Ad budget calculator

Work backward from a conversion goal and an assumed cost per acquisition to a budget you can compare against your resources.

Free to use. No account required.

Enter your numbers

The prefilled numbers are an example. Replace them with your own inputs.

Currency

Labels monetary inputs and results; no exchange-rate conversion.

Conversion goal

One defined outcome, such as 100 qualified leads.

Assumed cost per conversion

Use your own comparable campaign data where available.

Campaign length (days)

The calculator divides total budget evenly across these days.

Your results

Planned total budget: $2,500.00; Conversion goal × assumed CPA
Average daily budget: $83.33; Planned total ÷ campaign days
20% lower CPA scenario: $2,000.00; Conversion goal × assumed CPA × 0.8
20% higher CPA scenario: $3,000.00; Conversion goal × assumed CPA × 1.2

How to use the result.

By IG Ad Library · Updated October 23, 2026. Calculations run in your browser.

Turn a goal into a spending scenario

Total planned spend = conversion goal × assumed CPA. Average daily spend = total planned spend ÷ campaign days. This is planning arithmetic; it does not predict what an ad platform will deliver or bill each day.

Give the assumption room to move

The lower and higher cost scenarios use CPA values 20% below and above your input. They are sensitivity checks, not confidence intervals or industry benchmarks. Replace them with your own observed range when available.

Choose a measurable test before scaling

Define the conversion event and decide how you will compare creatives before assigning the budget. Avoid splitting a small budget across so many variants that each receives too little data to support a decision.

Worked example

A goal of 100 conversions at an assumed CPA of 25 requires a planned total of 2,500. Across 30 days, that is an average of 83.33 per day. CPA scenarios of 20 and 30 imply totals of 2,000 and 3,000.

Common questions.

Will this budget guarantee the conversion goal?

No. Auction prices, conversion rates, creative quality, audience size and measurement all affect delivery. The result expresses the assumption you entered, not a forecast or guarantee.

Should every ad receive an equal budget?

Equal allocation can help a controlled comparison, but it is not always how platform optimization delivers spend. Choose an experiment design and inspect actual exposure before interpreting the outcome.

Apply it to a creative reference.

Study the opening, promise and evidence in a real ad before deciding what to change.