Google Ads forecast calculator. Spend and conversions to month end, weekday by weekday.

A plain run rate divides what you did so far by the days gone and multiplies by the days in the month. It treats every day alike. A B2B account can take a third of its weekday leads on a Saturday, so a month with six weekend days left ends lower than one with two. This calculator weighs each day by its weekday.

The method

1. Each weekday gets a weight, 100% being an average day. "Learn from my days" reads the weights from your daily figures: each weekday's average, with the average of all days counted as one more day of it. One odd Tuesday cannot swing the result. "Set it myself" takes yours. "None" counts every day alike.
2. The days counted add up to a number of weighted days. Nine weekdays and two weekend days at 30% make 9.6.
3. The rate is what you did so far divided by those weighted days.
4. The days left are weighed the same way. The forecast is what you did so far, plus the rate times the weighted days left.

The likely range

With at least 10 days pasted day by day, the calculator takes every run of seven days so far and compares it with what the rate expected of it. Each seven-day run holds every weekday once, so this measures how much your weeks swing. The range applies the middle 60% of those misses (the 20th to the 80th percentile) to the days left.

For conversions, the range is never narrower than chance alone allows. A week with 50 leads could as easily have brought 43 or 57, and a rate read from a few dozen is itself unsure. The calculator adds that spread. With totals only, it is the one range it can show, and the narrowest honest one: real months move more.

A worked example

Ledgerline, a made-up accounting firm, runs lead ads on weekdays and keeps a small budget at weekends, when leads fall to about 30% of a weekday. On the morning of 12 September 2026 it has 88 leads from the first 11 days, Tuesday 1 to Friday 11: nine weekdays and two weekend days.

Six of the 19 days left fall on a weekend, against two of the first 11. The plain run rate misses that and promises 16 leads the firm will not get. With totals only, the likely range is 208 to 239 leads.

Forecast or budget pacing?

The budget pacing calculator answers another question: is spend on track against a budget you set, and what daily budget lands the month on it? This one needs no budget. It projects spend and conversions from how the account has behaved, so you see a short month coming before the client asks. To turn a monthly goal into a daily pace, use the conversion goal calculator.

What Optizads does on a connected account

This calculator is a simplified, transparent version of the Optizads forecast. In the app, the forecast learns from your account's own history every night, follows your budgets and the conversions still to come, and shows the month end with a likely range on the Overview and on Goals. How the Optizads forecast works explains it in plain words.

Paused campaigns count for nothing, the conversions Google is still adding to recent days are counted, and spend never goes past what the budgets let Google charge. The forecast and its range sit on the Goals page and on the Overview's This month card.