Conversion Formula
L/s to CFM: CFM = L/s × 2.11888
Quick check: 100 CFM ≈ 47.2 L/s
CFM to L/s Quick Reference Table
| CFM | L/s | CFM | L/s |
|---|---|---|---|
| 10 | 4.7 | 150 | 70.8 |
| 21 | 9.9 | 200 | 94.4 |
| 25 | 11.8 | 250 | 118.0 |
| 50 | 23.6 | 300 | 141.6 |
| 53 | 25.0 | 350 | 165.2 |
| 75 | 35.4 | 400 | 188.8 |
| 100 | 47.2 | 500 | 236.0 |
| 125 | 59.0 | 750 | 354.0 |
Bathroom Exhaust Fan Reference (Canada)
| Fan Rating | CFM | L/s | Typical Application |
|---|---|---|---|
| Minimum continuous | 21 CFM | 10 L/s | Continuous whole-home ventilation contribution |
| Standard bathroom fan | 50 - 80 CFM | 24 - 38 L/s | Common residential half or full bath |
| Boost / intermittent rate | 53 - 106 CFM | 25 - 50 L/s | Switch or humidity-sensor triggered |
| Large bathroom / ensuite | 100 - 150 CFM | 47 - 71 L/s | Master ensuite with separate shower/tub |
| Powder room | 50 CFM | 24 L/s | Minimum viable exhaust |
Kitchen Range Hood Reference (Canada)
| Cooktop Type | CFM | L/s | Notes |
|---|---|---|---|
| Standard electric cooktop | 53 - 100 CFM | 25 - 47 L/s | Basic code minimum range |
| Standard gas cooktop | 100 - 150 CFM | 47 - 71 L/s | Higher due to combustion byproducts |
| High-output gas range | 300 - 600 CFM | 142 - 283 L/s | May trigger makeup air requirement |
| Commercial-style range | 600 - 1200 CFM | 283 - 566 L/s | Requires dedicated makeup air system |
Values are general reference ranges. Always verify current requirements with your local building authority and product certification labels. Use the Airflow Unit Converter for full multi-unit conversion including m³/h and ACH.
How to Use the CFM to L/s Converter
Type a CFM value or an L/s value -- the other field updates instantly. Use the quick presets for common Canadian ventilation code reference points: the 10 L/s minimum continuous rate, 25 L/s kitchen minimum, or a standard 50 CFM bathroom fan.
The result panel identifies what fixture or application your converted airflow rate typically matches: bathroom exhaust, kitchen hood, whole-home ventilation, or larger equipment airflow. This helps quickly cross-check a fan nameplate rating against a code requirement.
The quick reference table covers 10 to 750 CFM in one glance. The bathroom fan and kitchen hood tables show typical CFM and L/s ranges by fixture type so you can quickly verify a product's rated airflow meets or exceeds the applicable minimum.
For airflow conversions beyond CFM and L/s -- including m³/h, m³/s, CMM, and a built-in ACH calculator from room dimensions -- use the Airflow Unit Converter. For duct velocity and system design, see the Duct Sizing Calculator.
CFM and L/s in Canadian Residential HVAC
Canadian residential ventilation work involves a constant back-and-forth between CFM and L/s. Bathroom fans, range hoods, and HRV/ERV units are manufactured to North American standards and labelled in CFM, but Canadian building codes and provincial ventilation requirements are written in litres per second, reflecting Canada's metric system for building science and code documentation.
The Conversion: 0.4719
The exact factor is 1 CFM = 0.47195 L/s. For quick mental math, a close approximation is to divide CFM roughly in half: 100 CFM is close to 50 L/s (actual value 47.2 L/s), and 50 CFM is close to 25 L/s (actual value 23.6 L/s). For precise code compliance checks, always use the exact conversion rather than the rough approximation, since minimum ventilation rates in building codes are specific thresholds. The exact factor traces back to the litre-to-cubic-foot relationship set out in the NIST Guide to the SI, Appendix B.
Bathroom and Kitchen Exhaust Sizing
Residential exhaust fan selection starts with the code-required minimum flow rate in L/s, then requires finding a fan model rated in CFM that meets or exceeds that requirement once converted. A fan rated at 50 CFM delivers 23.6 L/s -- sufficient for most standard bathroom minimums but potentially short of a higher kitchen hood requirement, which commonly calls for 25 L/s (53 CFM) or more. Always check the fan's sone rating (noise level) alongside CFM, since a fan that's too loud often gets switched off by occupants, defeating its ventilation purpose regardless of its rated capacity. The Exhaust Fan Sizing Calculator walks through both the flow rate and duct sizing side of the selection.
HRV and ERV Sizing
Heat recovery ventilators (HRV) and energy recovery ventilators (ERV) are the primary whole-home mechanical ventilation systems in new Canadian construction. Unit capacity is typically shown in CFM on North American product labels, while the required continuous ventilation rate for a home is calculated in L/s based on floor area and bedroom count under applicable residential ventilation standards. Converting the HRV's rated CFM to L/s lets you compare directly against the calculated whole-home requirement from the HRV Ventilation Calculator. Use the Airflow Unit Converter for the full multi-unit conversion including whole-home rate calculations.
Why the Dual System Persists
Despite Canada's official metric adoption, HVAC equipment manufacturing remains overwhelmingly North American in scale, with most residential ventilation products designed and rated primarily for the US market in CFM. Canadian distributors and contractors work daily with CFM-labelled equipment against L/s-based code requirements. This is unlikely to change soon, making fluent CFM-to-L/s conversion an essential everyday skill for anyone working in Canadian residential ventilation. The National Building Code of Canada, published by the National Research Council, sets out all of its requirements in metric units.
Frequently Asked Questions
Multiply CFM by 0.4719 to get L/s. So 50 CFM = 23.6 L/s, and 100 CFM = 47.2 L/s. To convert L/s back to CFM, multiply by 2.119. This is the most frequent airflow conversion in Canadian residential HVAC since bathroom fans, range hoods, and HRVs are labelled in CFM but code requirements are specified in L/s.
Common minimum bathroom exhaust requirements in Canada are around 10 L/s (21 CFM) for continuous operation, with higher intermittent rates -- often 25 to 50 L/s (53 to 106 CFM) -- for switch or sensor-triggered boost ventilation. Requirements vary by province and code edition, so always verify current requirements for your specific jurisdiction before selecting a fan model.
Standard kitchen exhaust requirements commonly reference around 25 L/s (53 CFM) minimum intermittent rate for typical cooktops. Higher-output gas ranges and commercial-style cooktops require significantly more airflow, sometimes 300 CFM or more, which can trigger a dedicated makeup air requirement under many provincial codes. Always check current local code requirements and the range hood's actual rated CFM at the installed static pressure.
Most residential ventilation equipment -- bathroom fans, range hoods, HRVs -- is manufactured to North American standards and labelled in CFM, while Canadian building codes and engineering specifications use L/s following Canada's metric system. Contractors and technicians routinely convert between the two when comparing product nameplates against code-required minimums. This dual-unit reality is a permanent feature of Canadian HVAC practice rather than a temporary transition.