Engineering Guide
Therms, kWh, MMBTU, and BTU: The Complete Energy Billing Units Reference
Published June 27, 2026 · by Industrial Unit Converter Editorial Team
The four energy units in US billing
Every US facility manager deals with at least three energy bills: the electric bill in kWh, the natural gas bill in therms (or CCF), and possibly a steam or chilled water bill in MMBTU or klb. Reconciling these into a single energy budget, and then comparing energy costs across different fuel types, requires fluency in all four units and the conversion factors between them.
This guide covers the conversions an energy manager, building engineer, or sustainability analyst needs: therms to kWh, MMBTU to kWh, BTU to therms, and the reverse directions, plus the fuel cost comparisons that determine whether electrification saves or costs money.
The energy unit hierarchy
| Unit | BTU Equivalent | kWh Equivalent | Where You See It |
|---|---|---|---|
| 1 BTU | 1 | 0.000293 | Equipment thermal ratings, small-scale heat |
| 1 kBtu | 1,000 | 0.293 | Building energy modeling outputs |
| 1 therm | 100,000 | 29.31 | US residential/commercial gas bills |
| 1 CCF | ~102,500 | ~30.05 | Gas meter readings (volume-based) |
| 1 MMBTU | 1,000,000 | 293.1 | Large gas contracts, pipeline tariffs, NYMEX |
| 1 kWh | 3,412 | 1 | Universal electricity billing |
| 1 MWh | 3,412,000 | 1,000 | Large electric accounts |
| 1 GJ | 947,800 | 278 | European gas billing, building energy certs |
The critical conversion: 1 therm = 29.31 kWh
The conversion that matters most for any US building owner comparing gas vs electric heating:
1 therm = 100,000 BTU ÷ 3,412.14 BTU/kWh = 29.3071 kWh
At typical US utility rates:
- Natural gas: $1.50/therm → $1.50 ÷ 29.3 = $0.051/kWh-equivalent
- Electricity: $0.15/kWh → 0.15 × 29.3 = $4.40/therm-equivalent
Gas is 2.9× cheaper per unit of raw energy. But equipment efficiency changes the story.
The efficiency-adjusted comparison: gas vs electric heat
The raw conversion (29.3 kWh/therm) assumes 100% conversion efficiency. Real equipment changes the economics:
Gas furnace at 95% AFUE:
- Delivered heat: 0.95 therms per therm purchased
- Cost per delivered therm: $1.50 ÷ 0.95 = $1.58
- Cost per delivered 100,000 BTU: $1.58
Electric heat pump at COP 3.0 (mild climate):
- Delivered heat: 3 kWh per 1 kWh purchased
- Cost per delivered kWh: $0.15 ÷ 3.0 = $0.05/kWh
- Cost per delivered 100,000 BTU (29.3 kWh): 29.3 × $0.05 = $1.47
Electric heat pump at COP 1.5 (cold climate, −5°F):
- Delivered heat: 1.5 kWh per 1 kWh purchased
- Cost per delivered kWh: $0.15 ÷ 1.5 = $0.10/kWh
- Cost per delivered 100,000 BTU: 29.3 × $0.10 = $2.93
The takeaway: At $1.50/therm gas and $0.15/kWh electricity, a high-efficiency gas furnace and a moderate-climate heat pump are essentially at parity on operating cost. The heat pump wins in mild climates with low electricity rates (Pacific Northwest at $0.08/kWh); gas wins in cold climates and high-electricity-rate regions (Northeast at $0.22/kWh + $2.00/therm gas).
Commercial and industrial scale: MMBTU and MCF
At the commercial/industrial scale, MMBTU replaces therms:
1 MMBTU = 1,000,000 BTU = 10 therms = 293.07 kWh
A large hospital consuming 10,000 MMBTU/month of natural gas (100,000 therms/month) is consuming the thermal energy equivalent of 2,930,700 kWh, about 2.93 GWh. If this hospital also consumes 1,500,000 kWh of electricity per month, its total energy consumption on a common basis is:
- Natural gas: 10,000 MMBTU × 293,070 Wh/MMBTU = 2,931 MWh-equivalent
- Electricity: 1,500 MWh
- Total: 4,431 MWh/month
On a source energy basis (EPA Portfolio Manager source-site ratio of 1.05 for gas and 2.80 for electricity):
- Gas source energy: 2,931 × 1.05 = 3,078 MWh source
- Electric source energy: 1,500 × 2.80 = 4,200 MWh source
- Total source: 7,278 MWh/month
The electricity is only 34% of site energy but 58% of source energy, because of the 2.80× multiplier that accounts for power plant losses. Building electrification can therefore increase site energy consumption while decreasing source energy if the grid is clean.
The CCF confusion (and why 1 CCF ≠ 1 therm exactly)
Your gas meter reads in CCF (hundred cubic feet), a volume measurement. Your gas bill converts CCF to therms by multiplying by the heat content factor, typically 1.020-1.030 (meaning 1 CCF contains 102,000-103,000 BTU).
1 CCF = approximately 1.025 therms
The heat content factor varies monthly based on the gas quality from different supply basins and is printed on your bill. For most cost comparisons, the 2.5% difference between CCF and therms is negligible. For budget forecasting a $500,000 annual gas bill, that 2.5% is $12,500.
NYMEX natural gas: $/MMBTU to $/kWh
The NYMEX Henry Hub natural gas futures contract trades in $/MMBTU. To convert to a fuel cost per kWh:
$/kWh = $/MMBTU × Heat Rate (BTU/kWh) / 1,000,000
For a power plant with a 6,800 BTU/kWh heat rate (52% HHV efficiency):
| Henry Hub Price | Fuel Cost per kWh |
|---|---|
| $3.00/MMBTU | $0.0204/kWh |
| $4.00 | $0.0272 |
| $5.00 | $0.0340 |
| $6.00 | $0.0408 |
| $8.00 | $0.0544 |
At $5.00/MMBTU, the fuel cost of $0.034/kWh is well below the typical US wholesale electricity price of $0.04-0.06/kWh, leaving a spark spread of $0.006-0.026/kWh for the power plant operator.
Carbon accounting: therms and kWh to CO₂
For greenhouse gas reporting (GHG Protocol, EPA 40 CFR Part 98):
Natural gas combustion: 11.7 lb CO₂/therm = 0.00531 metric tonnes CO₂/therm = 53.1 kg CO₂/MMBTU (EPA default emission factor for natural gas burned for heating).
US average grid electricity: 0.82 lb CO₂/kWh (eGRID2022 US national average output rate). Regional values range from 0.20 lb/kWh (upstate NY, hydro-dominated) to 1.50 lb/kWh (parts of the Midwest, coal-heavy).
A building consuming 10,000 therms of gas and 200,000 kWh of electricity annually:
- Gas CO₂: 10,000 × 11.7 = 117,000 lb = 53.1 metric tonnes CO₂
- Electric CO₂ (national average): 200,000 × 0.82 = 164,000 lb = 74.4 metric tonnes CO₂
- Total: 127.5 metric tonnes CO₂/yr
Frequently asked questions
Q: Why does my gas bill show both CCF and therms?
Your gas meter measures volume (CCF). The gas utility converts volume to energy (therms) using the heat content factor because they're selling you energy, not volume. Natural gas from different wells has different heating values (typically 1,000-1,100 BTU/SCF), so volume alone doesn't tell you how much energy you received. The therm (100,000 BTU) is the standardized energy unit.
Q: Should I convert everything to kWh or MMBTU for my energy dashboard?
Either works, but pick one and be consistent. kWh is more intuitive for electrical consumption, MMBTU is the standard for natural gas contracts and EPA reporting. The EPA Portfolio Manager uses kBtu (thousands of BTU): 1 kWh = 3.412 kBtu, 1 therm = 100 kBtu, 1 MMBTU = 1,000 kBtu. If your dashboard is primarily electrical, use MWh and convert gas from therms to MWh (÷3.41). If your dashboard is primarily thermal (steam, hot water, chilled water), use MMBTU.
Related Tools & Calculators
For energy conversion applications in industrial and utility contexts:
- Boiler Efficiency Calculator — See how fuel energy converts to useful heat
- Steam & Boilers Hub — Complete steam engineering reference
- Boiler Efficiency Guide — Direct vs indirect, loss-by-loss
- Steam Boiler Selection Guide — When to choose steam over hot water