About the Marketing Attribution Calculator
This marketing attribution calculator shows how much credit each channel gets for a conversion under the five classic rules-based attribution models. List the touchpoints in the customer journey in order — for example Paid Search, Facebook Ads, Email, Direct — with how many days before the conversion each happened, enter the conversion value, and pick a model. It returns the channel that earns the most credit and a side-by-side table comparing first-touch, last-touch, linear, time-decay and position-based (U-shaped) attribution.
It is built for marketers explaining why channel reports disagree, analysts choosing a model for a dashboard, and agencies showing clients how upper-funnel channels are undervalued by last-click reporting. Seeing the same journey scored five ways makes the trade-offs obvious.
Repeated channels are added together. If you leave out the days, touches are assumed to be one day apart. Time decay uses a half-life you can change (7 days by default), and position-based gives 40% each to the first and last touch by default. These are rules-based models; data-driven attribution in tools like GA4 instead learns weights from many converting and non-converting paths.
How to use the marketing attribution calculator
- 1List each touchpoint on its own line, first interaction at the top.
- 2Add the number of days before the conversion after a comma (optional).
- 3Enter the conversion value to see credit in money as well as percent.
- 4Choose a model, adjusting the half-life or first/last share if needed.
- 5Compare the five models in the table to see how much each channel’s credit swings.
Formula and method
First-touch gives 100% of the credit to the first interaction and last-touch gives 100% to the final one. Linear splits credit equally across all k touchpoints. Time decay weights each touch by 2 raised to minus its days-before-conversion divided by the half-life, so a touch one half-life earlier gets half the weight, then normalises the weights to sum to 100%.
Position-based (U-shaped) gives a share p to the first and last touches (40% each by default) and spreads the remaining 1 − 2p equally over the middle touches; with two touches each gets 50%. Credit for a channel that appears more than once is summed, and attributed value is the credit share multiplied by the conversion value.
- k
- Number of touchpoints in the path
- daysᵢ
- Days between touch i and the conversion
- half-life
- Days for a touch’s weight to halve (time decay)
- p
- Share given to the first and the last touch (position-based)
Worked examples
Four-touch journey with time decay (7-day half-life)
Weights are 2^(−21/7) = 0.125, 2^(−10/7) = 0.372, 2^(−3/7) = 0.743 and 1 for the same-day Direct visit, summing to 2.240. Direct gets 1 ÷ 2.240 = 44.65%, or $446.53 of the $1,000 conversion.
Linear model with a repeated channel
Each of the four touches gets 25%. Organic Search appears twice, so it collects 50% — $250 of the $500 conversion — while Email and Paid Social get $125 each.
Position-based (40/20/40) on a five-touch path
Display (first) and Direct (last) get 40% each — $800 apiece — and the three middle touches share the remaining 20%, about 6.67% or $133.33 each. On a tie the earlier channel is listed as the top channel.
First-touch credit
First-touch attribution gives the whole $1,000 to Paid Search, the channel that started the journey — the opposite of last-touch, which would credit Direct.
Frequently asked questions
What is the difference between first-touch and last-touch attribution?+
First-touch gives all the credit to the channel that introduced the customer, favouring awareness channels. Last-touch gives it all to the final interaction before converting, favouring direct, branded search and email. Both ignore every other touch.
How does time-decay attribution work?+
Touches closer to the conversion get more credit. With a 7-day half-life, a touch 7 days before conversion gets half the weight of a same-day touch and a touch 14 days before gets a quarter; the weights are then scaled to total 100%.
What is position-based (U-shaped) attribution?+
It gives a fixed share — commonly 40% each — to the first and last touches, recognising both the channel that created demand and the one that closed it, and spreads the remaining 20% evenly across the touches in between.
Which attribution model is best?+
No rules-based model is correct for every business. Linear and position-based are reasonable defaults for multi-step journeys; last-touch suits short, impulse purchases. Comparing models side by side shows which channels are sensitive to the choice, and incrementality tests are the best way to validate them.
What attribution model does GA4 use?+
Google Analytics 4 uses data-driven attribution by default for key events, with paid and organic last-click as an alternative. Google removed the first-click, linear, time-decay and position-based models from GA4 in 2023, which is why many marketers calculate them separately.