Last Mile ROI Calculator

Your race.
Your numbers.

Adjust the sliders to match your race. The model updates live. Every assumption is visible — change any of them. The methodology behind these calculations is in the model addendum.

Quick-set by race tier
State House
$150K
Congressional
$1.5M
Senate
$8M
Custom
Your Race Inputs
Persuasion spend $1,500,000
Total dollars spent on voter persuasion (TV, mail, digital, canvassing).
$50K$20M
Cost per durable persuasion $570
Fully-loaded cost to durably shift one voter. Door-knock: ~$570 (Gerber-Green). Digital-heavy: $300–400.
$200$1,000

Post-contact search rate 22%
Share of persuaded voters who go online to search or verify after contact. Higher for younger, high-engagement electorates.
5%50%
AI encounter rate 60%
Share of those searches that encounter AI-generated content (Google AI Overview + dedicated tools). Rarely below 50% in federal races.
20%90%
Unfavorable answer rate 20%
Share of AI responses containing errors, gaps, or unfavorable framing. This is the number you don't know without a diagnostic. The model's key unknown.
0%75%
Reversal rate 35%
Share of voters who encounter an unfavorable AI answer and have their persuasion materially reversed.
5%70%
Recovery cost multiplier
How many times the original persuasion cost it takes to recover a reversed voter. Derived from the Nature/Science AI persuasion research (4× ceiling).
Program Costs to Evaluate
Diagnostic cost $5,500
One-time. Enter the actual or expected price of your diagnostic.
$500$25,000
Remediation cost $11,500
One-time. Conditional on diagnostic findings.
$500$75,000
Monthly monitoring $2,000
Per month. Number of months is set by your race length.
$250$10,000
Active race months 6
1 mo18 mo
Persuasion value at risk
$42,000
2.8% of persuasion spend
Chain of Loss
Persuasions purchased 2,632
Post-contact AI encounters 348
Unfavorable encounters 70
Estimated reversals 24
Recovery cost per reversal $1,710
Program Costs vs. Value at Risk
Diagnostic 13% of VAR
Remediation 27% of VAR
Monitoring (full period) 29% of VAR
Full program total $29,000
Full program as % of persuasion spend 1.9%
Break-Even: Reversals to Justify Each Program
Diagnostic
$5,500
4
reversals to break even
16% of modeled reversals
Remediation
$11,500
7
reversals to break even
29% of modeled reversals
Monitoring
$12,000
8
reversals to break even
33% of modeled reversals
Break-even = program cost ÷ (cost per persuasion × recovery multiplier). A value below 100% of modeled reversals means the program breaks even before exhausting estimated exposure.
About This Model

This calculator implements the chain-of-loss model from The Last Mile Problem. All inputs are visible and adjustable. The unfavorable answer rate is the key unknown — it is the number a diagnostic produces for your specific candidate. Without it, the model produces a range; with it, the value at risk becomes a specific dollar figure for your race. Full methodology, input rationale, and sensitivity analysis: model addendum.

The author has a commercial interest in this subject. That interest is disclosed so you can evaluate the analysis in context. The model is structured to be stress-tested — adjust the inputs until it breaks, and see what happens.