Hydraulic Jump Calculator
Calculate conjugate depth and ideal specific-energy loss across a rectangular-channel hydraulic jump.
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Result
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Calculation steps
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How to calculate
Use rectangular-channel momentum balance and require an initially supercritical stream.
Fr1=v1/√(g y1); y2/y1=(√(1+8Fr1²)−1)/2; loss=(y2−y1)³/(4 y1 y2)
Worked example
At Froude number two, conjugate-depth ratio is (√33−1)/2≈2.37228132. The downstream state is subcritical.
Assumptions and input details
Horizontal prismatic rectangular channel, hydrostatic sections, no bed friction through the short jump and momentum/energy correction factors one. This gives conjugate depths, not actual jump position, roller length or structural design loads.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
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