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Token limits, context rot, compaction cliffs and the productivity math vendors keep postponing.
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Context Compaction Calculator
A context window goes in, a summary comes out. This calculator shows the survival rate, the share of context discarded and what it costs to re-read the state that dropped. The defaults mirror the measured 575k-to-4.3k median.
Every result on this page is pre-rendered with the default inputs, so the numbers are readable with JavaScript off. Results update as you type and nothing leaves your browser. Part of the Buildopsy engineering calculators.
A context window goes in, a summary comes out. See what survives and what the re-read bill looks like. Defaults mirror the measured median: 575k crushed to about 4.3k, then roughly 28 steps of re-reading.
Live result · Re-read bill
· What it costs to rebuild state after the window gets crushed.
Re-read bill
$2.07
steps × cost per step
Window fate
0.8%survived
- Survived
- Lost
Summary size
4,313 tokens survive
tokens that survive
Context lost
99.25% of context lost
share of the window
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