Projections & Profitability
This page covers the empirical cost model, per-user economics, tiered cost estimates, and breakeven analysis. For infrastructure line items, see Infrastructure.
Empirical Cost Model
Assumptions
Based on SaaS industry benchmarks and trading platform characteristics:
| Parameter |
Value |
Rationale |
| Pareto (80/20) |
20% power users drive 80% of compute |
Industry standard |
| DAU/MAU |
50% of subscribers active daily |
Conservative SaaS benchmark |
| Peak concurrency |
35% of total users running workers |
DAU × 70% peak online |
| Worker idle timeout |
30 minutes |
Balances cost vs UX |
| Pool startup |
897ms |
Sub-second, transparent to users |
Market Coverage (~20 hr/day)
00 02 04 06 08 10 12 14 16 18 20 22 24 (UTC+8)
├─────────────────────── Crypto 24/7 ────────────────────────────────┤
├── TW Night ──┤ ├──── TW Night Session ────────┤
├── TW Day ──┤
├── US Market ────┤
Peak workers = Total users × 0.50 (DAU) × 0.70 (peak) = 0.35 × N
Peak instances = ⌈ 0.35N / workers_per_instance ⌉
Off-peak inst. = max(1, ⌈ 0.05N / workers_per_instance ⌉)
Daily instance-hours:
Peak (8 hr): peak_instances × 8
Off-peak (16 hr): off_peak_instances × 16
Monthly cost = daily_instance_hours × 26 days × $0.152/hr
Example: 100 Users
Peak: 35 workers → 2 instances × 8 hr = 16 instance-hr/day
Off-peak: 5 workers → 1 instance × 16 hr = 16 instance-hr/day
Daily: 32 instance-hours
Monthly: 32 × 26 × $0.152 = $127
Per-user: $1.27/month
Per-User Unit Economics
| Model |
Per-User Cost |
Gross Margin (NT$999) |
Use Case |
| Worst case (24/7) |
$2.79/mo (NT$89) |
91.1% |
Theoretical upper bound |
| Empirical (Pareto) |
$1.27/mo (NT$41) |
96.0% |
Operating estimate |
| Best case (low activity) |
$0.60/mo (NT$19) |
98.1% |
Low engagement |
Tiered Cost Estimates
All-In Monthly Cost by Tier
| Tier |
Peak EC2 |
Total Cost (USD) |
Per-User |
Revenue (TWD) |
Net Margin |
| 10 |
1 (fixed) |
$447 |
$44.70 |
NT$9,990 |
-43% |
| 15 |
1 (fixed) |
$447 |
$29.80 |
NT$14,985 |
Breakeven |
| 30 |
1 (fixed) |
$447 |
$14.90 |
NT$29,970 |
52% |
| 100 |
2 |
$512 |
$5.12 |
NT$99,900 |
84% |
| 500 |
6 |
$1,055 |
$2.11 |
NT$499,500 |
93% |
| 1,000 |
12 |
$1,815 |
$1.82 |
NT$999,000 |
94% |
| 5,000 |
15 (2xl) |
$4,270 |
$0.85 |
NT$4,995,000 |
97% |
| 10,000 |
15 (4xl) |
$8,024 |
$0.80 |
NT$9,990,000 |
97.4% |
| 50,000 |
37 (8xl) |
$30,500 |
$0.61 |
NT$49,950,000 |
98% |
| 100,000 |
73 (8xl) |
$56,500 |
$0.57 |
NT$99,900,000 |
98.2% |
Detailed Breakdown: 10,000 Users
| Component |
Spec |
Monthly (USD) |
| EC2 Workers |
15 × r6i.4xlarge (peak) |
$4,331 |
| API EC2 |
4 × m6i.xlarge (16 tasks) |
$700 |
| ALB |
~60 LCU |
$365 |
| Lambda Orchestrator |
~10M invocations |
$100 |
| ElastiCache Valkey |
Serverless 10 GB, 100K ECPU |
$1,000 |
| RDS Aurora + Proxy |
db.r6g.xlarge (Multi-AZ + replica) |
$950 |
| CloudWatch |
Full monitoring |
$200 |
| WAF + Shield |
Advanced security |
$150 |
| Other |
VPC Endpoint, Secrets, ECR, backup |
$228 |
| Total |
|
$8,024 |
Revenue & Profitability
Annual Projections
| Users |
Annual Revenue (TWD) |
Annual Cost (TWD) |
Annual Profit (TWD) |
Net Margin |
| 100 |
NT$1,198,800 |
NT$196,608 |
NT$1,002,192 |
83.6% |
| 500 |
NT$5,994,000 |
NT$405,120 |
NT$5,588,880 |
93.2% |
| 1,000 |
NT$11,988,000 |
NT$696,960 |
NT$11,291,040 |
94.2% |
| 5,000 |
NT$59,940,000 |
NT$1,639,680 |
NT$58,300,320 |
97.3% |
| 10,000 |
NT$119,880,000 |
NT$3,081,216 |
NT$116,798,784 |
97.4% |
Breakeven Analysis
Fixed costs (regardless of user count):
EC2 Worker (r6i.large × 1): $111/month (always-on baseline)
API EC2 (m6i.large × 1): $88/month
ElastiCache Valkey Serverless: $91/month (1 GB minimum)
RDS Aurora + Proxy: $100/month
Lambda Orchestrator: $8.50/month
VPC Endpoint (3 AZs): $28/month
Other: $20/month
──────────────────────────────────────
Total fixed: ~$447/month = NT$14,304
Breakeven: NT$14,304 ÷ NT$999 = 14.3 → 15 paying users
See Optimization for Reserved Instances, Graviton, and Spot strategies.