CCF stands for “hundred cubic feet” (the C comes from the Roman numeral for 100). It’s the standard billing unit on most water and natural gas utility bills in the United States. Calculating CCF is straightforward once you know the conversion factors: 1 CCF equals 100 cubic feet, which equals 748 gallons of water or roughly 1.038 therms of natural gas.
What CCF Means on Your Bill
Your water or gas meter measures volume as it flows through a pipe, and the utility reads that meter periodically to determine how much you used. Rather than billing in raw cubic feet, most utilities bill in units of 100 cubic feet, abbreviated as CCF (sometimes also written as HCF, for “hundred cubic feet”). If your bill shows 5 CCF, that means you used 500 cubic feet of water or gas during the billing period.
How to Calculate CCF for Water
The key number to remember is that one cubic foot of water holds 7.48 gallons. Since one CCF is 100 cubic feet, one CCF equals 748 gallons.
To convert between CCF and gallons, use these formulas:
- CCF to gallons: CCF × 748 = gallons
- Gallons to CCF: gallons ÷ 748 = CCF
For example, if your bill shows 8 CCF, you used 5,984 gallons that billing cycle. If you know your pool holds 15,000 gallons and you want to figure out the cost to fill it, divide 15,000 by 748 to get about 20 CCF, then multiply by your utility’s rate per CCF.
A typical household in a city like Portland uses about 5 CCF per month, or roughly 15 CCF per quarter (about 7 CCF per person over three months). If your usage is significantly higher than that, it could signal a leak or an irrigation issue worth investigating.
How to Read Your Water Meter
If you want to calculate your own CCF between billing cycles, you can read your water meter directly. Most residential meters work like a car’s odometer: a row of numbers that rolls forward as water flows through. Some meters also have a sweep hand (like a clock hand) that represents the smallest unit of measurement, filling in the digits that don’t appear on the odometer.
To calculate usage, take two readings at different times. Write down the number shown on the register, subtract the earlier reading from the later one, and you have your total consumption in whatever unit the meter displays. Many meters read in cubic feet, so dividing by 100 gives you CCF. Some meters read directly in gallons, in which case you’d divide by 748 to convert to CCF. Check your meter face for the unit of measure, since different manufacturers use different scales.
For example, if your meter read 45,200 cubic feet on June 1 and 45,700 cubic feet on July 1, you used 500 cubic feet, or 5 CCF, that month.
How to Calculate CCF for Natural Gas
Natural gas bills also use CCF, but the math works a bit differently because gas is measured by energy content, not just volume. The energy in natural gas varies slightly depending on its composition and where it comes from, but the U.S. annual average is about 1,038 BTU per cubic foot.
That means 1 CCF of natural gas contains approximately 103,800 BTU, which equals 1.038 therms (a therm is 100,000 BTU). Many gas utilities bill in therms rather than CCF, so knowing how to convert between them is useful:
- CCF to therms: CCF × 1.038 = therms
- Therms to CCF: therms ÷ 1.038 = CCF
If you’re comparing gas prices between utilities or regions, you can also convert dollar amounts. Divide the price per CCF by 1.038 to get the price per therm, which gives you an apples-to-apples comparison regardless of how each utility formats its rates. Keep in mind that the heat content of natural gas can vary by location and over time, so your local utility may use a slightly different conversion factor on your bill.
Calculating Cost From CCF
Once you know your CCF usage, calculating your cost is simple multiplication. Find the rate per CCF on your utility bill (it’s usually listed in the rate summary or charges section), then multiply:
Total usage in CCF × rate per CCF = usage charge
Many utilities use tiered pricing, where the first block of CCF costs less and higher usage costs more. In that case, you’ll need to apply the lower rate to the first tier and the higher rate to any usage above that threshold. For instance, if your utility charges $3.50 per CCF for the first 10 CCF and $5.00 per CCF above that, and you used 14 CCF, your charge would be (10 × $3.50) + (4 × $5.00) = $55.00, before any fixed service fees.
Some bills also include separate charges for sewer service, which is often calculated as a percentage of your water CCF on the assumption that most water entering your home eventually goes down the drain. If you use a lot of water outdoors for irrigation, some utilities offer a separate irrigation meter so that outdoor water isn’t included in your sewer calculation.