Free Calculator · Published October 2026
CFS to Acre-Feet Converter: Multiply by 1.98
Put a cubic-foot-per-second reading and an acre-foot 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 Acre-Feet Converter Uses 1.98
This page follows one figure on the USGS facts about water page: 1 cubic foot per second = 1.98 acre-feet per day. Gallons per minute stay on the CFS to GPM converter. Multiply cubic feet per second by 1.98. The reverse divides acre-feet per day by 1.98.
Cubic feet per second, or acre-feet 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 Acre-Feet Converter Using?
The printed cubic foot per second is 1.98 acre-feet per day. The result is a unit change. It does not say how large a reservoir 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 stored volume.
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 acre-feet converter uses 1.98 so the acre-foot day rate round-trips. It does not build acre-feet by multiplying 449 and then guessing at a day.
One acre-foot per day divided by 1.98 is about 0.50505. Rounded to four decimals, that display reads 0.5051. The engine divided by 1.98. It did not multiply by 449, and it did not multiply by 0.646.
Worked examples
Each row uses 1.98. One cubic foot per second is 1.98 acre-feet per day. Two cubic feet per second are 3.96. The reverse of 1.98 acre-feet per day is 1 cubic foot per second. One acre-foot per day is 0.5051 cubic feet per second at four decimals.
| Case | Acre-feet per day | Cubic feet per second |
|---|---|---|
| 1 cfs | 1.98 | 1 |
| 2 cfs | 3.96 | 2 |
| 1.98 acre-feet per day | 1.98 | 1 |
| 1 acre-foot per day | 1 | 0.5051 |
A day rate is not a stored volume
Million gallons per day, using 0.646, stays on the CFS to MGD converter. One million gallons as 3.069 acre-feet stays on the million gallons to acre-feet converter. That 3.069 has no seconds and no days. This page has no 449, no 0.646, and no stored million-gallon volume.
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 acre-feet per day.
- The factor, 1.98, named as the USGS acre-foot day-rate line.
- Both results, acre-feet per day and cubic feet per second.
- Which meter, tag, or sheet the flow came from.
- A note that 449, 0.646, and 3.069 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 1.98 note will not swap in 3.069 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 acre-feet converter change?
It converts cubic feet per second and acre-feet per day using 1.98, the figure USGS prints for one cubic foot per second in acre-feet per day. It does not print gallons per minute.
Why not multiply by 449 or by 0.646?
The same USGS sentence prints 449 gallons per minute and 0.646 million gallons per day. Those factors belong on the other CFS converters. This page uses 1.98 only.
Is 3.069 acre-feet used here?
No. USGS prints 3.069 acre-feet for one million gallons. That is a stored volume. This page is a day rate, and it uses 1.98.
Does the result size a well?
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 1.98?
One acre-foot per day divided by 1.98 is about 0.50505. Rounded to four decimals, the display reads 0.5051. The engine divided by 1.98. It did not multiply by 449.
Save 1.98 Next to the Flow
The cubic feet per second, the acre-feet 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.