction, temperature or fluid-density correction is inferred.
• Mechanical HP = 550 ft·lbf/s = 745.699871582 W. Not metric horsepower (PS), electrical HP or boiler HP.
• International Table BTU = 1,055.05585262 J. 1 TR = 12,000 BTU IT/hr ≈ 3.516852842 kW cooling. Cooling capacity is not electrical power consumption.
• K = °C + 273.15; °C = (°F − 32) × 5/9. Temperatures below absolute zero are rejected.

Source: NIST SP 811 unit factors.

Geometry & flow

• Rectangular area = length × width. Round area = π × diameter² / 4.
• Tank capacity = internal length × width × height. Pipe volume = π × internal diameter² × length / 4. Results are geometric capacity; usable capacity may be smaller.
• Average air velocity = volumetric flow / free cross-sectional area; ft/min = m/s × 60 / 0.3048.
• Slope (%) = 100 × rise / horizontal run; angle = atan(rise/run) × 180/π. Negative rise means a fall. Ratio is rise : run.

Electrical

• Single phase: P(kW) = V × I × PF / 1,000.
• Balanced three phase: P(kW) = √3 × line-to-line voltage × line current × PF / 1,000.
• Reverse current and voltage calculations algebraically rearrange the same equation. Enter actual voltage and power factor; none is assumed.
• kW = kVA × PF. Supported power factor: greater than zero and up to one.
• Energy (kWh) = power (kW) × hours, assuming constant power over the entered duration. It does not include tariffs, demand charges or changing duty cycles.

These tools do not select cable, breaker, generator or equipment sizes.

Nominal pipe sizes

NPS and DN are nominal designations. Neither the DN number nor an inch label multiplied by 25.4 establishes the physical outside or inside diameter. No copper, PVC or PPR diameter standard is inferred.

The NPS/DN designation pairs are cross-checked against the Wheatland ASTM A53 steel pipe reference. Physical OD and wall thickness are deliberately excluded; use the specified material and dimensional standard for selection.

Precision & privacy

Calculations retain JavaScript numerical precision internally. Displayed values generally use up to four decimals; very small or large values use scientific notation. Copy number preserves up to 12 significant digits.

Favorites and recent lists save tool IDs on this device. Entered values stay in the calculator and are not saved to analytics. Usage logging uses the existing ProConnect app analytics system.