Tools built for
technical operators
Free calculators for AI builders, startup founders, and SaaS teams. No sign-up. No paywalls. Runs in your browser.
AI & LLM Economics
AI Token Calculator
Estimate token usage and API billing for GPT, Claude, Gemini, and DeepSeek. Compare costs across models in real time.
Context Window Estimator
Break down prompt payload — system prompt, history, RAG chunks, and output — to measure remaining context capacity.
LLMs.txt Generator
Generate an AI-ready llms.txt file for any website in seconds.
Embedding Cost Calculator
Calculate the cost of embedding your documents for RAG or semantic search, and compare rates across providers.
Fine-Tuning Cost Calculator
Estimate the one-time training cost of fine-tuning an LLM on your own dataset.
Vector Database Cost Calculator
Estimate the monthly cost of storing and querying your vectors across Pinecone, Weaviate, and Qdrant.
SaaS & Business Operations
SaaS Unit Economics
Calculate LTV, CAC, payback period, and gross margin health. Model churn impact on revenue and valuation.
MRR & ARR Calculator
Model net new MRR, ARR, NRR, and MoM growth. Break down new, expansion, contraction, and churned revenue.
Burn Rate & Runway
Model gross and net burn, funding runway, and exhaustion date. Project monthly cash flow with dynamic inputs.
S Corp Tax Savings
Calculate tax savings from electing S Corporation status in 2026. Compare W-2 salary, QBI deductions, and state corp fees.
Work Hours Calculator
Calculate work hours with lunch break deduction, decimal hours, and weekly or monthly projections.
Weighted Overtime
Calculate blended regular rates and FLSA-compliant overtime pay for employees working multiple hourly rates.
Bonus Tax Calculator
Estimate net take-home pay on your employer bonus check using 2026 supplemental tax rates and FICA limits.
France VAT Refund
Calculate estimated tourist tax refunds (détaxe) on purchases in France. Compare cash, credit card, and digital app payout rates.
VAT Calculator Ireland
Calculate Irish Value-Added Tax (VAT) for retail and services. Add or remove VAT, updated with 2026 Revenue schedules.
Review Intelligence Analyzer
Detect review manipulation through language authenticity scoring, rating distribution patterns, and velocity anomaly detection.
General Calculators & Converters
Square Footage Calculator
Calculate area for rectangles, triangles, circles, and irregular L-shaped rooms.
Percentage Increase Calculator
Calculate percentage increase, decrease, and absolute change between two values.
Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin with body temperature and cooking reference charts.
Tip Calculator
Calculate tip amount, total bill, and per-person cost with split bill support.
Age Calculator
Calculate exact age in years, months, and days from a date of birth, with fun facts.
Days Between Dates
Calculate total days, business days, and a month-by-month breakdown between two dates.
Time Zone Converter
Convert a date and time between 13 major world time zones, with daylight saving time handled correctly.
Time Duration Calculator
Calculate the exact duration between two clock times, in hours, minutes, and decimal hours.
Timesheet Calculator
Enter real clock-in and clock-out times for each day of the week and get your actual weekly total.
Overtime Calculator
Calculate overtime pay at a single hourly rate — regular pay, overtime pay, and total gross pay.
PTO Calculator
Calculate your accrued PTO balance from your annual allotment, pay period frequency, and days used.
Countdown Calculator
Count down to any date and time in days, hours, minutes, and seconds — updating live.
Meeting Time Finder
Find overlapping working hours across up to 3 time zones to schedule a meeting everyone can attend.
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and back, with automatic unit detection.
GPA Calculator
Calculate your GPA on a 4.0 scale from letter or percentage grades and credit hours.
BMI Calculator
Calculate body mass index, category, and healthy weight range with metric and imperial units.
Decimal to Fraction
Convert decimals to simplified fractions and mixed numbers, with reverse fraction-to-decimal mode.
Latest Guides
AI API Token Costs Explained: How GPT, Claude & Gemini Pricing Actually Works
A practical breakdown of how LLM API pricing works, what actually drives your bill up, and how to estimate and cut costs across GPT, Claude, Gemini, and DeepSeek.
LLM Context Windows Explained: How Much Can You Actually Fit in a Prompt?
What a context window really measures, how system prompts, chat history, and RAG chunks eat into it, and how to avoid silent truncation and overflow errors.
Why Utilitymania?
Every tool runs entirely in-browser. Results are immediate, private, and copyable. Built for repeat daily use by founders and builders who need correct numbers without friction.
No sign-up
Open and use instantly
Server-rendered
Fast initial loads
Mobile-ready
Works on any device
No paywalls
All tools are free