Curve Number Calculator

✖Potential Maximum Retention (Curve Number) depends upon the soil vegetation land use complex of the catchment and also upon the antecedent soil moisture condition.ⓘ Potential Maximum Retention (Curve Number) [S_CN]

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✖Curve Number is based on the area's hydrologic soil group, land use , treatment and hydrologic condition.ⓘ Curve Number [CN]

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Formula

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Curve Number

Formula

`"CN" = 25400/("S"_{"CN"}+254)`

Example

`"12.00378"=25400/("1862mm"+254)`

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Download SCS-CN Method of Runoff Volume Formulas PDF

Curve Number Solution

STEP 0: Pre-Calculation Summary

Formula Used

Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254)
CN = 25400/(S_CN+254)
This formula uses 2 Variables

Variables Used

Curve Number - Curve Number is based on the area's hydrologic soil group, land use , treatment and hydrologic condition.
Potential Maximum Retention (Curve Number) - (Measured in Millimeter) - Potential Maximum Retention (Curve Number) depends upon the soil vegetation land use complex of the catchment and also upon the antecedent soil moisture condition.

STEP 1: Convert Input(s) to Base Unit

Potential Maximum Retention (Curve Number): 1862 Millimeter --> 1862 Millimeter No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

CN = 25400/(S_CN+254) --> 25400/(1862+254)

Evaluating ... ...

CN = 12.0037807183365

STEP 3: Convert Result to Output's Unit

12.0037807183365 --> No Conversion Required

FINAL ANSWER

12.0037807183365 ≈ 12.00378 <-- Curve Number

(Calculation completed in 00.004 seconds)

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Home » Engineering » Civil » Engineering Hydrology » Runoff » Runoff Volume » SCS-CN Method of Runoff Volume » Curve Number (CN) » Curve Number

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Created by Ayush Singh

Gautam Buddha University (GBU), Greater Noida

Ayush Singh has created this Calculator and 50+ more calculators!

Verified by Mithila Muthamma PA

Coorg Institute of Technology (CIT), Coorg

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< 5 Curve Number (CN) Calculators

Curve Number for Antecedent Moisture Condition One

Go Curve Number = Runoff Curve Number/(2.281-0.01281*Runoff Curve Number)

Curve Number for Antecedent Moisture Condition-III

Go Curve Number = Runoff Curve Number/(0.427+0.00573*Runoff Curve Number)

Potential Maximum Retention given Curve Number

Go Potential Maximum Retention (Curve Number) = 254*(100/Curve Number-1)

Potential Maximum Retention

Go Potential Maximum Retention (Curve Number) = (25400/Curve Number)-254

Curve Number

Go Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254)

Curve Number Formula

Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254)
CN = 25400/(S_CN+254)

What is Runoff Curve Number?

The Runoff curve number is an empirical parameter used in hydrology for predicting direct runoff or infiltration from rainfall excess. The curve number is based on the area's hydrologic soil group, land use, treatment and hydrologic condition.

What is Curve Number and on what factors it depends?

The Curve Number (CN) is a dimensionless parameter related to the potential maximum retention expressed in millimeters. It ranges from 0-100. A CN value of 100 represents a condition of zero potential retention and CN= 0 represents an infinitely abstracting catchment with S= ∞.
The Curve Number CN depends upon the following listed below
1. Soil Type
2. Land Use/Cover
3. Antecedent moisture condition

How to Calculate Curve Number?

Curve Number calculator uses Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254) to calculate the Curve Number, The Curve Number formula is defined as the ratio of the constant 25400 to the potential maximum retention expressed in millimeters. Curve Number is denoted by CN symbol.

How to calculate Curve Number using this online calculator? To use this online calculator for Curve Number, enter Potential Maximum Retention (Curve Number) (S_CN) and hit the calculate button. Here is how the Curve Number calculation can be explained with given input values -> 12.00378 = 25400/(1.862+254).

FAQ

What is Curve Number?

The Curve Number formula is defined as the ratio of the constant 25400 to the potential maximum retention expressed in millimeters and is represented as CN = 25400/(S_CN+254) or Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254). Potential Maximum Retention (Curve Number) depends upon the soil vegetation land use complex of the catchment and also upon the antecedent soil moisture condition.

How to calculate Curve Number?

The Curve Number formula is defined as the ratio of the constant 25400 to the potential maximum retention expressed in millimeters is calculated using Curve Number = 25400/(Potential Maximum Retention (Curve Number)+254). To calculate Curve Number, you need Potential Maximum Retention (Curve Number) (S_CN). With our tool, you need to enter the respective value for Potential Maximum Retention (Curve Number) and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

How many ways are there to calculate Curve Number?

In this formula, Curve Number uses Potential Maximum Retention (Curve Number). We can use 2 other way(s) to calculate the same, which is/are as follows -

Curve Number = Runoff Curve Number/(2.281-0.01281*Runoff Curve Number)
Curve Number = Runoff Curve Number/(0.427+0.00573*Runoff Curve Number)

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