Google Ads budget calculator: plan spend from revenue, CPC, and ROAS

Divide the revenue target by the ROAS your margins require. A $12,000 monthly revenue goal at a 3x target ROAS gives a $4,000 budget. That single division is the budget; the rest of the plan checks whether the budget can work.

Three more numbers make the check. Orders needed = $12,000 / $80 average order value = 150 orders. Clicks needed = 150 / 2.5% conversion rate = 6,000 clicks. Max CPC = $4,000 / 6,000 clicks = $0.67. If clicks in your niche cost more than $0.67, this exact plan cannot hit both the revenue goal and the ROAS target.

Run the math before spending a dollar. The most useful output is usually the max CPC, because it is the first number that collides with reality.

Four inputs: average order value, conversion rate, expected CPC, and contribution margin. Use your own trailing data wherever it exists. Where it does not, start from planning ranges and replace them with real numbers within the first two weeks of spend.

The ranges below are rules of thumb for 2026 planning, not verified benchmarks. CPCs and conversion rates vary widely by niche, country, keyword intent, and landing page, so treat every row as a starting guess with a stated replacement plan.

Compare expected ROAS with break-even ROAS. Expected ROAS is target revenue divided by the budget. Break-even ROAS is 1 divided by contribution margin: a 40% margin needs 2.5x, a 45% margin needs 2.22x, and a 30% margin needs 3.33x before the ads stop losing money.

A plan that buys the revenue can still lose. Spending $7,200 to make $12,000 is a 1.67x ROAS, which loses money at any margin below 60%. When expected ROAS lands under break-even, more spend makes the loss bigger, so fix the economics first.

Change an input, not the honesty of the math. The $12,000 plan above allows $0.67 per click; if Keyword Planner shows $1.20, the gap closes only through a higher conversion rate, a higher order value, a lower ROAS target, or cheaper traffic.

Each lever has a size. Raising conversion rate from 2.5% to 4.5% cuts clicks needed from 6,000 to 3,334, which lifts max CPC from $0.67 to $1.20 on the same $4,000 budget. Raising AOV from $80 to $144 does the same through fewer orders. Dropping the ROAS target below break-even is the one move that never works, because it plans a loss on purpose.

Divide the monthly budget by 30.4, the average number of days in a month and the multiplier Google uses for monthly spend limits. A $4,000 monthly budget is $131.58 per day; a $750 monthly budget is $24.67 per day.

Google can spend up to twice the daily budget on a strong day, but the month is capped at 30.4 times the daily setting, so the monthly plan holds even when individual days spike. Review performance in weekly blocks rather than daily ones, and pre-set a maximum test budget so learning never becomes accidental overspend.

Recompute the plan's four numbers from real data: CPC = cost / clicks, CPA = cost / conversions, conversion rate = conversions / clicks, and ROAS = revenue / cost. Then subtract non-ad costs so a healthy-looking ROAS cannot hide a loss after COGS, fulfillment, and fees.

A campaign that spent $1,500 for 2,000 clicks, 60 conversions, and $4,800 revenue ran at a $0.75 CPC, $25 CPA, 3.0% conversion rate, and 3.2x ROAS. With $2,400 in non-ad costs, profit after ads is $4,800 - $1,500 - $2,400 = $900. Compare each real number against the plan and move budget toward whichever input beat its forecast.