Reference
Events per second, event size, retention, and a compression ratio. The monthly footprint, before anyone argues about the vendor.
Runs in your browser. Nothing you type is uploaded.
Quick answer
Stored bytes = events per second × bytes per event × 86,400 × retention days ÷ compression ratio. 2,000 events/s at 1,200 bytes, kept 30 days, compressed 4:1, is 1,555.2 GB. At $0.023 per decimal GB-month that is $35.77. The same bytes are 1,448.392868 GiB, or $33.31 if the vendor bills 2^30-byte gigabytes.
The formula
Start from the event, not from a feeling about “a lot of logs.” Bytes per day = events/s × event bytes × 86,400. Multiply by the retention window. That product is the raw footprint: the data you would store if you kept every byte. Divide by the compression ratio. A ratio of 4 means you keep a quarter. Then multiply the stored gigabytes by the price per GB-month.
The footprint levels off. You are not billed for every byte ever written. You are billed for the window you chose to keep. Doubling retention roughly doubles the bill. Halving the event size does the same in the other direction. Compression only helps if the ratio is real for that payload.
A worked example
The default inputs are a busy API: 2,000 events a second, 1,200 bytes each, 30 days, a 4:1 ratio, $0.023 per GB-month. That is 172,800,000 events a day and 207.36 GB of raw ingest a day. Over 30 days the raw footprint is 6,220.8 GB. After 4:1 compression, 1,555.2 GB remain. Uncompressed, the same window is $143.08. Compressed, $35.77 if the gigabyte is decimal.
Decimal GB and billed GiB
Some vendors define the billed gigabyte as 2^30 bytes. 1,555.2 decimal GB is 1,448.392868 GiB, and $0.023 × that figure is $33.31. The estimator prints both so a pricing page cannot change the answer in a footnote. Read the vendor’s definition of GB before you pick a column. The MB to GB converter is the same distinction without the events.
What the ratio is
Enter how many times smaller the stored data is. JSON logs often compress somewhere around 4:1 to 10:1 with a general-purpose codec, and much more once they are columnar and sorted. If you measured a 75% reduction, the stored size is 25% of raw, so the ratio is 4. A number below 1 makes the data larger. The form will say so instead of quietly inflating the bill.
S3 storage cost calculator
Object storage such as Amazon S3 is billed per GB-month, and the rate depends on the region and the storage class. Requests, retrieval and data transfer are billed separately. Enter the per-GB price from your provider’s current pricing page in the price field, and the estimator applies it to the stored gigabytes in both decimal GB and binary GiB.
Questions
How do I estimate log storage cost?
Multiply events per second by the average event size in bytes, by 86,400, and by the retention in days. Divide by the compression ratio. Multiply the resulting gigabytes by your price per GB-month.
Should the compression ratio be 4 or 0.25?
Use 4 for 4:1 compression. The stored size is the raw size divided by the ratio. 0.25 would make the stored data four times larger.
Does a longer retention cost more forever?
It costs more for as long as you keep the longer window. The bill tracks the footprint, which stabilizes at events × size × window, not at the lifetime sum of everything ingested.
Is $0.023 the right price?
It is a common on-demand object-storage example, not a quote. Replace it with the figure on your pricing page, including retrieval if you actually read the logs back.
How much does S3 storage cost per GB?
There is no single price. It varies by region and storage class and changes over time, and requests, retrieval and transfer are billed separately. Read the current number from the provider’s pricing page, enter it as the price per GB-month, and the estimator shows the monthly cost for both GB and GiB billing.