What Is BTU in Gas Measurement?
BTU stands for British Thermal Unit — the amount of energy needed to raise the temperature of 1 pound of water by 1°F. Despite its name, the BTU is far more commonly used today in the United States than in the UK. In 2026, UK domestic gas bills use kWh, but BTU remains the dominant unit for gas appliance output ratings (boilers, furnaces, cookers, HVAC systems), US gas billing, and some legacy commercial contracts.
kWh
joules
m³
BTU = 1 therm
The BTU to M3 Formula
Converting BTU to cubic metres requires the calorific value (CV) because BTU is energy and m³ is volume — the same volume of gas holds more energy at higher CV. The conversion first transforms BTU into kWh (a fixed step), then kWh into m³ (which requires CV). The Ofgem volume correction factor of 1.02264 adjusts for gas temperature and pressure at the meter.
How to Convert BTU to M3 — Step by Step
Find Your BTU Value
Common BTU sources: gas boiler output plate, US energy bill, appliance data sheet, HVAC system specification, or gas range/oven rating. Most UK boiler plates show kW output — multiply by 3,412 to convert kW to BTU/hr. US bills show annual usage in therms (÷ 0.00001 to get BTU) or MMBTU (× 1,000,000 to get BTU).
Identify Your Gas CV
For UK pipeline gas, use 39.5 kWh/m³ if your exact CV is unknown. For LNG supply or non-UK sources, check the delivery certificate or contract. The difference between CV 38.5 and CV 42.0 changes the m³ result by about 9% — significant for commercial-scale conversions.
Apply the Formula
Multiply BTU by 0.000293001 to get kWh, then multiply by 3.6 to get MJ, then divide by (CV × 1.02264) to get m³. Or simply multiply by the simplified factor for CV 39.5: BTU × 0.0000261. The calculator above does this instantly.
Verify & Account for Boiler Efficiency
The BTU figure on a boiler plate is usually the output rating. To find actual gas input (what comes out of the pipe), divide by the boiler efficiency. Modern A-rated condensing boilers are 92–94% efficient. Older G-rated boilers may be only 65–75% efficient.
Worked Examples — BTU to M3
÷ (39.5 × 1.02264)
= 2.611 m³
= 0.783 m³/hr
(CV 39.5 avg)
= 1.567 m³/hr
(CV 39.5 avg)
= 26.11 m³
Same as MMBTU→M3
÷ (42.0 × 1.02264)
= 2.454 m³
× 3412.142 ÷ 3.6
= 382,900 BTU
UK Boiler BTU Sizing Reference 2026
UK boilers are rated in kW but US specification sheets and some older documents use BTU/hr. Use this reference to cross-check output ratings and understand gas flow rates. All m³/hr figures assume CV 39.5 kWh/m³ and represent maximum output — average consumption will be lower depending on thermostat control and heating schedule.
| Boiler Output | kW Equiv. | BTU/hr | m³/hr (CV 39.5) | m³/day (8hr/day) | Typical Property |
|---|---|---|---|---|---|
| 5.3 kW | 5.3 kW | 18,000 | 0.470 m³/hr | 3.76 m³ | Studio flat |
| 7.0 kW | 7.0 kW | 24,000 | 0.626 m³/hr | 5.01 m³ | 1-bed flat |
| 8.8 kW | 8.8 kW | 30,000 | 0.783 m³/hr | 6.26 m³ | 2-bed house |
| 10.3 kW | 10.3 kW | 35,000 | 0.914 m³/hr | 7.31 m³ | 3-bed (UK avg) |
| 12.3 kW | 12.3 kW | 42,000 | 1.097 m³/hr | 8.77 m³ | 4-bed house |
| 14.7 kW | 14.7 kW | 50,000 | 1.305 m³/hr | 10.44 m³ | Large 4-bed |
| 17.6 kW | 17.6 kW | 60,000 | 1.567 m³/hr | 12.53 m³ | Large detached |
| 29.3 kW | 29.3 kW | 100,000 | 2.611 m³/hr | 20.89 m³ | Small commercial |
m³/hr = BTU/hr × 0.000293001 × 3.6 ÷ (39.5 × 1.02264). Daily m³ assumes 8 hrs running. Actual gas input higher — divide m³/hr by boiler efficiency (typically 0.92) for real gas consumed.
BTU to M3 Conversion Table 2026
Full reference table at UK national average CV 39.5 kWh/m³ with VCF 1.02264. Key milestones — 1 therm (100,000 BTU) and 1 MMBTU (1,000,000 BTU) — are highlighted. For LNG or non-standard CV, use the calculator above.
| BTU | M3 (CV 39.5) | kWh | Therms | MMBTU | MJ |
|---|---|---|---|---|---|
| 1,000 | 0.02611 m³ | 0.2930 kWh | 0.01 | 0.001 | 1.055 MJ |
| 5,000 | 0.1306 m³ | 1.465 kWh | 0.05 | 0.005 | 5.275 MJ |
| 10,000 | 0.2611 m³ | 2.930 kWh | 0.10 | 0.01 | 10.55 MJ |
| 18,000 | 0.470 m³ | 5.274 kWh | 0.18 | 0.018 | 18.99 MJ |
| 24,000 | 0.626 m³ | 7.032 kWh | 0.24 | 0.024 | 25.32 MJ |
| 30,000 | 0.783 m³ | 8.790 kWh | 0.30 | 0.030 | 31.65 MJ |
| 50,000 | 1.306 m³ | 14.65 kWh | 0.50 | 0.050 | 52.75 MJ |
| 100,000 (1 therm) | 2.611 m³ | 29.30 kWh | 1.00 | 0.100 | 105.5 MJ |
| 200,000 | 5.222 m³ | 58.60 kWh | 2.00 | 0.200 | 211.0 MJ |
| 500,000 | 13.056 m³ | 146.5 kWh | 5.00 | 0.500 | 527.5 MJ |
| 1,000,000 (1 MMBTU) | 26.11 m³ | 293.0 kWh | 10.0 | 1.000 | 1,055 MJ |
| 3,412,142 (1 kWh) | 89.12 m³ | 1,000 kWh | 34.12 | 3.412 | 3,600 MJ |
| 5,000,000 | 130.6 m³ | 1,465 kWh | 50.0 | 5.000 | 5,275 MJ |
| 10,000,000 | 261.1 m³ | 2,930 kWh | 100 | 10.00 | 10,550 MJ |
M3 to BTU Conversion Table 2026
Reverse reference for converting gas cubic metres back to BTU. Useful when you have a meter reading and need to express consumption in BTU for US appliance comparisons, HVAC engineering or commercial contracts. All values at CV 39.5 kWh/m³ with VCF 1.02264.
| M3 Gas | BTU (CV 39.5) | kWh | Therms | MMBTU | Est. Cost (7.42p) |
|---|---|---|---|---|---|
| 0.1 m³ | 3,829 BTU | 1.118 kWh | 0.038 | 0.0038 | £0.08 |
| 0.5 m³ | 19,145 BTU | 5.591 kWh | 0.191 | 0.019 | £0.41 |
| 1 m³ | 38,290 BTU | 11.18 kWh | 0.383 | 0.038 | £0.83 |
| 2 m³ | 76,580 BTU | 22.36 kWh | 0.765 | 0.077 | £1.66 |
| 5 m³ | 191,450 BTU | 55.91 kWh | 1.914 | 0.191 | £4.15 |
| 10 m³ | 382,900 BTU | 111.8 kWh | 3.829 | 0.383 | £8.29 |
| 20 m³ | 765,800 BTU | 223.6 kWh | 7.658 | 0.766 | £16.59 |
| 26.11 m³ (1 MMBTU) | 1,000,000 BTU | 293.0 kWh | 10.00 | 1.000 | £21.74 |
| 50 m³ | 1,914,500 BTU | 559.1 kWh | 19.14 | 1.914 | £41.49 |
| 100 m³ | 3,829,000 BTU | 1,118 kWh | 38.29 | 3.829 | £82.98 |
| 200 m³ | 7,658,000 BTU | 2,236 kWh | 76.58 | 7.658 | £165.9 |
| 1,029 m³ (UK avg/yr) | 39,410,000 BTU | 11,500 kWh | 392.5 | 39.25 | £853.3 |
| 1,000 m³ | 38,290,000 BTU | 11,180 kWh | 382.9 | 38.29 | £829.6 |
BTU = m³ × CV × VCF × 3412.142 ÷ 3.6. Cost at Ofgem Q2 2026 approximate unit rate 7.42p/kWh — always verify against your actual tariff. UK avg/yr row uses Ofgem medium benchmark 11,500 kWh.
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BTU per M3 by UK Region & Gas Source 2026
The number of BTU in each cubic metre of gas varies by region and supply source. The difference between Scotland's lower CV gas and richer South East pipeline gas is approximately 5% — relevant for precise engineering calculations. For LNG, the variation is larger still.
| Gas Source / Region | CV (kWh/m³) | Band | BTU per m³ | m³ per 100,000 BTU | m³ per MMBTU |
|---|---|---|---|---|---|
| UK North East England | 37.5 | Low | 36,360 BTU | 2.75 m³ | 27.50 m³ |
| Scotland | 37.2–40.0 | Low–Avg | 36,070–38,800 | 2.58–2.77 m³ | 25.77–27.70 m³ |
| North West England | 37.8–40.0 | Below Avg | 36,650–38,800 | 2.58–2.73 m³ | 25.77–27.30 m³ |
| Yorkshire & Humber | 38.0–40.2 | Average | 36,850–38,990 | 2.57–2.71 m³ | 25.74–27.10 m³ |
| Wales | 38.0–40.2 | Average | 36,850–38,990 | 2.57–2.71 m³ | 25.74–27.10 m³ |
| West Midlands | 38.5–40.5 | Average | 37,330–39,270 | 2.55–2.68 m³ | 25.45–26.83 m³ |
| 🇬🇧 UK National Average | 39.5 | Avg | 38,290 BTU | 2.611 m³ | 26.11 m³ |
| South West England | 38.8–41.0 | Average | 37,620–39,760 | 2.51–2.66 m³ | 25.13–26.58 m³ |
| East Midlands | 39.0–40.8 | Average | 37,810–39,540 | 2.53–2.64 m³ | 25.26–26.44 m³ |
| London & South East | 39.0–41.5 | Above Avg | 37,810–40,240 | 2.49–2.64 m³ | 24.85–26.44 m³ |
| Norway LNG/pipeline | 40.0–43.5 | High | 38,800–42,190 | 2.37–2.58 m³ | 23.70–25.77 m³ |
| Qatar LNG (Qatargas) | 42.0 | LNG | 40,720 BTU | 2.454 m³ | 24.54 m³ |
| Australia LNG | 44.5 | LNG | 43,140 BTU | 2.318 m³ | 23.18 m³ |
| USA Sabine Pass LNG | 46.0 | LNG | 44,610 BTU | 2.242 m³ | 22.42 m³ |
| Trinidad LNG | 47.5 | LNG | 46,060 BTU | 2.171 m³ | 21.71 m³ |
BTU/m³ = CV × VCF × 3412.142 ÷ 3.6. Mid-range CV used for ranges. Source: Xoserve, GIIGNL, National Grid 2026. CVs update quarterly — use contract-stated value for commercial accuracy.