Your desk reference for email marketing math.
Stop searching for formulas. Bookmark this page and use these 15 essential calculations to measure what matters: revenue, profitability, and growth.
Print it. Pin it. Reference it daily.
Revenue & Profitability Formulas
1. Revenue Per Subscriber (RPS)
Formula: Total Email Revenue ÷ Total Subscribers
Example: £25,000 revenue ÷ 50,000 subscribers = £0.50 per subscriber
Benchmarks by Industry:
| Industry |
Monthly RPS |
Industry |
Monthly RPS |
| E-commerce |
£0.50-£2.00 |
B2B SaaS |
£1.00-£5.00 |
| Media |
£0.10-£0.50 |
Finance |
£2.00-£8.00 |
| Non-profit |
£0.05-£0.30 |
Healthcare |
£0.80-£3.00 |
Use it to: Forecast revenue, measure list quality, compare against benchmarks
2. Email List Value
Formula: Revenue Per Subscriber × Total Subscribers
Example: £0.50 RPS × 50,000 subscribers = £25,000 list value
Quick Calculation:
- Monthly value: Use monthly RPS
- Annual value: Multiply monthly RPS by 12, then by subscriber count
- Business valuation: Lists are typically valued at 2-3x annual revenue
Use it to: Justify growth investment, evaluate monetization, asset valuation
3. Campaign ROI
Formula: ((Revenue − Cost) ÷ Cost) × 100
Example: ((£8,000 - £2,000) ÷ £2,000) × 100 = 300% ROI
ROI by Campaign Type:
| Campaign |
Typical ROI |
Campaign |
Typical ROI |
| Promotional |
200-600% |
Abandoned Cart |
400-1,200% |
| Welcome Series |
500-2,000% |
Re-engagement |
150-400% |
| Product Launch |
300-800% |
Win-back |
100-300% |
Industry average: 3,600% ROI (£36 return per £1 spent)
Use it to: Prove email's value, prioritize campaign types, justify budget
4. Campaign Profitability
Formula: Revenue − Total Campaign Cost
Example: £12,000 revenue - £3,000 cost = £9,000 profit
Cost Checklist:
- Platform fees
- Creative production
- Labor/agency costs
- Tools & software
Quick Check:
- Positive profit → Scale it
- Negative profit → Fix targeting, offer, or creative
Use it to: Identify what to scale, what to fix, what to kill
5. Break-Even Revenue
Formula: Total Campaign Cost
Example: £200 platform + £500 creative + £400 labor = £1,100 break-even
Pre-Send Decision Framework:
Expected Revenue = Subscribers × Open Rate × Click Rate × Conversion Rate × AOV
If Expected Revenue > Break-Even → SEND
If Expected Revenue < Break-Even → OPTIMIZE FIRST
Use it to: Prevent unprofitable sends, set performance targets
6. Customer Lifetime Value (Email CLV)
Formula: Avg Purchase Value × Purchase Frequency × Customer Lifespan
Example: £60 × 4 purchases/year × 3 years = £720 CLV
Rule of Thumb: Email CLV should be at least 3x your subscriber acquisition cost
Example Economics:
- CLV: £720
- Acquisition cost: £2.00
- Ratio: 360:1 (Excellent)
Use it to: Set acquisition budgets, prioritize retention, segment high-value customers
Engagement & Performance Formulas
7. Email Open Rate
Formula: (Emails Opened ÷ Emails Delivered) × 100
Example: (2,200 ÷ 10,000) × 100 = 22% open rate
Benchmarks:
| Industry |
Avg Open Rate |
Industry |
Avg Open Rate |
| E-commerce |
15-18% |
B2B |
18-22% |
| Media |
20-25% |
Non-profit |
23-28% |
| Finance |
18-22% |
Retail |
16-20% |
Note: Less reliable since Apple iOS 15 privacy changes. Focus on clicks and conversions instead.
8. Click-Through Rate (CTR)
Formula: (Total Clicks ÷ Emails Delivered) × 100
Example: (350 ÷ 10,000) × 100 = 3.5% CTR
Benchmarks:
| E-commerce |
B2B |
Media |
Non-profit |
Finance |
| 2-3% |
2-5% |
4-6% |
2-4% |
2-3% |
Use it to: Measure content relevance, test CTAs, compare campaigns
9. Click-to-Open Rate (CTOR)
Formula: (Total Clicks ÷ Total Opens) × 100
Example: (350 ÷ 2,200) × 100 = 15.9% CTOR
Performance Scale:
- Below 10% → Content needs work
- 10-15% → Average
- 15-20% → Good
- Above 20% → Excellent
Why CTOR matters: Isolates content performance from subject line performance
10. Conversion Rate
Formula: (Conversions ÷ Emails Delivered) × 100
Example: (180 ÷ 10,000) × 100 = 1.8% conversion rate
Benchmarks by Campaign:
| Campaign |
Typical Range |
Campaign |
Typical Range |
| Promotional |
1-3% |
Abandoned Cart |
3-8% |
| Welcome Series |
3-10% |
Browse Abandon |
2-5% |
| Re-engagement |
0.5-2% |
Recommendations |
2-4% |
Impact: A 1% improvement on £100k revenue = £100k additional annual revenue
11. Bounce Rate
Formula: (Total Bounces ÷ Total Emails Sent) × 100
Example: (250 ÷ 10,500) × 100 = 2.4% bounce rate
Acceptable Ranges:
- Under 2% → Excellent list hygiene
- 2-5% → Acceptable
- 5-10% → Investigate sources
- Above 10% → Critical issue
Action: Remove hard bounces immediately. Remove soft bounces after 3-5 consecutive failures.
Growth & Efficiency Formulas
12. List Growth Rate
Formula: ((New Subscribers − Unsubscribes) ÷ Total Subscribers) × 100
Example: ((2,500 - 800) ÷ 45,000) × 100 = 3.8% monthly growth
Growth Benchmarks:
- 2-3% monthly → Healthy
- 1-2% monthly → Moderate
- Below 1% → Needs investment
- Negative → Fix retention or acquisition
13. Email List Churn Rate
Formula: (Unsubscribes ÷ Starting Subscribers) × 100
Example: (800 ÷ 45,000) × 100 = 1.8% monthly churn
Churn Benchmarks:
- Under 1% monthly → Excellent retention
- 1-2% monthly → Normal
- 2-3% monthly → Action needed
- Above 3% → Urgent fixes required
Annual churn: Most lists lose 25-30% annually (natural attrition)
14. Subscriber Acquisition Cost (SAC)
Formula: Total Acquisition Costs ÷ New Subscribers
Example: £5,500 total costs ÷ 2,750 new subs = £2.00 per subscriber
SAC by Channel:
| Channel |
Typical Cost |
Channel |
Typical Cost |
| Organic/SEO |
£0.50-£2.00 |
Social Ads |
£1.50-£5.00 |
| Content DLs |
£2.00-£8.00 |
Webinars |
£5.00-£15.00 |
| Co-marketing |
£1.00-£4.00 |
Paid Lists |
£5+/avoid |
Rule: Email CLV should be at least 3x SAC for healthy economics
15. Revenue Per Email Sent (RPES)
Formula: Total Revenue ÷ Total Emails Delivered
Example: £10,000 ÷ 50,000 emails = £0.20 per email
RPES Benchmarks:
| Campaign Type |
Typical RPES |
| Promotional blast |
£0.05-£0.20 |
| Segmented promo |
£0.15-£0.40 |
| Abandoned cart |
£0.30-£0.80 |
| Product launch |
£0.20-£0.60 |
| VIP segment |
£0.50-£2.00+ |
Use it to: Compare campaign efficiency regardless of list size, identify top performers
Quick Reference Table
| # |
Formula |
What It Measures |
Good Benchmark |
| 1 |
Revenue ÷ Subscribers |
List monetization |
£0.50-£2.00/month (ecomm) |
| 2 |
RPS × Subscribers |
Total list value |
Growing MoM |
| 3 |
(Rev - Cost) ÷ Cost × 100 |
Campaign ROI |
300%+ |
| 4 |
Revenue - Cost |
Campaign profit |
Positive & growing |
| 5 |
Total costs |
Break-even point |
Below expected revenue |
| 6 |
Value × Freq × Life |
Customer value |
3x acquisition cost |
| 7 |
Opens ÷ Delivered × 100 |
Subject line performance |
15-25% |
| 8 |
Clicks ÷ Delivered × 100 |
Content relevance |
2-5% |
| 9 |
Clicks ÷ Opens × 100 |
Content effectiveness |
15%+ |
| 10 |
Conversions ÷ Delivered × 100 |
Campaign effectiveness |
1-3% |
| 11 |
Bounces ÷ Sent × 100 |
List health |
Under 2% |
| 12 |
(New - Unsub) ÷ Total × 100 |
List growth |
2-3% monthly |
| 13 |
Unsubs ÷ Total × 100 |
List retention |
Under 2% monthly |
| 14 |
Costs ÷ New Subscribers |
Acquisition efficiency |
Depends on CLV |
| 15 |
Revenue ÷ Emails Sent |
Email efficiency |
Varies by type |
How to Use This Cheat Sheet
Before Every Campaign:
- Calculate break-even revenue (#5)
- Forecast expected revenue using historical RPES (#15)
- Decide: Send or optimize?
After Every Campaign:
- Calculate actual ROI (#3) and profit (#4)
- Update your RPES benchmarks (#15)
- Identify what worked (and what didn't)
Monthly:
- Track RPS (#1) and list value (#2)
- Monitor growth rate (#12) and churn (#13)
- Review acquisition costs (#14)
Quarterly:
- Calculate customer lifetime value (#6)
- Compare SAC to CLV economics
- Identify trends and opportunities
Save This Cheat Sheet
How to use it:
- Bookmark this page
- Print for your desk
- Add to reading list
- Share with your team
- Reference before every send
Pro tip: Link this page in your team wiki or Notion workspace for easy access.
Instead of building spreadsheets, many teams use Email Calculator to track these metrics automatically and save hours each week.
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