StackCalcs blog
Calculator guides and worked examples
Understand the inputs, work through a scenario, and check what an estimate leaves out before using it for a decision.
AWS
- ALB pricing: turn hourly capacity into monthly LCU-hours
- API Gateway HTTP API pricing: requests vs billable units
- Aurora Serverless v2 pricing: calculate average ACU-hours
- Aurora Standard vs I/O-Optimized: compare the complete subtotal
- AWS egress pricing: build a tiered monthly transfer estimate
- CloudFront cache hits: what they change in your cost estimate
- CloudFront pricing: estimate bandwidth and HTTPS request costs
- CloudWatch log retention vs ingestion: which change saves money?
- CloudWatch Logs pricing: estimate ingestion from log volume
- DynamoDB index costs: budget write amplification explicitly
- DynamoDB pricing: convert item size into request units
- EBS gp3 pricing: separate storage, IOPS, and throughput
- EC2 business-hours scheduling: calculate the compute savings
- EC2 On-Demand vs Reserved Instances vs Savings Plans
- EC2 Reserved Instances: amortize upfront payment correctly
- EKS cluster consolidation: estimate fixed fees and limits
- EKS pricing: separate cluster fees from worker nodes
- ElastiCache pricing: count primaries, replicas, and node-hours
- Estimate a serverless API budget from users and polling
- Estimate download egress from file size and user activity
- Fargate pricing: calculate task CPU and memory hours
- Fargate rightsizing: compare task size and runtime together
- How EC2 pricing actually works
- Is an ElastiCache cache worth its cost? A break-even worksheet
- Lambda memory tuning: find the duration break-even
- Lambda pricing: calculate requests and GB-seconds
- NAT Gateway pricing: separate gateway hours from processed data
- NAT Gateway vs VPC endpoints: calculate the traffic break-even
- NLB pricing: estimate NLCU-hours from measured capacity
- NLB TCP and TLS costs: what to measure before comparing
- RDS MySQL pricing: calculate the instance-hour subtotal
- RDS rightsizing: compare instance cost without losing headroom
- S3 cold storage: check small objects and retention before moving data
- S3 small files: why object count and request patterns matter
- S3 Standard pricing: estimate storage and request costs
- S3 Standard vs Standard-IA: calculate retrieval break-even
- Savings Plans effective rate: test unused commitment risk
- Savings Plans sizing: separate steady demand from bursts
- Unused EBS volumes: estimate savings before removing storage
- Why a low-traffic ALB still has a monthly cost
Google Cloud
- Avoid unused Compute Engine commitment spend
- Build a GCP egress forecast from traffic data
- Calculate a Compute Engine committed use discount break-even
- Choose a Cloud Storage class with retention math
- Compare Cloud SQL high availability cost
- Compare Cloud Storage class cost by access pattern
- Compare GKE Autopilot and Standard cost
- Estimate a Cloud NAT monthly cost
- Estimate a Cloud Storage monthly cost
- Estimate a Compute Engine monthly cost
- Estimate AlloyDB cost
- Estimate Artifact Registry cost
- Estimate BigQuery query cost from bytes scanned
- Estimate BigQuery storage cost separately
- Estimate Cloud CDN cost from hits and misses
- Estimate Cloud Load Balancing cost
- Estimate Cloud Run cost from instance time
- Estimate Cloud SQL monthly cost
- Estimate Cloud Storage operation cost
- Estimate GCP network egress by destination
- Estimate GKE cost components
- Estimate Memorystore cost
- Estimate Persistent Disk and Hyperdisk billing
- Estimate Pub/Sub cost from message throughput
- Forecast AlloyDB read-pool cost
- How BigQuery on-demand pricing works
- How Cloud Run concurrency changes cost
- How partitioning and clustering reduce BigQuery bytes scanned
- How Pub/Sub message size affects cost
- Reduce Artifact Registry transfer cost with location
- Reduce surprises in Cloud NAT cost forecasts
- Right-size Hyperdisk performance cost
- Right-size Memorystore capacity cost
- Use cache ratio to forecast Cloud CDN cost
- What changes a Compute Engine cost estimate
- What drives Cloud Load Balancing cost
Cloud comparisons
- AWS CloudFront vs GCP Cloud CDN: what to compare before choosing
- AWS EC2 vs GCP Compute Engine: what to compare before choosing
- AWS EKS vs GCP GKE: what to compare before choosing
- AWS Fargate vs GCP Cloud Run: what to compare before choosing
- AWS Lambda vs GCP serverless: what to compare before choosing
- AWS NAT Gateway vs GCP Cloud NAT: what to compare before choosing
- AWS RDS vs GCP Cloud SQL: what to compare before choosing
- AWS S3 vs GCP Cloud Storage: what to compare before choosing
- AWS vs GCP egress: model the same data transfer
- AWS vs GCP egress: what to compare before choosing
- AWS vs GCP GPU cost: what to compare before choosing
- AWS vs GCP Kubernetes cost: what to compare before choosing
- CloudFront vs Cloud CDN: estimate delivery cost
- EC2 vs Compute Engine: compare a monthly VM estimate
- EKS vs GKE: estimate control-plane and worker cost
- How to estimate AWS Fargate vs GCP Cloud Run costs
- How to estimate AWS Lambda vs GCP serverless costs
- How to estimate AWS vs GCP GPU cost costs
- How to estimate AWS vs GCP Kubernetes cost costs
- NAT Gateway vs Cloud NAT: compare processed traffic
- RDS vs Cloud SQL: build a comparable database estimate
- S3 vs Cloud Storage: estimate storage capacity cost
AI
- AI Agent Cost per Run: A Step-by-Step Estimate
- AI Agent Pricing Models: Cost per Run, Task, or Outcome?
- GPU vs API Break-Even: Calculate the Required Throughput
- How to Calculate Monthly LLM API Cost from Token Usage
- How to Estimate Prompt Caching Savings from Cache Hits
- LLM API Pricing Comparison by Cost per Successful Task
- Managed RAG vs DIY: Which Costs Belong in the Comparison?
- RAG Cost Estimate for Ingestion and Answer Generation
- Self-Hosted GPU vs Model API: A Practical Cost Decision
- When Prompt Caching Pays Off—and When It Does Not
Startup and SaaS
- ARR formula: convert monthly recurring revenue to ARR
- ARR vs annual revenue when a SaaS business is growing
- Blended CAC vs channel CAC: avoid averaging ratios
- Break-even point formula in units and revenue
- Customer acquisition cost formula with a worked example
- Customer churn rate formula: use the starting customer base
- Customer LTV formula: include gross margin and monthly churn
- Gross vs net burn rate: formulas and a cash example
- How discounts change your break-even sales volume
- How equity dilution works when new shares are issued
- How hiring changes startup runway: three cash scenarios
- How successive funding rounds compound founder dilution
- How to calculate startup runway from cash and net burn
- How to compare startup burn-rate reductions
- LTV:CAC ratio formula and what a 3-to-1 result means
- LTV:CAC ratio vs CAC payback: same ratio, different cash risk
- Monthly recurring revenue formula with expansion and churn
- Monthly vs annual churn: why multiplying by 12 misleads
- MRR vs cash collected: how annual plans change the picture
- Post-money SAFE ownership before and after a new round
- Post-money SAFE ownership: investment divided by cap
- SaaS enterprise value vs equity value: a simple bridge
- SaaS valuation formula: ARR times an assumed multiple
- Why small churn changes can move estimated LTV sharply
Career and compensation
- Calculate remaining notice days from a contract period
- Calculate take-home pay from CTC with explicit deductions
- Contractor vs Employee Calculator: assumptions to check
- CTC offer checklist before estimating take-home pay
- Freelancer Rate Calculator: assumptions to check
- Hourly to Annual Salary Calculator: assumptions to check
- How to use a Contractor vs Employee Calculator
- How to use a Freelancer Rate Calculator
- How to use a Hourly to Annual Salary Calculator
- How to use a Job Offer Comparison Calculator
- How to use a RSU Compensation Calculator
- How to use a Salary Hike Calculator
- Job Offer Comparison Calculator: assumptions to check
- Notice Period Calculator: assumptions to check
- RSU Compensation Calculator: assumptions to check
- Salary Hike Calculator: assumptions to check