Primewright Pump Calculator

Primewright is a pump and piping calculator for pump and irrigation technicians, plumbers sizing mains, fire-protection designers checking a branch, millwrights on hydraulic machinery and students. It works like a hardware calculator: a water-tower blue chassis, real keys and a clear LCD, with each answer labelled so you know what you are reading.

PIPE FLOW
• Flow in gpm (L/s in metric) and pipe size give the velocity: 100 gpm in 2 in Sch 40 steel pipe runs at 9.56 ft/s
• Type a nominal pipe size and get the inside diameter for the material (2 in steel Sch 40: 2.067 in), or type an inside diameter yourself
• Seven materials: steel Sch 40 and 80, copper K, L and M, PVC Sch 40 and 80
• Pipe volume in gallons (litres), the time to fill it at your flow and the weight of the water (300 ft of 2 in pipe: 52.3 gal, 31 seconds at 100 gpm)

FRICTION LOSS
• Hazen-Williams loss per 100 ft (or 100 m) for the flow and pipe, with the C factor of the material or your own (100 gpm in 2 in Sch 40 steel at its C of 120: 21.97 ft per 100 ft)
• Total loss over the pipe length: 300 ft is 65.9 ft of head, or 28.19 psi by the NFPA 13 psi form that sprinkler plan review uses
• Darcy-Weisbach with the Swamee-Jain friction factor, for water at the temperature you set: friction factor, Reynolds number and whether the flow is laminar, in transition or turbulent

PRESSURE AND HEAD
• psi to feet of head and back, with specific gravity for other liquids (50 psi of water: 115.4 ft; at SG 0.85: 135.7 ft)
• Metric: kPa and bar to metres of head and back

PUMPS
• Total dynamic head: static head plus friction head plus the discharge pressure you need (50 ft static and 65.9 ft of friction: TDH 115.9 ft); add fittings to the pipe length as equivalent length
• Brake horsepower and kilowatts from flow, head and pump efficiency, with the water power (4.5 hp at 65 %)
• Affinity laws for a speed change or an impeller trim: a point on the pump curve moved to the new speed (100 gpm at 120 ft, 1750 to 1450 rpm: 82.86 gpm at 82.38 ft). With static head in the system, read the new operating point off the pump curve

FLUID POWER
• Hydraulic cylinder force from bore, rod and pressure: extend and retract force and both areas (4 in bore, 2 in rod at 2000 psi: 25133 lbf out, 18850 lbf back)
• Extend and retract speed from the oil flow (10 gpm: 3.06 in/s out, 4.08 in/s back)
• Metric: a 100 mm bore at 200 bar pushes 157.1 kN

PIPE DATA
• Reference tables: Hazen-Williams C by material, inside diameters of steel pipe, copper tube and PVC pipe, absolute roughness, water density and viscosity by temperature, psi to feet of head

WORKS THE WAY YOU DO
• Imperial (gpm, psi, feet, inches, hp, lbf) or metric (L/s with L/min and m³/h, kPa with bar, metres, mm, kW, N)
• A results strip shows every solved value at once
• 10 memories, a tape of your calculations, reference tables and a key guide
• Export a job strip: the tape with inputs, stamped and ready to attach to a lift plan, sign-off or take-off, as text or PDF

FREE TO TRY, THEN UNLOCK ONCE
Free to try: every feature for 7 days. Then unlock Pro once — no subscription, no ads, works offline.

PRIVATE BY DESIGN
Works offline, no account, no data collected.

How it's calculated: the formulas and tables behind every result, at https://wrightcalc.app/primewright/

Questions or feedback: [email protected]

FOR SIZING CHECKS AND PLANNING ONLY. Primewright does not replace a hydraulic calculation for a permit or the pump maker's curve: verify every result. Hydraulic systems store energy: follow the machine's lockout procedure. The developer accepts no liability for loss, damage or injury arising from use.