SettingsSettings for this calculationUS
The friction head loss per 100 ft (or 100 m) of pipe run, from a pipe sizing chart or a Hazen-Williams friction loss calculation at the design flow rate.
This rate comes from the system's actual pipe sizing chart or a Hazen-Williams calculation for the chosen pipe size and design flow rate — this calculator does not derive it, it only scales it by the total equivalent length.
The straight pipe length plus the equivalent length of all fittings, valves, and equipment in the circuit's index (longest/most-resistant) run.
Add the actual straight pipe length to the equivalent length contributed by elbows, tees, valves, and other fittings along the index circuit — the single loop with the greatest total resistance, which sets the pump's required head.
Total pump head required
10 head units
Friction loss rate must come from your system's actual pipe sizing chart or Hazen-Williams calculation for the design flow rate — this calculator only scales that rate by total equivalent length; it does not calculate the friction loss rate itself.
They open the calculator with your figures already in it
Hydronic Circulator Pump Head Loss Calculator: 10 head units — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Total head loss = friction loss rate per 100 ft/m of pipe × (total equivalent pipe length ÷ 100), the standard method for sizing a circulator pump's required head once the system's friction loss rate is known (from a pipe sizing chart or Hazen-Williams calculation) and combined with the total equivalent length including fittings
Inputs used
- Friction Loss Rate (Head Units per 100 ft/m of Pipe)
- 4
- Total Equivalent Pipe Length (Straight Pipe + Fittings)
- 250
Confidence note: Friction loss rate must come from your system's actual pipe sizing chart or Hazen-Williams calculation for the design flow rate — this calculator only scales that rate by total equivalent length; it does not calculate the friction loss rate itself.
What this calculation does not cover
- Head on its own selects no circulator. A pump is chosen where the required head and the design flow meet on its curve, so this figure has to be carried forward with the same flow rate the friction loss rate was read at — two systems needing identical head at very different flows take entirely different pumps.
- Plain water is assumed. A 30 to 50 percent propylene glycol charge is thicker and heavier, raising circuit friction at the same flow and cutting the flow any given pump delivers, so a snowmelt slab or a freeze-protected loop sized from a water friction rate ends up short of flow at the far end of the circuit.
- In a closed loop the pump lifts nothing — the down-leg balances the up-leg — so building height belongs nowhere in this figure and adding it oversizes the pump. The reverse applies to an open circuit such as a drainback array or an open tank: there the vertical rise from the water surface to the discharge is real head, and it is not included here.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Total head loss = friction loss rate per 100 ft/m of pipe × (total equivalent pipe length ÷ 100), the standard method for sizing a circulator pump's required head once the system's friction loss rate is known (from a pipe sizing chart or Hazen-Williams calculation) and combined with the total equivalent length including fittings
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