Session Date: January 20, 2026
Key Finding: Week 3 January showed 81% cost reduction per session vs Week 2
The Discovery
While analyzing Claude Code usage from December 2025 through January 2026, a dramatic efficiency improvement emerged:
| Week |
Sessions |
Est. Cost |
Cost/Session |
vs Week 2 |
| Week 1 (Jan 1-7) |
3 |
$37.25 |
$12.42 |
-35% |
| Week 2 (Jan 8-14) |
58 |
$1,114.77 |
$19.22 |
baseline |
| Week 3 (Jan 15-20) |
157 |
$571.25 |
$3.64 |
-81% |
What Changed
Session Strategy Shift
| Metric |
December |
January (Week 3) |
Change |
| Avg Sessions/Day |
7.3 |
26.2 |
+259% |
| Tokens/Session |
40,246 |
6,503 |
-84% |
| Cost/Session |
$22.17 |
$3.64 |
-84% |
The Pattern
December: Fewer, longer sessions (avg 40K tokens each)
└── Context grows large → expensive
January: More, shorter sessions (avg 6.5K tokens each)
└── Context stays small → efficient
Evidence: Spike Day Comparison
Research Days (High Cost)
| Day |
Sessions |
Tokens |
Tokens/Session |
Type |
| Dec 14 |
27 |
1.08M |
39,922 |
Research |
| Dec 24 |
14 |
835K |
59,628 |
Research |
| Jan 11 |
22 |
1.38M |
62,533 |
Research |
Implementation Days (Low Cost)
| Day |
Sessions |
Tokens |
Tokens/Session |
Type |
| Jan 17 |
16 |
104K |
6,517 |
Implementation |
| Jan 19 |
83 |
499K |
6,008 |
Rapid iteration |
Jan 19’s 83 sessions = deliberate context resets maintaining low cost/session
Cost Impact
Monthly Efficiency
| Metric |
December |
January |
Improvement |
| Total Cost |
$1,951.10 |
$1,723.27 |
-12% |
| Messages |
28,909 |
81,379 |
+181% |
| Cost/Message |
$0.067 |
$0.021 |
-69% |
| Cost/Session |
$22.17 |
$7.90 |
-64% |
What This Means
- Same daily spend (~$157/day both months)
- 3x more work completed in January
- 69% more efficient per interaction
Root Causes
1. Shorter Sessions = Smaller Context
Context window cost is proportional to:
Cache Write (1.25x input rate) + Cache Read (0.1x input rate)
Smaller context → Less cache write → Lower cost
2. Research vs Implementation Ratio
| Activity |
Tokens/Message |
Cost Efficiency |
| Research |
100-150 |
Low |
| Implementation |
4-5 |
High |
Week 3 was implementation-heavy → efficient
3. Deliberate Context Management
- Frequent
/clear or new sessions
- Avoiding context bloat
- Compacting before 70% utilization
Implementation: Context Tracking
To maintain visibility into this optimization, context tracking was added:
New Metrics (SigNoz)
| Metric |
Description |
session.context.size |
Tokens at session start |
session.context.utilization |
% of 200K window used |
Visual Indicator
📊 Context: 45K tokens (22.5%)
[████░░░░░░░░░░░░░░░░] 🟢 (green < 50%)
[██████████░░░░░░░░░░] 🟡 (yellow 50-70%)
[██████████████░░░░░░] 🔴 (red > 70%)
Historical Tracking
~/.claude/context-history.json — session-by-session data- Daily averages for trend analysis
- Automatic cleanup (keeps last 1000 sessions, 90 days)
Recommendations
Maintain the Gains
- Keep sessions short — Target <10K tokens/session
- Reset frequently — New session after major task completion
- Compact at 70% — Don’t let context hit limits
- Monitor trends — Watch
session.context.utilization in SigNoz
Optimize Further
- Batch research — Dedicate specific sessions to exploration
- Use subagents — Delegate verbose operations (Sonnet usage up 11x)
- Truncate output —
| tail -30 for logs, use offset/limit for files
Summary
| Before (Dec) |
After (Jan Week 3) |
Result |
| Long sessions |
Short sessions |
-84% tokens/session |
| Rare resets |
Frequent resets |
-81% cost/session |
| 7 sessions/day |
26 sessions/day |
3x throughput |
| $22/session |
$3.64/session |
$18.50 saved/session |
Total Potential Savings: At 20 sessions/day, this strategy saves ~$370/day vs old patterns.
Session documented: January 20, 2026
Full analysis: 2026-01-20-claude-usage-analysis.md
