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Ad budget calculator
Tell the calculator how many leads or sales you want each month and it works out the clicks, monthly budget and daily budget you need. For sales, it also shows the revenue and ROAS to expect.
Worked example.
A Halifax outdoor gear shop wants 90 online sales a month from Google Ads, with clicks costing around £0.75 and an average order of £55.
- Goal
- Sales
- Sales wanted per month
- 90
- Average cost per click
- £0.75
- Conversion rate
- 3%
- Average order value
- £55
The shop needs 3,000 clicks, a monthly budget of £2,250 (about £74 a day) and a cost per sale of £25.00. Those 90 sales would bring in £4,950, a ROAS of 2.20x, so the next step is to check that against the shop's break-even ROAS.
How it works.
The maths and the rules behind the tool, so you can check it yourself.
The calculator works backwards from your goal. If 3% of visitors become customers, you need roughly 33 clicks for each sale, so it divides the results you want by your conversion rate to find the clicks needed, rounding up to a whole click.
It then multiplies those clicks by your average cost per click to get a monthly budget. Dividing by 30.4 (roughly the number of days in an average month) gives a daily budget you can enter in Google Ads or Meta.
For sales goals, it multiplies your sales by your average order value to estimate revenue, then divides that by the budget to give your expected ROAS. Treat every figure as a starting estimate: real costs per click and conversion rates move as campaigns run.
Tips.
Small changes that make the numbers more useful.
- Use your own numbers where you can. Your conversion rate from GA4 or Shopify and your cost per click from past campaigns give a far better estimate than a guess.
- Starting from scratch? Keyword Planner in Google Ads shows estimated bid ranges for your keywords. Use the top of the range for a cautious budget.
- Run a test budget for two to four weeks before you commit to a bigger spend, then put your real cost per click and conversion rate back into the calculator.
- Small changes in conversion rate move the budget a lot. Going from 2% to 3% cuts the clicks you need by a third, so improving your landing page can be cheaper than raising your bids.
- Google Ads can spend up to twice your average daily budget on a busy day, but over a month you will not be charged more than your daily budget × 30.4. Expect some days to run higher than others.
Questions, answered.
How much should I spend on Google Ads?
Start from your goal, not a round number. Work out how many leads or sales you need, then use your cost per click and conversion rate to see what that costs. If the budget is more than you can afford, aim for fewer results first or work on your conversion rate.
How do I calculate a daily ad budget?
Divide your monthly budget by 30.4, which is roughly the number of days in an average month. A £1,500 monthly budget works out at about £49 a day. Google Ads uses the same 30.4 figure for its monthly charging limit.
What is a good conversion rate for ads?
It varies widely by industry, offer, price and traffic source, so there is no single good figure. A free quote form usually converts more visitors than a £200 purchase, because it asks less of people. Your own past results are the most useful benchmark, and the aim is to keep improving on them.
What is cost per acquisition (CPA)?
CPA is what you pay in ads for each lead or sale. You can work it out as cost per click ÷ (conversion rate ÷ 100), or as total ad spend ÷ number of results. If a click costs £1.50 and 5% of clicks convert, your CPA is £30.00.
Is there a minimum budget for Google Ads?
Google Ads has no minimum spend, so you can set any daily budget. The real limit is data: a budget that only buys a handful of clicks a day takes a long time to show what works. Use the calculator to check your budget can buy enough clicks for at least a few results each month.
More free tools.
Related calculators and generators. All free tools
Google, Bing, Meta, TikTok, Snapchat and LinkedIn ads.
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