Pool Pump Flow Rate: How Many GPM Do You Need?

What GPM means in a pool pump listing

GPM stands for gallons per minute. It is the unit a pool pump listing uses to state how much water the pump moves in one minute. A listing may also show GPH, gallons per hour. Both are units of flow, and both describe the pump's stated output, not the flow your pool needs.

A pump title might state a single flow figure in GPH or GPM, or it may show a range that begins with 'up to.' Some listings state no flow figure at all and describe the pump by horsepower and pool type instead. When a figure is absent, the seller has not stated it, and the flow comes from the maker's published performance data. The same listing may appear under several sellers with identical stated figures.

This site reads flow figures as stated in the listing and converts no units. A GPM figure and a GPH figure are different ways of expressing flow; the site reports each as the seller lists it. For the related terms, see flow versus pressure. The inground pump guide and the above ground pump guide show how flow figures appear across listings.

Turnover: what the word means here

Turnover is the term for the period in which a pump circulates a volume of water equal to the pool's water content. It is a common idea in pool equipment discussions and appears in many listings and manuals.

This site does not calculate a turnover rate for your pool and does not match a GPM figure to a pool size. Turnover depends on the pool's gallons, the plumbing layout, filter resistance and the pump's flow at the installed conditions. Those variables are specific to each pool and are best worked out with the maker's sizing page and an installer. The turnover rate article explains the term in more detail.

Where the maker's sizing page fits

Every pump maker publishes sizing guidance or a calculator for choosing a pump by flow and head. Hayward, for example, offers a Total Dynamic Head Calculator on its site, and Pentair publishes flow rate in gallons per minute as a product attribute in its pool pump pages.

Head is the other half of the sizing question. A pump's flow drops as the head, the resistance of the plumbing, rises. A listing may state flow at one head condition and a different flow at another. That is why this site reads the figure as the seller's stated output rather than as a recommendation for your pool. The head in feet article explains the term.

The flow figure in a listing tells you what the pump can state as its output. The flow your pool needs is a separate question. Ask the maker's sizing page first, then confirm with the installer who sees your plumbing, your filter and the distance from the pad to the pool.

What a listing actually states

The distinction matters when you compare two pumps. One listing may state flow in GPM, another in GPH. Since the site converts no units, compare the figures exactly as written and let the maker's performance curve tell you the flow at the operating point.

• A single flow figure states the pump's output at the seller's stated condition.
• A range that begins with 'up to' states the top of the pump's output range.
• A listing that names horsepower but no flow figure leaves flow unstated by the seller.
• A two-figure listing may state flow at two speeds or at two head conditions.

Flow rate and speed types

Speed type changes how a pump delivers flow. A single speed pump runs at one flow rate whenever it is on. A dual speed pump offers two flow settings. A variable speed pump can be set to many flow rates, and a programmable schedule lets it run at different flows for different tasks.

The ENERGY STAR program, which certifies pool pumps, describes pool operation as having different flow needs. Its pool pump page notes that filtration requires only half the flow rate of running a pool cleaner, and it explains that a pump which can adjust speed can match the flow to the task. This site repeats the program's description and makes no claim about energy outcomes.

Compare the variable speed pump guide and the dual speed pump guide when you shop by speed type.

Questions to ask before you buy

Answering those questions before you buy keeps the flow figure in context. The maker's sizing page and the installer, not a general rule, decide what your pool needs. The pool size article and the 2 HP pump guide are the next stops when you shop.

• What flow figure does the listing state, and at what speed or head condition?
• Does the maker publish a sizing page or calculator for this model?
• Does the installer recommend a flow target for your plumbing and filter?
• What is the pump's flow range, not just the top figure?

What to pick for your situation

Questions

What does GPM mean in a pool pump listing?

GPM stands for gallons per minute, the unit a listing uses to state how much water a pump can move in one minute. Some listings use GPH, gallons per hour. Both are flow units; the site reports them as stated and converts no units.

How many GPM does your pool need?

This site does not calculate a GPM target for your pool. The flow your pool needs depends on the plumbing, filter, distance and layout. Use the maker's sizing page and confirm with an installer who sees your system.

What is turnover in pool terms?

Turnover is the period in which a pump circulates a volume equal to the pool's water content. It depends on pool gallons and installed conditions. This site does not calculate turnover or match a flow figure to a pool size.

Is a higher GPM figure always better?

No. The figure is the seller's stated output at a given condition. The right flow for your pool comes from the maker's sizing guidance for your specific plumbing, not from the largest number in a title.

What is the difference between GPM and GPH?

GPM counts gallons per minute and GPH counts gallons per hour. A listing may state either. This site converts no units, so compare the figures exactly as written.