Free Calculator · Published October 2026
CFS to MGD Converter: Multiply by 0.646
Put a cubic-foot-per-second reading and a million-gallon day rate on the same line before anyone treats them as two flows.
Built by SubcontractorHub — the software plumbing contractors use to quote, finance, and run every job.
Book a DemoHow the CFS to MGD Converter Uses 0.646
This page follows one figure on the USGS facts about water page: 1 cubic foot per second = 0.646 million gallons per day. Gallons per minute stay on the CFS to GPM converter. Multiply cubic feet per second by 0.646. The reverse divides million gallons per day by 0.646.
Cubic feet per second, or million gallons per day. Not a minute rate.
All calculations are estimates based on historical information and should be verified by the user.
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 Is the CFS to MGD Converter Using?
The printed cubic foot per second is 0.646 million gallons per day. The result is a unit change. It does not say how large a well is, how much chemical to feed, or whether a plant passed a permit. Write both labels on the ticket so the next visit does not treat a day rate as a minute rate.
One factor, both directions
The water-facts page prints 1 cubic foot per second as 449 gallons per minute, as 0.646 million gallons per day, and as 1.98 acre-feet per day. This CFS to MGD converter uses 0.646 so the day rate round-trips. It does not build million gallons by multiplying 449 and then guessing at a day.
One million gallons per day divided by 0.646 is about 1.54799. Rounded to four decimals, that display reads 1.548. The engine divided by 0.646. It did not multiply by 449, and it did not multiply by 1.98.
Documentation that places the minute-rate conversion beside this day-rate conversion publishes two incompatible interpretations of the identical stream measurement, and the office should identify the publication, the multiplication factor, and the time unit before the customer treats a deliberately omitted gallon-per-minute calculation as part of the day-rate result.
Worked examples
Each row uses 0.646. One cubic foot per second is 0.646 million gallons per day. Two cubic feet per second are 1.292. The reverse of 0.646 million gallons per day is 1 cubic foot per second. One million gallons per day is 1.548 cubic feet per second at four decimals.
| Case | Million gallons per day | Cubic feet per second |
|---|---|---|
| 1 cfs | 0.646 | 1 |
| 2 cfs | 1.292 | 2 |
| 0.646 million gallons per day | 0.646 | 1 |
| 1 million gallons per day | 1 | 1.548 |
A day rate is not a minute rate
Million gallons per day turned into gallons per minute, using 1,440 minutes, stays on the MGD to GPM converter. A steady gallon-per-minute rate times 1,440 stays on the GPM to GPD converter. A million-gallon volume with no time stays on the million gallons to cubic feet converter. This page has no 449, no 1.98, and no minutes.
What to write on the job ticket
Write five lines before the number leaves this page. A later visit should not have to guess which factor was used.
- The entered value, and whether it was cubic feet per second or million gallons per day.
- The factor, 0.646, named as the USGS day-rate line.
- Both results, million gallons per day and cubic feet per second.
- Which meter, tag, or sheet the flow came from.
- A note that 449, 1.98, and 1,440 were not applied.
What stays off this unit change
A stream gauge and a plant meter can both be called a flow. This page does not ask which instrument produced the number. A pump curve that talks about gallons per minute is a different tool, and this converter does not replace it.
A water treatment dealer who saves the 0.646 note will not swap in 449 and call the result a day rate. This conversion does not size a softener and does not say a sample passed a county rule. A private-well lab sheet is still the well water testing guide.
Frequently Asked Questions
What does this CFS to MGD converter change?
It converts cubic feet per second and million gallons per day using 0.646, the figure USGS prints for one cubic foot per second in million gallons per day. It does not print gallons per minute.
Why not multiply by 449 gallons per minute?
The same USGS sentence prints 449 gallons per minute and 1.98 acre-feet per day. Those factors belong on the CFS to GPM converter. This page uses 0.646 only.
Is 1,440 minutes used?
No. Gallons per minute times 1,440 is the GPM to gallons-per-day converter. This page does not start from a minute rate.
Does the result size a pump?
No. The result is a unit change between two flow labels. It does not read a well tag, a pipe diameter, or a chemical dose.
What is 1 divided by 0.646?
One million gallons per day divided by 0.646 is about 1.54799. Rounded to four decimals, the display reads 1.548. The engine divided by 0.646. It did not multiply by 449.
Save 0.646 Next to the Flow
The cubic feet per second, the million gallons per day, and the USGS day-rate line 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 size a pump.