100+ Free Online Calculators
for everything you calculate.

Calculate your monthly mortgage payment, total interest, and full amortization schedule for any home loan.

Estimate monthly payments and total interest for any fixed-rate loan.

See how investments grow over time with compound interest and regular contributions.

Estimate whether you're on track to retire — see your nest egg at retirement age.

Calculate return on investment as a percentage.

Calculate sale price after applying a discount percentage.

Calculate Customer Acquisition Cost from marketing and sales spend.

Calculate Customer Lifetime Value.

Body Mass Index — weight-to-height ratio.

Basal Metabolic Rate — calories burned at rest.

Total Daily Energy Expenditure.

Calculate percentages, percentage of, and percentage change.

Full-featured scientific calculator with trig, logs, powers.

Exact age from birth date.

Format, validate and beautify JSON.

Encode text to Base64 and decode back.

Generate v4 UUIDs.

Convert Unix timestamp to date and vice versa.

Generate a QR code for any text or URL.

Generate strong random passwords.

Estimate monthly AI API costs across OpenAI, Anthropic, Google and open models by tokens and request volume.

Calculate OpenAI API spend for GPT-4o, GPT-4o mini, GPT-4 Turbo, o1 and GPT-3.5 by tokens and request volume.

Convert token counts and per-million-token prices into dollar cost per request, per day and per month.

Estimate ChatGPT API costs for building a chatbot — includes conversation history, system prompts and monthly volume.

Estimate monthly GitHub Actions spend by runner OS, workflow minutes, jobs and included free tier.

Calculate monthly API spend by requests, cost per 1,000 calls, data transfer and free tier.

Compare monthly cloud VM costs across AWS, Azure and GCP with storage, egress and reserved-instance discounts.

Quantify the revenue, wage and SLA cost of outages by minutes down, revenue rate and affected staff.

Find your true freelance hourly and day rate from target salary, expenses, taxes and billable hours.

See the true monthly, yearly and 5-year cost of a SaaS or subscription — with seats, price hikes and trial periods.

Estimate total project cost from labor hours, materials, overhead, contingency and profit margin.

Convert salary and target income to hourly, daily, weekly and monthly rates — with taxes and PTO.

Estimate the USD cost of any Ethereum transaction from gas price (gwei), gas limit and ETH price.

Project staking income across ETH, SOL, ADA and other proof-of-stake assets using APR, compounding and price change.

See what a dollar-cost averaging plan would have returned — enter buy size, frequency and start date.

Calculate profit, fees and ROI on a crypto trade from buy price, sell price and position size.

Compute blended and paid CAC from marketing spend, sales headcount cost and new customers acquired.

Estimate customer lifetime value from ARPA, gross margin and monthly churn, with LTV:CAC comparison.

Convert between MRR and ARR, project growth, and see quick-ratio and net new MRR from movement inputs.

Compute customer and revenue churn, retention rate, and average customer lifetime from monthly numbers.

Estimate YouTube ad revenue from views, CPM, RPM and niche — plus sponsorship-equivalent income.

Model the return on an SEO investment from traffic, conversion rate, order value and content cost.

Calculate email campaign revenue and ROI from list size, deliverability, open rate, CTR and conversion.

Convert word count into reading time for any audience — supports fast, average and technical reading speeds.