---
title: "Pressure Sand and Carbon Filter Sizing Calculator | Filtsap"
description: "Size a pressure sand filter (PSF), multimedia filter (MMF) or activated carbon filter (ACF): enter flow to get filter area, FRP vessel size, media volume and backwash flow."
source: https://www.filtsap.com/tools/pressure-filter-sizing-calculator/
updated: 2026-10-23
---

Free calculator

# Pressure sand and carbon filter sizing calculator

Enter your flow rate and filter type. The calculator gives the filter area you need, the FRP vessel size, the media volume and the backwash flow your pump has to supply.

## Result

Results appear here as you type.

## How the calculator works

- **Filtration velocity:**  10 m/h for sand and carbon filters, 12 m/h for multimedia filters, which are typical design values.
- **Area per filter**  = flow per filter ÷ velocity. The calculator picks the smallest standard FRP vessel with at least that area.
- **Carbon filters**  also need contact time: at least 5 minutes of empty-bed contact for chlorine removal. If the area-based vessel is too small for that carbon volume, the calculator moves up a size.
- **Media volume**  is about 60% of the vessel volume (media plus support gravel), leaving freeboard for backwash.
- **Backwash flow**  = vessel area × 30 m/h for sand and multimedia, 20 m/h for carbon. Your feed pump or a separate backwash pump must deliver it.

Related: [FRP vessel size chart](https://www.filtsap.com/guides/frp-vessel-size-chart/) , [MMF, ACF and PSF systems](https://www.filtsap.com/build/water-treatment-systems/) , [multiport valve positions](https://www.filtsap.com/guides/multiport-valve-positions/) .

## FAQs

What is the filtration rate of a pressure sand filter?

Typically 8 to 12 m³ per m² per hour (m/h). 10 m/h is a common design value.

How do I size an activated carbon filter?

Check both area (about 10 m/h) and contact time (at least 5 minutes empty-bed contact for chlorine, longer for organics). Use whichever needs the larger vessel.

What backwash flow does a sand filter need?

About 25 to 30 m/h across the filter area. For a 24-inch vessel that is roughly 8 to 9 m³/hr.

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## Need an exact design?

Send your water analysis and flow. An engineer checks it and replies on WhatsApp.

[Request a quote](https://www.filtsap.com/get-quote/)

## Need filters, spares or a new plant?

Send the details on WhatsApp or through the form. An engineer reads every enquiry before we quote.

[Get a quote](https://www.filtsap.com/get-quote/) [WhatsApp](https://wa.me/918160852169?text=Hello%20Filtsap%2C%20I%20need%20a%20quote.)