Introduction
The first week of your campaign is the most effective. By week six, you are spending the same amount but reaching fewer new people and earning less per dollar spent. This is audience fatigue and diminishing returns. The audiences most likely to respond are reached first. As the campaign continues, you pay to reach less interested audiences with increasingly familiar creative. A paid social campaign might generate 150% ROI in week one but negative ROI by week four. Understanding when your campaign crosses from profitable to unprofitable determines how long to run it. This tool models the decay curve for seven channels so you can see exactly when each stops generating positive returns.
What This Tool Calculates
The tool uses an exponential decay function calibrated to each channel's half-life. Paid social has a half-life of approximately 3 weeks. Google/YouTube ads: 4 weeks. PR/press: 2 weeks. Influencer: 2.5 weeks. Email: 1.5 weeks. Festival buzz/word of mouth: 6 weeks. Theatrical/OOH: 1 week. An audience fatigue factor reduces effectiveness by 3% per week regardless of channel. For each week, the tool calculates impressions, conversions, revenue, and weekly ROI. The chart shows spend versus revenue across the campaign.
The Formula and How It Works
Paid social starts strong but decays quickly (3-week half-life) because audiences see the same ads repeatedly. Creative rotation can extend but not eliminate decay. Google/YouTube ads decay slower (4-week half-life) because search ads reach users with active intent. PR has a sharp 2-week half-life because news cycles move fast. Festival buzz has the longest half-life (6 weeks) because word of mouth propagates through social networks over time. Email decays fastest per-send (1.5 weeks) due to list fatigue, but has the highest initial conversion rate.
Real-World Examples
Finding the Optimal Cutoff Point
The optimal cutoff is the last week where weekly ROI is positive. Beyond this, every dollar spent generates less than a dollar in return. The tool identifies this automatically. Money spent after cutoff generates better returns if reallocated to a fresh channel or saved for a future release window. The tool shows both weekly and cumulative ROI so you can make this decision with data.
Budget Allocation Across Campaign Phases
| Detail | Value |
|---|---|
| Effective campaigns concentrate spending in three phases. | |
| Phase 1 (awareness, 4 to 6 weeks before release): PR, influencer, paid social. | |
| Phase 2 (conversion, first 2 weeks of release): Google ads, email, retargeting. | |
| Phase 3 (sustain, 2 to 4 weeks after): word of mouth, community, algorithmic discovery. | |
| Rather than fighting decay by increasing spend, transition to the next phase and channel mix. |
Pro Tips and Common Mistakes
Pro Tips
- Revenue per conversion determines when weekly ROI turns negative.
- TVOD conversion: $2.50 to $3.25 after fees.
- AVOD conversion: $0.01 to $0.05.
- Theatrical ticket: $4 to $6 after exhibitor share.
Common Mistakes
- Run the simulator for each planned channel.
- $2,000/week on paid social for 8 weeks might generate $6,000 total with cutoff at week 5.
- Same budget on influencer: $4,500 with cutoff at week 4.
Frequently Asked Questions
What is a marketing half-life?
The number of weeks for a channel's conversion effectiveness to drop 50% from initial level. A 3-week half-life means 50% effective in week 3, 25% in week 6, 12.5% in week 9. Different channels have different half-lives based on audience behavior and platform dynamics.
How much should I budget for film marketing?
30% to 50% of production budget for theatrical releases. 10% to 25% for streaming-first releases. A $500,000 indie film should budget $50,000 to $125,000 for marketing depending on distribution strategy.
Can I extend effectiveness?
Creative rotation (new visuals every 5 to 7 days) can extend half-life by 20% to 40%. Audience expansion can reset decay temporarily. These tactics slow decay but cannot eliminate it. Every channel eventually reaches negative weekly ROI for a given title.
Start Calculating
Decay curves model average patterns. Individual campaigns can outperform or underperform based on creative quality, targeting, competition, and external events (a viral moment, celebrity mention). The model assumes constant spend and does not account for creative rotation or audience expansion that can temporarily reverse decay. Use the curve as a planning baseline and measure actual performance against it. If week 6 exceeds the model, your creative is resonating and you should continue. If week 2 is below model, pivot sooner.
