# Water Pressure at Depth Calculator

URL: https://speedycalculator.com/calculators/physics/water-pressure-at-depth/
Last updated: 2026-10-30

> The water pressure at depth calculator finds the gauge and absolute pressure at a depth in fresh or salt water – for diving, tanks and submarines.

## Inputs

- Water type
- Depth (m, ft, km)
- Surface pressure (kPa, Pa, bar, psi, atm, MPa)

## Results

- Gauge pressure
- Absolute pressure
- Atmospheres absolute (ATA)

## Formula

```
p_gauge = ρ·g·h,  p_abs = p_atm + ρ·g·h
```

## Explanation

Every 10 m of seawater adds about one atmosphere of pressure. At the bottom of the Mariana Trench, nearly 11 km down, the pressure exceeds 1,000 atmospheres.

### How to use the Water Pressure at Depth Calculator

- **Water type**
- **Depth**
- **Surface pressure**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Choose fresh or salt water and enter the depth.

### Inputs explained

FieldWhat to enterWater typeChoose one: Seawater, Fresh waterDepthUnits: m, ft, kmSurface pressureUnits: kPa, Pa, bar, psi, atm, MPa

### What each result means

- **Gauge pressure** = [Water type]×9.80665×[Depth]
- **Absolute pressure** = [Surface pressure] + [Water type]×9.80665×[Depth]
- **Atmospheres absolute (ATA)** = [Absolute pressure]÷101325

### Example values

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

Depth (m)Absolute pressure (bar)152.52122.53.2749304.028837.54.7827455.5366607.0443

## Worked example

Inputs — Water type: Seawater; Depth: 30 m; Surface pressure: 101.325 kPa.

Results — Gauge pressure = 3.01554 bar; **Absolute pressure = 4.02879 bar**; Atmospheres absolute (ATA) = 3.9761 ATA.

## Key terms

- **Absolute pressure**: Gauge pressure plus atmospheric pressure.

## FAQ

**How much does pressure increase per 10 m of seawater?**
About 1 bar (1 atm).

**What is ATA?**
Atmospheres absolute – used by divers for gas calculations.

**Why does fresh water give less pressure?**
It is about 2.5% less dense.

**What is the pressure at the Titanic wreck (3,800 m)?**
About 385 bar.


## Sources

- [OpenStax – University Physics Volume 1](https://openstax.org/details/books/university-physics-volume-1)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)