Free Calculator · Published October 2026
CFS to GPM Converter With the USGS Printed 449 Factor
Read a stream, a ditch, or a pump test in the unit the next person expects, without swapping in a different day-count.
Built by SubcontractorHub — the software plumbing contractors use to quote, finance, and run every job.
Book a DemoA CFS to GPM Converter Uses 449
This CFS to GPM converter follows the flow line on the USGS water facts page. One cubic foot per second equals 449 gallons per minute. A casing recovery test is a different question, on the well recovery rate calculator. Pump horsepower is the well pump size calculator.
A measured rate. Not a 24-hour total unless you say so on the ticket.
Liters per minute are not one of these choices.
Important: All calculator results are ballpark estimates
All calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements.
What the CFS to GPM Converter Is Using
449, 0.646, and 1.98 from one sentence
USGS prints one cubic foot per second as 449 gallons per minute, as 0.646 million gallons per day, and as 1.98 acre-feet per day. The minute rate multiplies and divides by 449. The other two results multiply the cubic-feet figure by 0.646 and by 1.98.
No fourth factor is added. If you enter gallons per minute, the page divides by 449 first, then applies 0.646 and 1.98 to that cubic-feet result. All three stay on the sentence USGS printed for one cubic foot per second.
Worked examples
The first row is the USGS line itself. The half-cfs row is that line cut in half. The 449 gallon row reverses the minute factor and should land back on 1 cubic foot per second.
| Case | cfs | gpm | Mgal/d |
|---|---|---|---|
| 1 cfs (USGS line) | 1 | 449 | 0.646 |
| 0.5 cfs | 0.5 | 224.5 | 0.323 |
| 449 gpm | 1 | 449 | 0.646 |
Why 1,440 is not the day factor here
A steady gallon per minute, times 1,440 minutes, is 1,440 gallons in a day. That arithmetic is true, and it is not what this page is doing. USGS already printed the day figure for one cubic foot per second as 0.646 million gallons.
Using 449 times 1,440 would show 646,560 gallons. That is a different rounding than the printed 0.646 million. Write 0.646 when you mean the USGS line. Do not relabel it as an exact 1,440 conversion.
A contractor who copies only the minute rate, and then multiplies by a day count from a different handbook, is no longer reading the USGS sentence. The printed million-gallon figure and the printed acre-foot figure travel with the cubic-foot rate. Leave both attached, with 0.646 and 1.98 named, so the next reader can see which published sentence was used.
What to write on the job ticket
The entered value, the direction, the gallons per minute, and the million-gallons figure, with 449 and 0.646 named. A water treatment dealer who is checking whether a well can backwash a filter still needs the backwash rate calculator. This conversion does not size that filter, does not state a removal percentage, and does not certify a yield. The testing list for what else to order is the well water testing guide.
Frequently Asked Questions
What does a CFS to GPM converter change?
It converts cubic feet per second and gallons per minute using 449, the factor USGS prints for one cubic foot per second. The same sentence prints 0.646 million gallons per day and 1.98 acre-feet per day, and those scale with the cubic-feet figure. It does not use 1,440.
Why not 1,440 gallons per day per gallon per minute?
There are 1,440 minutes in a day, and 449 times 1,440 is 646,560 gallons. USGS prints 0.646 million gallons per day for that same one cubic foot per second. This page follows the printed factors so the three results stay the sentence you can point at.
Is this a well yield?
No. It changes the unit of a flow you already measured or were given. Specific capacity and casing recovery are a different calculator. A pump curve is a different page. None of those results are a certified safe yield.
Does the tool convert liters or cubic meters?
No. USGS also prints liter and acre-foot facts on the same water-facts page. This converter stays on the one flow sentence: cubic feet per second, gallons per minute, million gallons per day, and acre-feet per day.
Can I size a softener from this number?
Not from the unit change alone. A softener needs a daily volume and a hardness, on their own pages. A flow in cubic feet per second is only the rate. Write the unit next to it so nobody treats 1 as 1 gallon.
Save the Flow Unit Next to the Test
Cubic feet per second, gallons per minute, and the factor you used belong on the customer record.
Get a Free DemoAll calculations are estimates based on historical information and should be verified by the user. This tool is provided as a free service for planning purposes only and is not a substitute for a professional assessment, a supplier quote, or applicable local code requirements. It does not certify a well yield.