All three of the major search engine PPC advertising platforms provide “Campaign Budget Estimating Tools” to help figure out how much you need to spend in order to get your PPC Ads maximum exposure. Some are more reliable than others, but all of them are flawed.
The worst of the bunch has to be MSN’s. I’ve never seen it come even close to guessing a months Campaign spend. Three factors appear to me to be influencing it. It’s low search volume, its inconsistent adserving technology and not having the ability to set daily Campaign budgets – you can only set a monthly budget on MSN… I have some clients that actually get decent conversion numbers from MSN, so I need to use it. But I’ve given up on their ad serving and budget estimating. I’m now using the “Serve My Ads Until My Monthly Budget is Gone” setting. You can’t “Guestimate” my Costs over a month and serve out my impressions accordingly – it doesn’t work. They always serve my impressions short the first week, figure out they won’t spend enough, then over serve, then under serve, etc. Daily Campaign budgeting is much more uniform and reliable.
Yahoo Sponsored Search offers a Campaign budget estimating tool, but they also give you the option to not set a daily campaign budget. When you don’t set a daily Campaign budget Yahoo relies on the daily account budget. When you don’t set a Campaign budget and rely on just the Account daily budget you soon realize that there is no similarity in what you actually spend and what the Campaign budget estimator says you need for maximum visibility. I have a Campaign that spent $732 yesterday and the Campaign estimator said $301 should have covered it for the day.
Google AdWords has the most accurate Campaign Budget Estimator. It’s supposedly based on your current settings and the latest 2 weeks of click data. Its value is in showing if you are under-budgeting. It even tells you what percentage more impressions and how many more clicks you could get with more daily budget. The problem is if you budget over that ideal daily budget number it just says that your budget is “OK” and there is no need to change it at this time, which can often mean under-spending for the day.
With time, you will get a feel for how much you can and can’t spend on each Campaign and rely less on these tools. I’ve been trying to rely on them a lot in the last month because the addition of search query negatives some of my Campaigns got them so efficient, I suddenly found myself having a lot more money to spend on under-funded Campaigns.
Testing and using daily spending averages will go a long way toward finding out a good consistent budget amount.