TDH Calculator Online: Calculate Total Dynamic Head for Pump Sizing Instantly

Online TDH Calculator for Pump Sizing

Calculating Total Dynamic Head (TDH) is the most critical step in pump sizing. This guide shows you exactly how to calculate TDH and introduces a tool that does it automatically.

TDH Formula

TDH = Static Head + Friction Losses + Fitting Losses + Residual Pressure

What You Need to Calculate TDH

Input Data Required:

1. Suction elevation (m or ft)
2. Discharge elevation (m or ft)
3. Pipe material (PVC, steel, copper, etc.)
4. Pipe diameter (mm or inches)
5. Pipe length per segment (m or ft)
6. Flow rate (L/s, m³/h, or GPM)
7. Fittings (elbows, valves, tees — type and quantity)
8. Required pressure at destination (m or psi, if any)

What the Calculator Outputs:

• Static head (m)
• Friction losses per segment (m)
• Fitting losses per segment (m)
• Total TDH (m)
• Recommended TDH with safety factor (m)
• Required pump power (HP/kW)
• Fluid velocity per segment (m/s)

Quick TDH Calculation Example

System: Ground-level pump → rooftop tank 18 m above. 35 m of 2" PVC pipe. 3 elbows, 1 check valve, 1 foot valve. Flow: 2 L/s.

Static head: 18 m
Velocity: V = 0.002 / (π×0.0525²/4) = 0.924 m/s
Friction (H-W, C=150): hf = 10.67 × 35 × 0.002^1.852 / (150^1.852 × 0.0525^4.87) = 1.8 m
Fittings: K = 3×0.30 + 2.50 + 2.50 = 5.90
hm = 5.90 × 0.924²/(2×9.81) = 0.26 m

TDH = 18 + 1.8 + 0.26 = 20.06 m
With 15% safety: TDH = 23.1 m

You need a pump that delivers 2 L/s at 23 m head.

Why Manual TDH Calculation Is Risky

1. One wrong K value changes TDH by 5-15%
2. Forgetting the foot valve (K=2.5) underestimates TDH significantly
3. Using wrong pipe ID (nominal vs actual) affects velocity and all downstream calculations
4. Not applying safety factor means the pump barely works on day 1 and fails as pipes age

Use HydroApp Pro as Your TDH Calculator

Instead of calculating manually, use HydroApp Pro:

1. Enter pipe segments (material, diameter, length, elevation)
2. Add fittings from the built-in database
3. Set flow rate
4. Get instant TDH with full breakdown

The app calculates friction using both Darcy-Weisbach and Hazen-Williams, determines the flow regime automatically, and applies the correct friction factor. Results update in real time as you change inputs.

Bonus: enter the pump curve and get the operating point, NPSH analysis, and a professional PDF report — all from the same tool.

Try HydroApp Pro — your online TDH calculator. $99 one-time, permanent access.

Related Calculators

• Pipe friction loss guide
• Reynolds number calculator
• NPSH calculation guide
• Pump sizing guide