Converter · 1 CFM = 0.4719 L/s
CFM to L/s converter
Airflow across unit systems — with ACH from room size, CFM/ton, and fixture context so a nameplate check takes seconds. Type in any field; everything updates.
Last updated: October 2026
Converter · 1 CFM = 0.4719 L/s
CFM ↔ L/s ↔ m³/h
Type in any field — all units update. Optional ACH from room size.
Quick presets
ACH: —
CFM to L/s — formula and ventilation context
1 foot = 0.3048 m exactly (1959 international yard). Therefore 1 CFM = 28.3168 L ÷ 60 s = 0.471947 L/s, and 1 CFM = 1.699 m³/h. Reverse: 1 L/s = 2.119 CFM, 1 m³/h = 0.5886 CFM. Mental shortcut: halve the CFM and subtract ~5% (100 CFM ≈ 47 L/s actual 47.2).
Why this conversion never goes away
North American fans, hoods, and HRVs are labelled in CFM; Canadian codes (NBC) and international standards (ISO 16890, EN 16798) specify ventilation in L/s. A 50 CFM bath fan delivers 23.6 L/s; a 25 L/s kitchen minimum needs a 53 CFM hood. The fixture badges above flag these thresholds so a nameplate check takes seconds. For full duct design, carry the CFM into theduct-sizing calculator (Manual D).
ACH from room size
ACH = (CFM × 60) ÷ room ft³. Enter length, width, and ceiling height above for the exact air-changes rate — offices target 4–6 ACH, labs 6–12, cleanrooms 20+. At 400 CFM/ton, a 3-ton system moves ~1,200 CFM through the trunk.
FAQ
Airflow conversion questions, answered
How do I convert CFM to L/s?
Multiply CFM by 0.4719. To go back, multiply L/s by 2.119. A 100 CFM fan delivers 47.2 L/s. For m³/h, multiply CFM by 1.699.
What ACH do I need for a bathroom?
Continuous whole-home ventilation contributes about 10 L/s (21 CFM) per NBC. Intermittent bath fans are typically 50–80 CFM. Enter room dimensions above for the exact ACH of your fan.
How many CFM per ton of cooling?
About 400 CFM per ton — 350 in humid climates, up to 450 in dry ones. A 3-ton system moves roughly 1,200 CFM through the supply trunk.
What is the difference between CFM, L/s, and m³/h?
Same quantity (volumetric airflow), different units. CFM is standard on North American equipment, L/s on Canadian/international specs, m³/h on European equipment. 1 CFM = 0.472 L/s = 1.699 m³/h.
Does this converter work offline?
Yes. FieldCalc is an installable PWA — after your first visit, this converter runs with zero signal. All math stays on your device.
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