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What is Bandwidth & Data Transfer in Web Hosting? How Much Do I need?

When researching and choosing a web host to host your domain, one factor to evaluate and compare is the cost of your required amount of bandwidth,

Yes, many providers offer “unlimited” hosting plans, but upon taking a closer look, you’ll find that unlimited isn’t truly unlimited – there are always penalties if you use too much as is based on a “normal” usage, whatever that means. That said, knowing how much bandwidth your site truly requires can be a bit of an art form.

Understanding the Terms “Bandwidth” & “Data Transfer” in Web Hosting

Essentially, bandwidth is a term to calculate the rate of traffic and data allowed to flow between users and your site via the internet. The term “bandwidth” is often misused to describe “data transfer” but in reality, these two are two different things.

What is Data Transfer?

Data transfer refers to the actual amount of data that is moved from one place to another. Typically, data transfer is measured over a month for web hosting purposes. This involves the total of all the data that your website sends to its visitors, including web pages, images, files, etc.

What is Bandwidth?

Bandwidth is the measure of maximum data that can be transferred in a given time, usually measured in seconds. Bandwidth is a measure of web hosting capacity and speed.

Data Transfer vs Bandwidth

The number in “data transfer” tells you how much data you can transfer in a month. The number in “bandwidth” tells you how fast the data can be transferred.

Imagine bandwidth as the width of a water pipe where data transfer is the amount of water flowing out from the pipe. How wide is the pipe width (bandwidth) determines how fast can water (data) flows.

In the context of web hosting services, when we talk about “bandwidth,” we're often referring to the allocated data transfer. But the two terms are used interchangeably so often in this context that “bandwidth” has essentially taken on the same meaning as data transfer to many people.

This can definitely cause some confusion, but rest assured that when most web hosting companies talk about “bandwidth,” they're referring to the total amount of data your website can serve to visitors over a month.

How Much Bandwidth Do You Need?

Formula used to calculate needed website bandwidth is not that complicated!
The formula used to calculate needed website bandwidth is not that complicated!

Think about bandwidth like a pair of pants: you need the size that you need. It doesn’t make a whole lot of sense to buy up a size, but at the same point, there’s a number that fits. If your waist is a size 36, you simply aren’t going to fit into that 32. Simple math.

3 Steps to Calculate the Bandwidth Your Website Need

Here’s how to calculate the required bandwidth for your website:

  1. Estimate the average page size of your site in kilobytes (MB).*
  2. Multiply that average page size (in KB) by the monthly average number of visitors.
  3. Multiply the result from Step 2 by the average number of page views per visitor.

If you don’t know, use Pingdom’s Load Time test on a few pages and take the average of those tested pages for your base testing number. Here are some real-life examples:

Example #1: The size of YouTube.com homepage = 2.0 MB.
Example #1: The size of the YouTube.com homepage = 2.0 MB.
Example #2: The size of WHSR homepage = 1.1 MB.
Example #2: The size of the WHSR homepage = 1.1 MB.

This is the base of knowing your required bandwidth – however, you’re not done quite yet. You also need to include an allocation for extra “room” in case your traffic spikes. Generally speaking, I recommend giving at least a 50 percent spread. But you need to allocate extra room to grow and traffic spikes – leave at least 50% tolerance.

Scenario #1: Needed Bandwidth for Website Without User Downloads

To do this calculation, use the following formula:

Bandwidth needed = Average Page Views x Average Page Size x Average Daily Visitors x Number of days in a month (30) x Redundant Factor

  • Average Daily Visitors: The total number of monthly visitors/30.
  • Average Page Size: The average size of your web page.
  • Average Page Views: The average page viewed per visitors.
  • Redundant Factor: A safety factor ranged from 1.3 – 1.8.

Scenario #2: Needed Bandwidth for Website With User Downloads

If your site does not use or allow downloads:

Bandwidth needed = [(Average Page Views x Average Page Size x Average Daily Visitors) + (Average Download per day x Average File Size) ] x Number of days in a month (30) x Redundant Factor

  • Average Daily Visitors: The total number of monthly visitors/ 30.
  • Average Page Size: The average size of your web page
  • Average Page Views: The average page viewed per visitor
  • Average File Size: The total file size divided to the number of files
  • Redundant Factor: A safety factor ranged from 1.3 – 1.8.

How Bandwidth Capacity Affects Your Web Hosting Choices

Bandwidth plays a crucial role in the performance and scalability of a website. If your site has a high amount of interactive content or multimedia, a web hosting plan with more bandwidth ensures faster loading times – thus enhancing user experience. Additionally, as website traffic grows, more data is transferred, necessitating more bandwidth.

A hosting plan with low bandwidth may result in slow site speeds or even crashes during high-traffic periods.

From a financial perspective, hosting plans (cloud hosting especially) with higher or unlimited bandwidth generally cost more, hence it's vital to balance bandwidth needs with your budget. Some hosting providers also charge additional fees for exceeding your bandwidth limit. Therefore, understanding your website's bandwidth needs not only improves site performance and scalability but also ensures cost-effective operations.

Insubstantial Factor If You Are New

If you're just starting out with a simple website (like a personal blog or a small portfolio site) and don't expect a lot of traffic, bandwidth might not be your primary concern when choosing a web host.

First, because your website is new, you are very unlikely to consume significant bandwidth. This is especially true if your site is primarily text-based and doesn't have high-resolution images, videos, or interactive features.

Secondly, most shared hosting plans come with generous bandwidth offers today. 90% of the new users are getting more capacity in data transfer than they can consume from the hosting provider.

There are simply other more important factors to look into when choosing a web host. To learn more, read our best web hosting guide.

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Article by Jerry Low

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