Every calculator, grouped by category. Each one shows its formula, assumptions and worked examples.
PayPal Fee
PayPal fee calculator for US accounts: see the fee and what you receive for checkout, cards, Venmo, goods and services and international payments, or how much to charge.
Stripe Fee
Stripe fee calculator for US accounts: card, in-person and ACH fees with international, currency conversion and manual-entry surcharges, plus how much to charge.
Markup
Markup calculator: find the selling price from cost and markup, the markup from cost and price, or the price that hits a target margin — with markup vs margin explained.
Commission
Commission calculator for flat-rate and tiered plans: sales commission, your share after a split, total pay with base salary, and the sales needed to hit a target.
Food Cost
Food cost calculator for restaurants: plate cost and food cost percentage for a menu item, a menu price for your target food cost, or period food cost from inventory.
Wire Size
Wire size calculator using NEC Table 310.16 ampacity and Chapter 9 voltage drop: minimum AWG/kcmil for copper or aluminum by amps, voltage, distance and phase.
Amps
Amp calculator: convert watts, kW, kVA or horsepower to amps (or amps to watts) for DC, single-phase and three-phase AC, with power factor, efficiency and formulas.
Energy Cost
Energy cost calculator: enter watts, hours of use and your electricity rate to see kWh and running cost per hour, day, month and year for any appliance or device.
OpenAI Cost
Calculate the exact cost of OpenAI API calls by model. Enter input and output tokens to estimate GPT-4o, o1, and GPT-3.5 pricing instantly — no sign-up required.
JSON Size
Instantly calculate the byte size and KB of any JSON string. Validates syntax in real time. Essential for API payload optimization and size limit checks.
429 Too Many Requests
What a 429 actually means, how to read Retry-After in both of its forms, and why a client can hit one while apparently still under the rate limit.
Base64 Size
Calculate Base64 encoded size from original bytes. See the exact output size and ~33% overhead — instant results for API payloads, images, and JWT tokens.
Cron Next Run
Calculate the next run times for any cron expression instantly. Enter your cron schedule and start time to see exactly when your job will execute next
Latency Budget
Calculate your latency budget across service components. Allocate ms targets for each layer and instantly see remaining headroom or where you're over budget
Cache Hit Rate
Calculate cache hit rate instantly — enter total requests and cache hits to get hit %, miss %, and origin load. Works for CDN, Redis, Memcached, and browser caches.
QPS
Calculate QPS (queries per second) from request volume and time window. Estimate average and peak throughput for API capacity planning — no sign-up required
Throughput
Calculate throughput in requests per second and MB/s from total requests and time window. Instant API and system capacity planning — no sign-up required.
Little's Law
Little's Law is L = λW. What each term means, why it holds for any stable queue whatever the distributions, and the saturated case where it quietly lies.
Bandwidth Cost
Calculate bandwidth cost by entering monthly transfer volume and price per GB. Instant egress cost estimates for AWS, GCP, Azure, Cloudflare, and major CDN providers.
Storage Cost
Use this storage cost calculator to estimate monthly and total cloud storage spend. Enter data size, price per GB, and duration for an instant result.
Transfer Cost
Calculate data transfer cost by provider with this free data transfer cost calculator. Enter volume, price per GB, and free tier to get instant egress estimates.
Payload Size
Estimate API payload size in bytes, KB, or MB. Enter record count and average record size to calculate request payload, gzip estimate, and daily data volume.
HTTP Request Size
Calculate HTTP request size in bytes instantly. Enter method, URL length, headers, and body to estimate total payload size for API calls, gateways, and load balancers.
Regex Performance
Regex performance calculator — analyze any pattern for ReDoS risk, O(n) to O(n3) time complexity, and estimated execution time per run in milliseconds.
SQL Query Cost
Estimate SQL query costs on BigQuery, Athena, or Redshift Spectrum. Enter data scanned and query volume to instantly project your monthly database spend.
Pagination Perf
Calculate pagination performance for offset vs cursor-based queries. Enter total records, page size, and page number to see query time slowdown instantly.
Index Size
Index size calculator: instantly estimate how large a B-tree database index will grow given row count, key size, page size, and fill factor — no DBA needed.
Thread Pool Size
Calculate the optimal thread pool size for your application using CPU cores, utilization target, and I/O wait time. Based on the Brian Goetz formula.
Queue Throughput
Calculate worker queue throughput instantly — enter worker count, task duration, and queue size to see tasks/sec rate and queue drain time for any worker pool
Retry Backoff
Calculate exponential retry backoff delays for your API calls. Enter initial delay, multiplier, and max retries to see per-attempt wait times and total retry budget instantly.
Timeout
Calculate the optimal timeout value for API calls and network requests. Enter P99 latency and a safety multiplier to get a recommended timeout instantly.
Response Time
Estimate API response time by combining network latency, server processing, payload transfer, and middleware overhead — results in milliseconds, no sign-up needed
Compression Ratio
Calculate compression ratio instantly — enter original and compressed file sizes to get the ratio, space savings percentage, and bytes saved. Works for any format
Upload Time
Use this file upload time calculator to estimate how long any upload takes — enter file size and connection speed for an instant result, no sign-up needed.
Download Speed
Download speed calculator — enter file size (MB) and connection speed (Mbps) to estimate exact download time. Works for any file type or network speed
TLS Handshake
Calculate TLS handshake time for TLS 1.2 and TLS 1.3 by entering your network RTT and certificate validation overhead. Optimize HTTPS latency before shipping.
CDN Cost
Calculate your monthly CDN cost by data transfer and requests. Estimate CloudFront, Cloudflare, and Fastly pricing instantly — no sign-up required.
Lambda Cost
Calculate AWS Lambda monthly costs by memory, duration, and invocations. Estimate execution and request charges instantly — no sign-up required.
K8s Resources
Calculate Kubernetes resource requests and limits across pods. Enter replicas, CPU millicores, and memory MiB to plan cluster capacity and avoid OOMKill or throttling.
Pod Capacity
Calculate how many pods fit on a Kubernetes node using CPU and memory requests. Instantly find your scheduling bottleneck — no cluster access required.
CPU Usage
Estimate CPU usage percentage from requests per second, CPU time per request, and core count. Free cpu usage estimator for backend capacity planning.
Memory Usage
Calculate memory usage for any dataset or data structure. Enter item count, bytes per item, overhead %, and replicas to get total RAM requirements instantly.
Disk IOPS
Calculate disk IOPS from seek time, RPM, block size, and transfer rate. Instantly estimate HDD and SSD storage performance — no sign-up required.
RAID Capacity
Calculate RAID storage capacity for RAID 0, 1, 5, 6, and 10 arrays. Enter disk count and size to see usable capacity and storage efficiency instantly
Cache TTL
Use the cache TTL impact calculator to estimate hit rate, origin load reduction, and monthly bandwidth savings for your CDN or application cache configuration
Event Rate
Calculate the event processing rate for your pipeline. Enter worker count, per-event latency, and total events to get throughput and queue drain time instantly
Queue Delay
Calculate message queue delay with this free calculator. Enter queue depth, consumer rate, and latency to estimate end-to-end delay instantly — no sign-up
Batch Processing Time
Batch processing time calculator: given item count, processing rate, and workers, calculate total job duration instantly in seconds, minutes, or hours
API Pagination
Calculate total pages, fetch time, and request count for paginated API calls. Enter total records, page size, and rate limit to plan your data sync instantly.
Token Bucket
Calculate token bucket rate limits instantly. Enter bucket capacity, refill rate, and request cost to find max RPS, burst capacity, and wait time for blocked requests.
Leaky Bucket
Calculate leaky bucket rate limiting: effective throughput, drop rate, and bucket fill time from incoming request rate, leak rate, and bucket capacity.
Hash Collision
Calculate hash collision probability for any hash function size. Enter item count and bit width to estimate birthday problem collision risk instantly.
Encryption Overhead
Encryption overhead calculator: measure AES-256-GCM, AES-128-GCM, AES-256-CBC, and ChaCha20 ciphertext size, overhead bytes, and encryption time in ms
Session Size
Calculate session size in tokens for LLM API calls. Enter system prompt, turn count, and message lengths to find context window usage and overflow limits.
Log Storage Cost
Calculate log storage cost by daily volume, retention, and compression ratio. Estimate monthly spend for S3, GCS, or any object storage — no sign-up needed.
Freshness Score
Calculate freshness markers for any content type. Enter days since update and half-life to get a 0–100 freshness score and update frequency signal
CRA Score
Calculate your CRA compliance score across 5 cybersecurity domains. Assess EU Cyber Resilience Act readiness for products with digital elements — free, instant
CVE Exposure
CVE exposure calculator that scores vulnerabilities by CVSS, exploit maturity, and asset criticality to help security teams prioritize patch remediation.
Patch SLA
Use the patch SLA calculator to find CVE fix deadlines by severity. Enter discovery date to get due date, days remaining, and SLA breach status instantly
SBOM Coverage
SBOM coverage calculator: score your software bill of materials completeness — track component documentation, metadata quality, and VEX coverage in one place
OTA Compliance
Check OTA compliance rates across your device fleet. Enter fleet size, updated devices, and target to see your compliance gap and time-to-target estimate.
Device Lifecycle
Track device lifecycle compliance across your fleet. Enter EOL device counts and targets to measure your compliance rate and at-risk exposure instantly
Firmware Risk
Calculate firmware risk score for IoT and embedded devices. Enter CVE count, patch age, SBOM coverage, and exposure to get an instant 0–100 risk rating.
Vuln Response Time
Vulnerability response time calculator — enter discovery and remediation dates to check SLA compliance for Critical, High, Medium, and Low severity findings
Encryption Coverage
Calculate encryption coverage across your data assets with this encryption coverage calculator. Measure at-rest and in-transit protection gaps instantly — no sign-up needed.
EU Compliance Quiz
Use this EU device compliance quiz to check whether your IoT or connected device meets Cyber Resilience Act, RED, and CE marking requirements — no sign-up