Datadog Log Retention Cost: 15-Day vs 30-Day Pricing at 100 GB a Month

Datadog splits a log bill into two lines that are priced in different units, and the retention window only moves the second one. Ingest is $0.10 per GB. Indexing, the part that makes logs searchable, is charged per million events per month at a rate that depends on how long you keep them: $1.70 at 15-day retention and $2.50 at 30-day retention on annual billing, or $2.55 and $3.75 on-demand. A hundred gigabytes a month costs $10 to bring in, and what happens after that depends entirely on how many events those gigabytes hold.

Retention rates per million log events per month

Log ingest is a separate line at $0.10 per GB on every billing type (checked 2026-10-25).

What 100 GB a month bills at each retention window

Totals add the $10 monthly ingest charge to the indexing line (calculated 2026-10-25).

What the numbers actually mean

Retention is a per-event decision, so its cost depends on log volume rather than log size. Doubling the window from 15 to 30 days raises the per-million rate from $1.70 to $2.50, which is 47% more for twice the searchable history (calculated 2026-10-25). That is a mild step compared with the four-tier ladder as a whole: 3-day retention at $1.06 is 38% below the 15-day rate and 58% below the 30-day rate.

The per-GB number is the least important figure on the page. At $0.10 per GB, a hundred gigabytes a month is $10, which is smaller than any realistic indexing line: the same hundred gigabytes holding 10 million events costs $17 a month to index at 15 days and $25 at 30 days (calculated 2026-10-25). Teams that budget from the ingest rate underestimate the bill by an order of magnitude, because ingest is priced per gigabyte and indexing is priced per event.

Event size is the hidden variable. Datadog publishes no bytes-to-events conversion, so two accounts shipping the same 100 GB can differ by a factor of ten in cost depending on whether that volume is verbose debug lines or compact JSON. The only reliable way to forecast is to count events in a sample of the actual stream, then multiply by the retention rate. A 100 GB stream of 1 KB events is roughly 100 million events and bills $180 a month at 15-day retention (calculated 2026-10-25); the same 100 GB in 10 KB events is 10 million and bills $27.

Flex Storage changes the shape of long retention. Storing logs at $0.05 per million events per month, with a one-month minimum, is 50 times cheaper per million events than 30-day indexing at $2.50 (calculated 2026-10-25), and it is designed for logs you need to keep but rarely query. The catch is that querying stored logs requires rehydration, and the page prices rehydration as scans at $0.10 per compressed GB.

How we measured it

Rates come from the Datadog pricing page and price list fetched on 2026-10-25, where the Standard Indexing card lists retention options of 3, 7, 15 and 30 days and the per-million-event rates appear in the page's embedded price data with annual, month-to-month and on-demand variants. No logs were ingested, no index was created and no trial was started. Event totals, totals including ingest and percentage differences are arithmetic on published rates and are labelled calculated.

What changes in practice

Decide retention per index, not per account. Because the 3-day rate is $1.06 against $2.50 for 30 days, routing debug logs to a short window and keeping only audit and error logs at 30 days is worth 58% on the events that move (calculated 2026-10-25).

Sample before you ship. Ingest at $0.10 per GB is cheap enough that volume feels free, but indexing multiplies by event count, so dropping noisy debug lines at the agent is the highest-leverage saving in the whole pipeline.

Use Flex Storage for compliance tails. At $0.05 per million events stored, a month of 10 million archived events costs $0.50 against $25 to index them for 30 days (calculated 2026-10-25), provided you accept rehydration before you can query them.

Bottom line

A hundred gigabytes a month costs $10 to ingest and between $27 and $260 a month in total depending on event count and retention (calculated 2026-10-25). Set 15-day retention unless a query needs otherwise: the 30-day window costs 47% more per event and rarely earns it back.