Calculators for people who build and run software
Free, fast, no sign-up. Each tool answers one question and shows its working. Nothing you type leaves your browser.
SaaS Metrics Calculator
MRR, ARR, NRR/GRR, churn, ARPA, LTV, CAC, LTV:CAC, CAC payback and Quick Ratio from one screen of inputs.
FreelanceFreelance Hourly Rate Calculator
Turn a target take-home income into the hourly rate you need to charge — after unpaid time, business expenses and taxes.
Personal FinanceSubscription Cost Calculator
List your recurring subscriptions and see what they really cost per month, per year, and over five years.
Personal FinanceFixed Monthly Expenses Planner
List your rent, bills, insurance and subscriptions to see the monthly and yearly total, a chart by category, and how much of your income is left.
DevOpsUptime / SLA Calculator
Turn an SLA percentage like 99.9% into the exact downtime it allows per day, week, month and year — and work it backwards.
DevOpsCost of Downtime Calculator
Estimate what an outage costs in lost revenue, lost productivity and recovery — as a total and per minute of downtime.
DevOpsError Budget Calculator
From an SLO and a time window, work out the error budget, how much is left, and whether your burn rate will exhaust it early.
DevOpsLatency Percentile Calculator
Paste a list of latency measurements to get p50, p90, p95, p99 and p99.9 — plus how often a multi-request page hits the slow tail.
DevOpsMTBF, MTTR & Availability Calculator
Convert between MTBF, MTTR and availability, get downtime and failures per year, and see how dependencies in series compound.
DevOpsOn-Call Cost Calculator
Estimate what an on-call rotation costs — stipends, incident time, the after-hours interrupt tax — per week, month and year.
Personal FinanceInflation Calculator
See what a US dollar amount from one year is worth in another, with cumulative and average annual inflation.
Personal FinanceSavings Goal Calculator
Work out how much to save each month to hit a goal by a date — or how long a fixed monthly amount will take.
FreelanceHourly to Salary Calculator
Convert an hourly rate to yearly, monthly and weekly pay, and back again — with your own hours and weeks.
Personal FinanceCompound Interest Calculator
Project savings or investments over time with a starting amount, regular contributions and compounding — with a year-by-year breakdown.
DevOpsLLM API Cost Calculator
Estimate what an LLM feature costs per request, per day and per month from token volume and per-model pricing.
More tools coming
This site is being built out one calculator at a time — freelance rate, cloud cost comparison, LLM API cost, crypto staking and others are on the way.