Published on by Digitally Squared

If you are looking to improve your Adwords conversion rate while reducing your cost per conversion, implementing Adwords mobile bid adjustments is a quick and convenient tactic that will allow you to do this. If your website is not as well optimised for mobile devices as it is for desktop devices then your conversion rate is likely to be lower on mobile devices. A research by IBM from a range of retailers showed that on average desktop devices convert the best and mobile devices convert the worst, with tablet in the middle.


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This presents you with a good opportunity to optimise how you are spending your Adwords budget. You will want to spend as much of your budget as possible on the devices that is converting the best and the least amount of your budget on the devices that is converting the worst

By doing this you will generate the maximum number of conversions for your budget, whether they are sales on your website, phone enquires or users filling out a contact form on your website.

What Are Adwords Mobile Bid Adjustments?

What are Adwords mobile bid modifiers? They allow you to tell Google how much you want to increase or decrease your bids by on each device.

Let’s say for example that your adverts convert twice as well on mobile devices than they do on desktop devices then you may want to double your bids on mobile devices so that they get twice as much of your budget. To double the bids you would need to use an Adwords bid adjustment of 100%. So say for example that your current bid on keywords is £3 then this would increase this bid to £6 on mobile devices which would mean that it will appear higher in the search results and generate more traffic and conversions.

Where Can I Find Mobile Bid Adjustments?

Adwords Mobile bid adjustments as updated by Google this May 2016 can be set in both the standard Adwords interface or using Adwords editor for more advanced users. Within the standard Adwords interface mobile bid adjustments can be found within the campaign settings of your account.


To set a mobile bid adjustment you should select the two dashed line that can be seen within the bid adjustment column. Once you have done this you have two options. You can either increase bids by a certain percentage, or decrease bids by a certain percentage.


The percentage must be a whole number between -100% to +900%. If no bid adjustment is entered the bid on mobile devices will be the same as desktop.

When you set bid adjustments in several different dimensions they are multiplied together not summed. So for example if you had a starting bid of £1 and then you increased your bids by 20% on Mondays your bid would then be increased to £1.20. If you then increase your bids on mobile devices by 30% then you would increase £1.20 by 30% which would give you a bid of £1.56.

To make this easier for you to calculate so that you don’t have to do the maths every time Google have created a bid calculator that you can use to show how your bid would be effected by using different bid modifiers.


How to calculate Adwords Mobile Bid Adjustments

You should calculate your bid modifiers using the following formula.


So for example if your conversion rate for mobile devices is 5.68% and the average conversion rate for the campaign (for all 3 devices) is 3.49% you will see that mobile devices are converting well and more budget should be allocated towards them. In this case by plugging the numbers into this formula you will end up with a mobile bid adjustment of 63%.

I want to Generate more phone leads

You could also use this method to optimise bids to generate the maximum number of offline conversions which would be useful for most service based companies.


If that mobile devices had generate 100 out of the 180 total phone calls then I would make the calculation (100/60)-1*100. Here the 60 the number of phone calls expected based on the 180 total if each devices were equally responsible for each phone lead.

I want more revenue per click

This is the option that Google suggest that you use and is more stable than ROAS (Return On Ad Spend) bidding. This option like ROAS bidding will not be suitable for advertisers that don’t have accurate conversion values in place. Here is the calculation that you would need to use.screen-shot-2016-11-12-at-21-31-53For example if you have a retailer that has sold £15K on desktop devices this month from 10K clicks the value per click or revenue per click would be £1.50. Similar if the advertisers had sold £12K on mobile devices from 10K clicks the value pre click would be £1.20. If we plug these numbers into this calculation then we would get a mobile bid adjustment of -20%.

Adwords Scripts that calculate Adwords mobile bid adjustments

For more advanced users there are several Adwords Scripts that allow you to calculate your Adwords mobile bid adjustments automatically. Adwords Scripts for those of you who are unfamiliar are pieces of javascript code that can be passed into your Adwords account to automate certain tasks.

The AdWords Script can set the mobile bid multiplier at the campaign level, but if you want to get more granular and apply bid modifiers to ad groups, you have to take the outputs as a spreadsheet for use with AdWords Editor because ad group level modifiers are not yet supported in Scripts.

For full documentation on how to setup and customise the script for advanced users can be found here. For users who are just starting out with Adwords Scripts here is a short guide that will explain how to copy and paste the script into Adwords and get it up and running.


Overall Adwords mobile bid modifiers present a great opportunity for advertisers to improve the performance of their Adwords accounts by distributing more budget to the best performing devices.

When it comes to calculating your mobile bid adjustments you first need to ensure that you have enough data to make a statistically significant decision. Then secondly you need to make sure that you have choose the right calculation to make based on your goals, whether it be to generate more conversions, maximise ROAS or generate more phone calls.

For more advanced advertisers, they can manage accounts with automating this task is essential and this is where Adwords Scripts can come in useful for automatically calculating your mobile bid modifiers and setting them. Try out Skyline, we are the experts in leveraging the power of PPC through Google AdWords.

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