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Flow Rate Conversions — l/s, l/min, m³/h
Flow rate unit conversions for UK plumbing, heating and ventilation. Litres per second, litres per minute, cubic metres per hour and gallons per minute.
Flow Rate Conversion Factors
| From | To | Multiply By |
|---|---|---|
| l/s | l/min | 60 |
| l/min | l/s | 0.01667 |
| l/s | m³/h | 3.6 |
| m³/h | l/s | 0.2778 |
| l/min | m³/h | 0.06 |
| l/s | UK gal/min | 13.20 |
| UK gal/min | l/s | 0.07577 |
| l/s | US gal/min | 15.85 |
| US gal/min | l/s | 0.06309 |
Common UK Flow Rates
| Application | l/s | l/min | m³/h |
|---|---|---|---|
| Kitchen tap | 0.10 – 0.25 | 6 – 15 | 0.36 – 0.90 |
| Basin tap | 0.07 – 0.15 | 4 – 9 | 0.24 – 0.54 |
| Standard shower | 0.13 – 0.20 | 8 – 12 | 0.48 – 0.72 |
| Power shower | 0.25 – 0.33 | 15 – 20 | 0.90 – 1.20 |
| Bath fill (taps) | 0.25 – 0.50 | 15 – 30 | 0.90 – 1.80 |
| Combi boiler DHW output | 0.17 – 0.28 | 10 – 17 | 0.60 – 1.02 |
| WC flush (6 litre) | — | ~6 litres per flush | — |
| Washing machine fill | 0.10 – 0.17 | 6 – 10 | 0.36 – 0.60 |
| Garden hose | 0.12 – 0.25 | 7 – 15 | 0.42 – 0.90 |
Ventilation Flow Rates (Air)
| l/s | m³/h | Typical Use |
|---|---|---|
| 6 | 21.6 | WC extract (Part F) |
| 15 | 54 | Bathroom extract (Part F) |
| 30 | 108 | Kitchen extract (adjacent hob) |
| 60 | 216 | Kitchen cooker hood (Part F) |
Related Pages
See the Pressure Unit Conversions, the Water Velocity Standards, and the Ventilation Rates by Room.
Next up: related pages
Frequently Asked Questions
A good shower experience requires 8-12 litres per minute (0.13-0.20 l/s). Below 8 l/min feels weak; above 12 l/min is excellent. Power showers can use 15-20 l/min. Low-flow eco showerheads deliver 6-8 l/min while maintaining a good spray pattern. Mains-pressure (combi or unvented) systems typically deliver 10-15 l/min; gravity-fed systems from a loft tank may deliver only 5-10 l/min without a pump.
A modern combi boiler delivers approximately 10-15 litres per minute of hot water (at a 35°C temperature rise). This is sufficient for one shower or bath fill at a time. Higher-output combi boilers (35-40 kW) can deliver up to 15-17 l/min. If the incoming mains flow rate is less than the boiler output, the mains flow rate becomes the limiting factor — always check mains flow rate before specifying a combi boiler.
The simplest method is to time how long it takes to fill a known container. A standard bucket is approximately 10 litres. If it fills in 40 seconds, the flow rate is 10 ÷ 40 = 0.25 l/s or 15 l/min. For mains flow rate testing, open the kitchen cold tap fully (usually the nearest draw-off to the incoming main) and time the bucket fill. Test at different times of day as mains pressure varies.
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Last updated: April 2026
Verified against UK standards · estimates only, confirm with your supplier.