Borewell Pump HP Calculator
How the formula works
The calculator finds the total head the pump must lift, then the power needed to move the required flow against that head.
Formulas
Static head = Pumping water level + Delivery height
Total head (m) = Static head × (1 + Losses %) + Pressure (bar) × 10.197
Hydraulic power (kW) = Flow (m³/h) × Head (m) × 0.0027241
Motor input power = Hydraulic power / Overall efficiency
Power with margin = Input power × (1 + Margin %)
HP = kW / 0.7457
Where:
- Pumping water level = depth of the water below ground while the pump is running
- Delivery height = height of the tank inlet above ground
- Flow in m³/h = L/min × 0.06
- If you know the daily need: Flow = Daily litres / Running hours / 1000
Typical values
Pipe friction and bend losses: 5 to 20 % of the static head. Overall pump and motor efficiency for borewell submersible pumps: 40 to 55 %. Safety margin: 10 to 20 %. Standard motor sizes: 0.5, 0.75, 1, 1.5, 2, 3, 5, 7.5, 10 HP and above. Current uses a typical power factor of 0.8. These are typical planning values. The pump maker’s curve and the local code are final. Use the Custom option for your own values.
How to use the calculator: choose the method, enter the flow or daily need, enter the water level and delivery height, select losses, efficiency and margin, then click Calculate.
Important notes: the pumping water level is lower than the resting level because the water level drops when you pump (drawdown). Use the lower value. Check the borewell diameter and the yield of the well before you buy.
Worked example
Example 1: Home borewell, flow known
60 L/min (3.6 m³/h), water level 60 m, tank 10 m above ground, losses 10 %, efficiency 45 %, margin 15 %.
Static head = 70 m. Total head = 70 × 1.10 = 77.0 m. Hydraulic power = 0.76 kW. Input = 1.68 kW. With margin = 1.93 kW = 2.59 HP. Recommended: 3 HP.
Example 2: Daily need known
20,000 litres per day pumped in 4 hours (5 m³/h), water level 100 m, tank 12 m, losses 10 %, efficiency 50 %, margin 10 %.
Total head = 112 × 1.10 = 123.2 m. Hydraulic power = 1.68 kW. Input = 3.36 kW. With margin = 3.69 kW = 4.95 HP. Recommended: 5 HP.
Example 3: Feet and pressure
10 US GPM, water level 200 ft, delivery 30 ft, losses 15 %, pressure 2 bar, efficiency 40 %, margin 20 %.
Static head = 70.1 m. Total head = 70.1 × 1.15 + 2 × 10.197 = 101.0 m (331 ft). Input = 1.56 kW. With margin = 1.87 kW = 2.51 HP. Recommended: 3 HP.
Example 4: Farm pump with current
12 m³/h (200 L/min), water level 80 m, delivery 5 m, losses 5 %, efficiency 55 %, margin 15 %, three phase 415 V.
Total head = 89.3 m. Hydraulic power = 2.92 kW. Input = 5.30 kW. With margin = 6.10 kW = 8.18 HP. Recommended: 10 HP. Approx. full load current = 9.2 A.
Common mistakes
- Using the resting water level instead of the lower pumping water level.
- Forgetting the delivery height above ground, so the head is too low.
- Ignoring pipe friction, which is large for long or small-diameter rising mains.
- Choosing the pump only by HP without checking the flow at that head on the pump curve.
- Using an efficiency of 70 % or more, which is too high for most borewell pumps.
- Choosing a pump that is bigger than the well yield, so the pump runs dry.
- Mixing up feet and metres, or GPM and L/min.
- Not allowing for a voltage drop in the long cable to a deep pump.
- Selecting a pump that does not fit in the borewell casing.
Frequently asked questions
How do I calculate borewell pump HP?
Find the total head and the flow, calculate the hydraulic power, divide by the efficiency, add a margin, then convert kW to HP.
What is the formula for pump HP?
HP = Flow (m³/h) × Head (m) × 0.0027241 / (Efficiency × 0.7457).
What is total head?
It is the water level depth plus the delivery height, plus friction losses and any pressure needed at the outlet.
What is the pumping water level?
It is the depth of the water below ground while the pump is running. It is lower than the resting level.
How many HP pump for a 200 ft borewell?
It depends on the flow and the water level. A typical home pump for a 200 ft water level is 1.5 to 3 HP.
What is a good efficiency for a borewell pump?
Overall pump and motor efficiency is usually 40 to 55 %.
Why add a safety margin?
It covers voltage drop, wear and small errors in the head and flow. Ten to 20 % is common.
How do I convert litres per minute to cubic metres per hour?
Multiply L/min by 0.06. For example, 60 L/min is 3.6 m³/h.
What is the difference between a submersible and a jet pump?
A submersible pump works inside the borewell and lifts from great depth. A jet pump sits above ground and suits shallow water levels.
Can I use this for an open well?
Yes, enter the water level below ground. For a shallow well a surface pump may be more suitable.
How do I size the tank?
Use the Water Tank Size Calculator and the Daily Water Demand Calculator for your water need.
Is this a final pump selection?
No. It is a planning estimate. Always check the pump maker’s curve and the well yield before buying.