Technical documentation · Rules 2026-10-22.1
How this cost is calculated
Volunteers deliver the sessions. Software handles the coordination.
- Verified hours
- 439.2
- Completed sessions
- 670
A verified impact hour is real time spent together by a volunteer and a participant, practising a language, learning or working through a career question. Volunteers contribute their time and expertise freely.
TEEI's platform handles matching, scheduling, attendance verification and impact reporting. Routine coordination is handled by software, rather than by paid staff coordinating each session. This is how volunteer time becomes a delivered, documented session without a separate layer of paid administration for every meeting.
That is the model behind the figure: people contribute the time and expertise; the platform provides the infrastructure around them. The cost per verified impact hour measures the running costs supporting that contribution, not the value of the volunteer's time.
Safeguarding reports are reviewed by people, not software.
In September 2026, TEEI's own platform delivered 439.2 verified hours across 670 sessions. The included AWS video and platform infrastructure costs were $343.14 before cloud credits:
$343.14 ÷ 439.2 verified hours = $0.78 per verified impact hour.
AWS supports the infrastructure through cloud credits. The calculation shows the cost before those credits, rather than the amount TEEI pays after that support. The programmes are free to take part in.
Below, you can inspect the reporting period, verified hours, included costs and calculation behind the figure.
1. The period and the hours
The period is the last full calendar month, in UTC. The hours are the verified hours of the sessions that took place in that same period: a session is counted in the month it started, as everywhere on the Impact Board. A verified hour is measured only while both participants were present on video, as the session measurement method describes.
- Period
- 1 Sep 2026 00:00 to 1 Oct 2026 00:00 UTC, 30 days
- Sessions
- 670
- Verified hours
- 439.2
2. The costs included
The AWS charges for the same days, as Cost Explorer reports them, grouped by service and region: the video service that carries the sessions, and the infrastructure that runs the platform in production, allocated in full to the sessions. Nothing else in the AWS account is part of the figure.
| Service | Region | USD |
|---|---|---|
| Video the sessions | 262.89 | |
| Amazon Chime Features | eu-central-1 | 151.15 |
| Amazon Chime | eu-central-1 | 111.73 |
| Infrastructure runs the platform in production | 80.25 | |
| AmazonCloudWatch | eu-west-1 | 35.58 |
| Amazon Simple Storage Service | eu-west-1 | 9.75 |
| AWS Lambda | eu-west-1 | 8.77 |
| AWS Secrets Manager | eu-west-1 | 8.66 |
| AWS Key Management Service | eu-west-1 | 5.41 |
| Amazon Inspector | eu-west-1 | 4.67 |
| AWS Elemental MediaConvert | eu-west-1 | 3.85 |
| Amazon Transcribe | eu-west-1 | 1.35 |
| AWS Secrets Manager | eu-central-1 | 0.77 |
| AmazonCloudWatch | eu-central-1 | 0.59 |
| AWS End User Messaging | eu-west-1 | 0.26 |
| AWS Step Functions | eu-west-1 | 0.24 |
| AWS End User Messaging | eu-central-1 | 0.17 |
| Amazon Simple Storage Service | eu-central-1 | 0.11 |
| Amazon API Gateway | eu-west-1 | 0.03 |
| Amazon Polly | eu-west-1 | 0.02 |
| CloudWatch Events | eu-west-1 | 0.01 |
| Included in the figure, before credits | 343.14 | |
| Subtotals are summed before rounding. Lines under $0.01 are in the subtotals but not listed. | ||
3. The calculation
cost per verified impact hour
= (video 262.89 + infrastructure 80.25) USD / 439.2 h
= 343.14 / 439.2 = 0.78 USD
4. Before credits
All amounts are gross usage as Cost Explorer reports it with the record type Usage, before any credit is applied. AWS supports TEEI's infrastructure through cloud credits. They are not subtracted here, because the figure is meant to show what the infrastructure costs, not what TEEI paid.
5. Updates and data
A scheduled job reads the AWS costs and the verified hours once a day and stores each reading with the time it was read. The Impact Board and this page show the same stored reading; no visitor triggers a reading. The period moves to the next month on the third day after the month ends, when AWS has settled the month's charges. If a source does not answer, the previous reading stands with its time. A published reading is not rewritten.
- Live reading
/api/impact-cost.json- Session method
/about/impact/methodology/sessions/