Understanding Volume Flow Rate
Volume flow rate measures how much space a fluid occupies over time. In the imperial system you may see it expressed as cubic yards per hour (yd³/h). In the metric system the same idea appears as litres per year (l/a). Both belong to the same parent measure, so they can be directly related.
What is a Cubic Yard per Hour (yd³/h)?
A cubic yard is a cube with each side equal to one yard (0.9144 m). One cubic yard holds about 764.5549 litres. When we say “per hour,” we are tracking how many of those cubes pass a point each hour.
What is a Litre per Year (l/a)?
A litre is a metric unit equal to one cubic decimetre (0.001 m³). “Per year” spreads that volume over 365 days, or 8 760 hours. It is useful for long‑term planning, such as water‑usage contracts or industrial discharge limits.
Conversion Factor Explained
The exact factor that links the two units is:
1 yd³/h = 6,697,500.5559 l/a
This number comes from two steps: converting cubic yards to litres, then scaling hours to a full year.
How to Convert: Step‑by‑Step Formula
- Convert cubic yards to litres: 1 yd³ = 764.554857984 L.
- Convert hours to years: 1 year = 8,760 hours.
- Multiply the two results: L × hours = litres per year.
In formula form:
value (l/a) = value (yd³/h) × 764.554857984 × 8,760
Worked Example: Converting 3 yd³/h to l/a
Start with the source flow: 3 yd³/h.
Step 1 – Convert to litres per hour:
3 × 764.554857984 = 2,293.664573952 L/h
Step 2 – Scale to a year:
2,293.664573952 L/h × 8,760 h/a = 20,092,501.6678 l/a
Rounded to four decimal places, 3 yd³/h equals 20,092,501.6678 l/a. The same method works for any value.
Cubic Yards per Hour to Litres per Year Conversion Table
Each row applies the same rule: multiply the cubic yards per hour by 6,697,500.5559 to obtain litres per year. Values are rounded to four decimal places where needed.
| Cubic Yards per Hour (yd³/h) | Litres per Year (l/a) |
|---|---|
| 1 yd³/h | 6,697,500.5559 l/a |
| 2 yd³/h | 13,395,001.1118 l/a |
| 5 yd³/h | 33,487,502.7795 l/a |
| 10 yd³/h | 66,975,005.5590 l/a |
| 20 yd³/h | 133,950,011.1180 l/a |
| 50 yd³/h | 334,875,027.7950 l/a |
| 100 yd³/h | 669,750,055.5900 l/a |
| 500 yd³/h | 3,348,750,277.9500 l/a |
Practical Applications
- Water‑resource planning: Engineers can translate short‑term pump rates (yd³/h) into annual consumption (l/a) for budgeting.
- Environmental compliance: Discharge permits often require yearly limits; converting hourly flow helps verify compliance.
- Construction logistics: Estimating concrete delivery over a project year becomes straightforward when you start with a yard‑per‑hour mixer rate.
Key Takeaway
One cubic yard per hour equals roughly 6.7 million litres per year. Use the simple multiplication shown above to move between these units instantly.
Ready to apply this conversion to your own data? Plug your flow rate into the formula and see the annual impact in seconds.