# Marketing Attribution Split Calculator

> Split a conversion’s value across the channels in a customer journey using first-touch, last-touch, linear, position-based or time-decay rules.

Category: Marketing analytics · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/marketing-attribution-split-calculator

Rule-based attribution splits the credit for a conversion across the touchpoints that led to it. Enter the journey in order and pick a rule to see each channel’s share.

Also called: Attribution model calculator, Multi-touch attribution calculator.

## Inputs
- Journey, first touch to last (default Paid search
Email
Social
Email)
- Conversion value (default 1000)
- Attribution rule (options: Last touch, First touch, Linear (equal split), Position-based (40/20/40), Time decay; default position)
- Half-life (unit touchpoints; default 1)
- Currency

## Results
- Channel with the most credit
- Its credited value
- Its share of credit
- Touchpoints in the journey
- Distinct channels

## Formula

```
Last/first touch: 100% to the last/first touchpoint.  Linear: 1 ÷ n each.  Position-based: 40% first, 40% last, 20% shared by the middle (50/50 for two touches).  Time decay: weight 2^(−steps before last ÷ half-life), normalised to 100%.  Channel credit = Value × sum of its weights
```

Where:
- n: number of touchpoints in the journey
- Half-life: steps back from the last touch at which the weight halves

## Worked example
1. First touch (Paid search) gets 40% = $400; last touch (Email) gets 40% = $400.
2. The two middle touches (Email, Social) share 20%: $100 each.
3. Email total = 400 + 100 = $500 (50%); Paid search $400; Social $100.

**Result:** Under the 40/20/40 rule, Email earns $500 of the $1,000 conversion, Paid search $400 and Social $100.

## What the result means

Switch between rules to see how sensitive each channel’s credit is. A channel that looks strong only under last touch is mostly closing journeys others started; one that wins under first touch is mostly starting them.

## Assumptions and limits
- The journey list is complete and in the right order.
- Rule-based models assign credit by convention, not by measuring causal effect. Incrementality tests or data-driven models are needed for that.
- Time decay here uses steps between touchpoints, not elapsed days.

## Questions

### Which model is right?

None is objectively right. Pick one that matches the question you are asking, apply it consistently, and compare against a second rule to see how robust a decision is.

### Can I attribute many conversions at once?

Run one representative journey at a time, or apply the weights shown to the total value of conversions that share the same path.

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- [Cost Per Acquisition Calculator](https://calculators.geekmidst.com/calculators/cost-per-acquisition-calculator)
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Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/marketing-attribution-split-calculator