Methodology overview

Calculation Assumptions

The exact conversion rates and revenue model used by the WhatsApp Impact Calculator. These commitments match the calculator on hellomerx.com.

Conversion Rate Assumptions

Channel	Conversion rate	Notes
Online Sessions	0.5% monthly (6% annually)	Applied monthly, equivalent to 6% across 12 months
SMS Subscribers	6%	One-time conversion
Email Subscribers	0.3%	One-time conversion
Social Followers (Instagram, etc.)	0.4%	One-time conversion
Store Walkthroughs (QR Code Scans)	0.5%	QR code scan conversions

Campaign Frequency & Diminishing Returns

Revenue per campaign falls as send frequency rises, because extra sends compete for the same customer attention. From 3 campaigns a month onward, monthly revenue per subscriber is capped at £3.60 — sending more earns nothing extra.

Campaigns / month	Revenue / campaign	Revenue / subscriber / month	Marginal gain
1default	£2.00	£2.00	+£2.00
2	£1.50	£3.00	+£1.00
3	£1.20	£3.60	+£0.60
4	£0.90	£3.60	None

Revenue Model

Default campaigns per subscriber per month: 1 (change it under Advanced assumptions in the calculator)
Revenue per marketing campaign at the default: £2.00
Monthly revenue per subscriber: £2.00
Annual revenue per subscriber: £24
Welcome journey conversion (one-off, new subscribers only): 20.00% at the default £50 average order value
Default average order value: £50 — implying 4.00% conversion per campaign and 20.00% on the welcome journey. Order value never changes the forecast — it only restates the same revenue as a conversion rate.
Existing WhatsApp subscribers are active for the full 12 months.
New subscribers are acquired evenly throughout 12 months.
Each new cohort earns revenue only for its remaining months in year one.
The welcome journey pays out once, in the month a new subscriber joins.
Average time active in year one: 6.5 months

Monthly Ramp Calculation

January subscribers are active for 12 months, February subscribers for 11, and so on until December subscribers are active for one month.

(12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1) ÷ 12
= 6.5 months

Revenue Formula

Year 1 Revenue = (Existing Subscribers × £24) + (New Subscribers × £23.00)

Existing subscribers earn campaign revenue only: £2.00 × 1 campaign per month × 12 months = £24. Each new subscriber enters the one-off welcome journey, modelled at 20.00% conversion on the default £50 average order value, plus £13.00 of campaign revenue across an average 6.5 active months, for £23.00 in year one.

Existing base + year-one acquisition revenue

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