Room volume feeds into ACH calculations. Use the Airflow Unit Converter for ACH from airflow rate and room volume.
Key Conversion Factors
1 ft³ = 28.3168 L = 0.028317 m³ = 7.4805 US gal
1 US gal = 3.78541 L = 0.13368 ft³ = 0.8327 Imp. gal
1 Imp. gal = 4.54609 L = 0.16054 ft³ = 1.20095 US gal
1 in³ = 16.3871 cm³ = 16.3871 mL = 0.016387 L
HVAC Tank and System Volume Reference
| Component / Application | Typical Volume (L) | Typical Volume (US gal) | Notes |
|---|---|---|---|
| Residential hot water tank (small) | 150 - 190 | 40 - 50 | Small household, 1-2 persons |
| Residential hot water tank (standard) | 190 - 270 | 50 - 71 | Most common Canadian size |
| Residential hot water tank (large) | 270 - 380 | 71 - 100 | Large family or high-demand |
| Hydronic expansion tank (residential) | 8 - 20 | 2 - 5 | Bladder-type for closed loop |
| Hydronic expansion tank (commercial) | 50 - 500 | 13 - 132 | Larger closed-loop systems |
| Chilled water buffer tank | 200 - 2000 | 53 - 528 | Thermal flywheel for chiller cycling |
| Propane tank (residential small) | 420 | 111 | 100 US gal tank (standard industry sizing); ~80% fill = 336 L LPG |
| Propane tank (residential standard) | 1000 | 264 | Common rural Canadian heating tank |
| Refrigerant recovery cylinder (30 lb) | 27 | 7.1 | Standard recovery tank capacity |
| Refrigerant cylinder (R-410A, 11.3 kg) | ~14 | ~3.7 | Standard disposable cylinder |
| Condensate drain pan (residential) | 0.5 - 2 | 0.13 - 0.53 | Overflow detection pan capacity |
Typical Room Volumes -- Canadian Construction
| Room Type | Typical Dimensions | Volume (m³) | Volume (ft³) |
|---|---|---|---|
| Bathroom | 2.4 x 1.8 x 2.44 m | 10.5 | 372 |
| Bedroom (small) | 3.0 x 3.0 x 2.44 m | 22.0 | 777 |
| Bedroom (standard) | 3.7 x 3.4 x 2.44 m | 30.7 | 1085 |
| Living room (small home) | 4.6 x 4.0 x 2.44 m | 44.9 | 1586 |
| Open concept living/kitchen | 7.0 x 5.5 x 2.44 m | 94.0 | 3320 |
| Basement (unfinished) | 10 x 8 x 2.13 m | 170 | 6003 |
| Small office (single occupant) | 3.0 x 3.7 x 2.74 m | 30.4 | 1074 |
| Conference room (8-10 pax) | 5.5 x 4.0 x 2.74 m | 60.3 | 2130 |
| Retail floor (small shop) | 10 x 8 x 3.0 m | 240 | 8476 |
How to Use the Volume Converter
Type a volume in m³, litres, ft³, in³, US gallons, Imperial gallons, or cm³. All other units update instantly. Use the quick presets for common HVAC volumes: standard hot water tank (270 L), expansion tank (100 L), or room volume for ACH calculations (50 m³).
Enter room length, width, and height in metres in the Room Volume Calculator. Volume in m³, ft³, and litres display instantly. The result populates the main converter so you can see all units at once. Use the room volume with the Airflow Unit Converter to calculate air changes per hour (ACH) for ventilation design.
The result panel identifies what HVAC application your volume corresponds to: small fitting or pipe section, residential tank, room or plenum volume, or large commercial system. This helps catch order-of-magnitude errors -- a 270 m³ hot water tank rather than 270 L is immediately flagged as anomalous.
Always verify which gallon is specified on US equipment datasheets versus Canadian specs. A US gallon is 3.785 L; an Imperial gallon is 4.546 L -- about 20% larger. A hot water tank labelled "50 US gallon" holds 189.3 L, not the 227.3 L that a 50 Imperial gallon tank would hold. The converter shows both simultaneously so you can confirm the correct interpretation before specifying or ordering equipment.
Volume Units in HVAC -- Complete Guide
Volume measurements in HVAC span a wide range of applications: from the internal volume of refrigerant piping (measured in litres or cubic centimetres) to room volumes for ventilation calculations (cubic metres) to tank sizing (litres or gallons) to duct system volumes (cubic feet or cubic metres). Canadian HVAC uses metric for most engineering work but US equipment specs commonly use cubic feet and gallons, with reference methods for these calculations published in the ASHRAE Handbook -- Fundamentals.
Litres and Cubic Metres -- The Canadian Standard
The litre (L) is the standard volume unit for Canadian fluid and tank specifications. 1 litre = 0.001 m³ = 1 dm³. Hot water tanks in Canada are sold in litres: 190 L, 270 L, and 380 L are the most common residential sizes. Hydronic system volumes, expansion tank sizing, and chiller buffer tank capacities all use litres. For larger volumes, cubic metres apply: a 50 m³ room holds 50 000 litres of air. The conversion: 1 m³ = 1000 L = 35.315 ft³ = 264.17 US gallons, using the exact factors set out in the NIST Guide to the SI, Appendix B.
US Gallons vs. Imperial Gallons in Canadian HVAC
A US gallon equals 3.78541 litres. A Canadian and British Imperial gallon equals 4.54609 litres -- 20.1% larger. This distinction matters when ordering propane tanks, water heaters, or expansion tanks from US suppliers. A propane tank labelled "100 US gallon" holds 378.5 litres, while a "100 Imperial gallon" tank holds 454.6 litres. Canadian propane is commonly sold by the litre or by the "pound" weight of LPG. Always confirm the gallon standard when working with US-sourced equipment in Canadian applications.
Room Volume and ACH Calculations
Air changes per hour (ACH) requires room volume in m³ and airflow in m³/h: ACH = airflow (m³/h) / room volume (m³). A 50 m³ conference room needing 8 ACH requires 50 x 8 = 400 m³/h of air supply. Converting to L/s: 400 m³/h / 3.6 = 111 L/s. Converting to CFM: 111 x 2.119 = 235 CFM. The room volume calculator above handles the geometry, and the Airflow Unit Converter handles the full ACH calculation with all unit conversions. For whole-home ventilation sizing based on total conditioned volume, use the HRV Ventilation Calculator.
Volume in Refrigerant Work
Refrigerant line set internal volume matters for oil return analysis and for estimating charge quantities in large systems. A 20-metre run of 7/8-inch ACR copper suction line (internal diameter approximately 20.6 mm) has volume = pi x (0.0103)² x 20 = 0.00668 m³ = 6.68 litres. This volume of liquid refrigerant at operating density helps estimate the charge that stays in the suction line versus the evaporator and condenser. Refrigerant recovery cylinders are sized by weight (kg) but their rated capacity is also shown in volume (litres) on the cylinder label for reference, a relationship the Charge Weight Calculator works through directly.
Frequently Asked Questions
Multiply cubic feet by 28.3168 to get litres. So 1 ft³ = 28.32 L, 10 ft³ = 283.2 L, and 100 ft³ = 2832 L. To go the other way, divide litres by 28.3168. This conversion is common in HVAC for room volume calculations where US floor plans show dimensions in feet but ventilation calculations need m³ or litres, and for equipment tank capacities where US specs use gallons but Canadian engineering uses litres.
A US gallon equals 3.785 litres. A Canadian/Imperial gallon equals 4.546 litres -- about 20% larger. A "50 US gallon" hot water tank holds 189.3 L; a "50 Imperial gallon" tank holds 227.3 L. Always check which gallon is specified on US equipment datasheets versus Canadian specifications. When in doubt, look for the litre equivalent -- most Canadian equipment labels show litres. The converter above shows both US and Imperial gallons simultaneously for direct comparison.
Room volume (m³) = length (m) x width (m) x ceiling height (m). A 5 x 4 m room with 2.44 m (8 ft) ceiling = 48.8 m³. ACH = airflow in m³/h divided by room volume in m³. For ACH 6 in a 48.8 m³ room: airflow = 6 x 48.8 = 292.8 m³/h = 81.3 L/s = 172 CFM. Use the Room Volume Calculator above to calculate volume from dimensions, then feed it into the Airflow Unit Converter for a complete ACH calculation.
Refrigerant charge is specified by weight (kg), not volume, because density varies with temperature and phase. However, pipe and heat exchanger internal volumes are calculated to estimate charge quantities in large systems or for oil return analysis. Copper tube volume = pi x (ID/2)² x length. For 10 m of 7/8-inch ACR copper (ID approximately 20.6 mm): pi x (0.0103)² x 10 = 3.34 L. Multiply by liquid refrigerant density (approximately 1000-1200 kg/m³ depending on refrigerant and temperature) to estimate the liquid charge in that section of line.