# Fuel Pump Calculator

URL: https://speedycalculator.com/calculators/everyday-life/fuel-pump/
Last updated: 2026-10-25

> The fuel pump calculator estimates the fuel flow a pump must deliver for a target horsepower, induction type and fuel, and the pressure it must hold for return and returnless systems.

## Inputs

- Target horsepower (hp)
- Induction
- Fuel
- Base fuel pressure (psi, bar, kPa)
- Maximum boost (psi, bar, kPa)
- Fuel system

## Results

- Required flow
- Flow with 25% safety margin
- Pump must deliver it at

## Formula

```
Flow (L/h) ≈ hp × 0.3735 (naturally aspirated), × 0.415 (turbo), × 0.498 (supercharged)
× fuel factor (E30 1.1, E85 1.4, methanol 2.2)
Pump pressure = base pressure + boost (return system)
```

## Explanation

A fuel pump's rated flow drops as the pressure it pushes against rises, so choose a pump that meets the flow at your running pressure – including boost on a return-style system with a 1:1 regulator – with a 20–30% safety margin.

### How to use the Fuel Pump Calculator

- **Target horsepower**
- **Induction**
- **Fuel**
- **Base fuel pressure**
- **Maximum boost**
- **Fuel system**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the target horsepower, induction type, fuel, base fuel pressure and maximum boost, and choose the fuel system type.

### Tips

- Use your own measured figures – fuel economy, speed and prices vary a lot with driving style, traffic, load and season.
- Pick the unit in each field's menu (miles or kilometres, mpg or L/100 km); the calculator converts everything for you.
- Fill up to the brim twice and divide the distance by the fuel added to measure real fuel economy.
- For vehicle modifications, treat results as a starting point and confirm with the parts maker or a professional mechanic.

### Common mistakes to avoid

- Mixing US and imperial (UK) gallons – a UK gallon is about 20% bigger.
- Using the advertised fuel economy instead of real-world figures.
- Forgetting tolls, parking and wear and tear when comparing driving with public transport.

### Inputs explained

FieldWhat to enterTarget horsepowerIn hpInductionChoose one: Naturally aspirated, Turbocharged, SuperchargedFuelChoose one: Petrol, E30, E85, MethanolBase fuel pressureUnits: psi, bar, kPaMaximum boostUnits: psi, bar, kPaFuel systemChoose one: Return (1:1 regulator), Returnless

### What each result means

- **Required flow** = [Target horsepower]×[Induction]×[Fuel]
- **Flow with 25% safety margin** = [Required flow]×1.25
- **Pump must deliver it at** = [Base fuel pressure] + [Fuel system]×[Maximum boost]

### Example values

How the main result changes when **Target horsepower** changes and everything else stays at the example values above:

Target horsepower (hp)Required flow (L/h)22593337.5140450187562.5233675280900374

## Worked example

Inputs — Target horsepower: 450 hp; Induction: Turbocharged; Fuel: Petrol; Base fuel pressure: 43.5 psi; Maximum boost: 15 psi; Fuel system: Return (1:1 regulator).

Results — **Required flow = 187 L/h**; Flow with 25% safety margin = 233 L/h; Pump must deliver it at = 58.5 psi.

## FAQ

**What fuel pump do I need for 500 hp?**
About 190–250 L/h for petrol depending on induction, delivered at your running pressure.

**Why does boost raise the pressure requirement?**
On a return system the regulator raises fuel pressure 1:1 with boost so injector flow stays consistent.

**Do I need a bigger pump for E85?**
Yes – about 30–40% more flow than petrol for the same power.

**What formula does the Fuel Pump Calculator use?**
Flow (L/h) ≈ hp × 0.3735 (naturally aspirated), × 0.415 (turbo), × 0.498 (supercharged).