Cubic Meters/Day to Litres/Second Converter – cmd to l/s

Online calculator for converting volumetric flow from cubic metres per day (m³/d; also m3/d, m^3/day, cmd) to litres per second (L/s; also l/s). Legitimacy: factors are exact under SI—1 L = 10⁻³ m³ and 1 day = 86 400 s—so results are reproducible and standard-compliant.

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How to use

1. Enter a flow value in m³/d in the input field.
2. Click Convert to compute L/s.
3. Set Decimal Places (0–10) to control rounding of the displayed result (calculation remains exact).
4. Use Copy to put the result on your clipboard.
5. Use Swap to open the reverse tool (L/s → m³/d).
6. Click Clear to reset inputs, output, and the calculation line.

Definitions of measurement units

Cubic metre per day (m³/d) — a flow unit derived from the cubic metre (m³), the base SI unit of volume. It measures the volume of one cubic metre passing through a system in 24 hours. Abbreviations include m³/d, m3/d, m3/day, and cmd. System: SI (derived). Exact relation in this conversion: 1 m³/d = 0.011574 L/s. In another SI unit of time, 1 m³/d = 1000 litres per 86 400 seconds. Typical uses: water treatment plant capacity, municipal water supply planning, and industrial process outputs expressed per day.

Litre per second (L/s) — a unit of flow rate accepted for use with the SI, based on the litre (L), where 1 L = 0.001 m³. It indicates the number of litres moving each second. Abbreviations: L/s, l/s. System: SI-compatible. Exact relation in this conversion: 1 L/s = 86.4 m³/d. In relation to Imperial/US customary units, 1 L/s ≈ 15.8503 US gallons per minute (gpm). Typical uses: firefighting flow ratings, pump and pipe sizing, HVAC and irrigation design, and instantaneous hydraulic performance tests.

Conversion formula

L/s = (m³/d) × 1000 ÷ 86 400 = (m³/d) ÷ 86.4

m³/d = (L/s) × 86.4

Source: BIPM — The International System of Units (SI), 9th edition (exact definitions: litre as 10⁻³ m³ and day as 86 400 s).

Conversion table (m³/d → L/s)

Real-world, exact-rating examples

• Water meter (ISO 4064) Q3 2.5 m³/h: 60 m³/d = 0.69444 L/s
• Water meter (ISO 4064) Q3 4.0 m³/h: 96 m³/d = 1.11111 L/s
• Water meter (ISO 4064) Q3 6.3 m³/h: 151.2 m³/d = 1.75 L/s
• Water meter (ISO 4064) Q3 10 m³/h: 240 m³/d = 2.77778 L/s
• Water meter (ISO 4064) Q3 16 m³/h: 384 m³/d = 4.44444 L/s
• Fire pump (EN 1028) FPN 10-1000: 1 440 m³/d = 16.6667 L/s (1000 L/min)
• Fire pump (EN 1028) FPN 10-1500: 2 160 m³/d = 25.0 L/s (1500 L/min)
• Fire pump (EN 1028) FPN 10-2000: 2 880 m³/d = 33.3333 L/s (2000 L/min)
• Fire pump (EN 1028) FPN 10-3000: 4 320 m³/d = 50.0 L/s (3000 L/min)
• Large water meter (ISO 4064) Q3 25 m³/h: 600 m³/d = 6.94444 L/s

What’s your use case for this calculator, and what would you like added (e.g., batch conversion, unit mixing, copy as CSV)? Tell us in the comments.

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