Your budget requirement is determined by your estimated Cost Per Click and click volume estimates as well as the competitiveness of the industry.
Let’s start with the Cost Per Click factor.
We have a rule about the lower threshold when it comes to the amount of daily clicks a campaign should capture. We believe you should get at least 10 clicks daily in order for your website to receive sufficient traffic from your AdWords effort.
We’d prefer to capture a lot more traffic, but if we needed to establish a baseline then it’s 10 clicks for local service campaigns.
If the average Cost Per Click in your industry is $4, then we need at least a $40 budget to be able to reach this level. This doesn’t mean that we’re OK with a $3 budget if the CPC is 30 cents. We still have a minimum daily budget of $30 for AdWords campaigns.
The Industry and Service/Product Have Different Conversion Data
Each industry has its own conversion standard and minimum budget required to be competitive in a certain industry might be higher than in another.
For instance, the Cost Per Click in the insurance industry is a lot higher than the cosmetics industry. There are more advertisers promoting insurance, thus competition is greater for related keywords.