Setting the file. One moment.
Chapter 33 · Exploring LLM Costs
Subchapter 33.4
references/cost-sources.mdMarkdown3 KBView on GitHub
Costs can arrive on the event in three ways; ingestion applies them in this precedence (see Calculating LLM costs for the authoritative rules):
$ai_input_cost_usd,
$ai_output_cost_usd, $ai_request_cost_usd, $ai_web_search_cost_usd
directly. Ingestion preserves them and fills $ai_total_cost_usd as the
sum. Use when the caller already knows the cost.$ai_input_token_price /
$ai_output_token_price (required pair) plus optionally
$ai_cache_read_token_price, $ai_cache_write_token_price,
$ai_request_price, $ai_web_search_price. Ingestion multiplies by the
token counts. Token prices are per token, not per million.$ai_model + $ai_provider (OpenRouter first, manual fallback).Three metadata properties tell you which path was taken — read them whenever a cost looks wrong:
| Property | Meaning |
|---|---|
$ai_model_cost_used | Canonical model id the pricing lookup matched (may differ from $ai_model) |
$ai_cost_model_source | openrouter | manual | custom | passthrough |
$ai_cost_model_provider | Provider the lookup used |
When $ai_total_cost_usd is null or zero for a model, group by model
and $ai_cost_model_source so you can see, per model, how many of
its zero-cost calls came from each ingestion path. A model that has only
source = NULL rows means ingestion never matched a pricing entry (fix:
add custom pricing or correct $ai_model / $ai_provider); a model
with source = 'custom' and zero cost is an explicitly-zero custom
price (usually a misconfigured $ai_input_token_price / $ai_output_token_price).
Without the source grouping the two look the same.
posthog:execute-sql
SELECT
properties.$ai_model AS model,
properties.$ai_cost_model_source AS source,
count() AS calls,
countIf(toFloat(properties.$ai_total_cost_usd) = 0 OR properties.$ai_total_cost_usd IS NULL) AS zero_cost_calls
FROM events
WHERE event = '$ai_generation'
AND timestamp >= now() - INTERVAL 7 DAY
GROUP BY model, source
ORDER BY zero_cost_calls DESC