If you're building a startup, the number that should keep you up at night isn't your valuation — it's your runway. How many months of cash do you have left? Can you survive a bad quarter? Should you raise now or wait six months?
The good news: math is free, and it runs in your browser. These 10 tools help founders, indie hackers, and finance teams model cash flow, run scenarios, and make sharper decisions — no logins, no installs, no subscription required.
Why Runway Is the Only Number That Matters Early
Revenue means nothing if you run out of cash before it arrives. Most startups don't die because the idea failed — they die because the timing did. The Startup Runway Calculator gives you the only number that actually counts: months of operating time given your current cash, monthly burn, and revenue growth. Plug in your numbers and you'll get a runway date, a break-even point, and the amount you need to raise for 12 or 18 more months of operating time. Use it monthly, or weekly if you're nervous.
The 10 Tools Every Founder Should Bookmark
1. Startup Runway Calculator
The only calculator built specifically for the founder question: "When do I run out of money?" Enter cash on hand, monthly burn, and expected revenue growth, and it returns months of runway, the date you'll hit zero, and the target raise size. No more "we have enough to hire two more engineers" without knowing the math behind it.
2. Freelance Rate Calculator
Whether you're a solo founder or hiring contractors, the Freelance Rate Calculator tells you the true hourly rate you need to charge to hit your target income after taxes and overhead. It's the same logic in reverse: if you want to net $120K, what do you actually need to bill — and how many billable hours does that require to stay sane?
3. Credit Card Payoff
Debt kills runway. The Credit Card Payoff tool shows exactly how many months until you're debt-free and how much interest you'll pay along the way. If you're funding your startup on a credit card (please don't — but if you are), this tells you when the damage ends and how aggressive your paydown needs to be.
4. SIP Calculator
For founders in markets with strong mutual fund ecosystems, the SIP Calculator projects returns on systematic monthly investments. Use it to model personal savings, founder reserves, or a small angel allocation while you build.
5. Lumpsum Calculator
Got a windfall, a SAFE payout, or a small raise? The Lumpsum Calculator projects the future value of a one-time investment over 1, 5, 10, or 30 years. It's a quick way to compare "deploy $200K into the business" vs. "keep it liquid for runway."
6. ROI Calculator
Every marketing channel, hire, and feature has a return. The ROI Calculator gives you percentage return and annualized gain in seconds. Run it before committing to an ad campaign, a new tool, or that next contractor you're considering.
7. Income Tax Calculator
Founders often forget: equity isn't income until you sell it, and a $200K salary doesn't mean $200K in the bank. The Income Tax Calculator breaks down federal brackets, deductions, and net take-home so you can plan your draw, not just your burn.
8. Net Worth Calculator
Runway is one side of the balance sheet. The Net Worth Calculator tracks total assets minus liabilities — your house, your stock, your savings, your debts. Founders who know their personal runway make calmer decisions about salary, equity, and risk.
9. Content Brief Generator
Fundraising, content marketing, and SEO all depend on shipping words that rank. The Content Brief Generator creates lightweight briefs with title ideas, outlines, and FAQ prompts from a target keyword. Five minutes of structure saves hours of staring at a blank doc — and the briefs it produces actually rank.
10. Open Graph Preview
When you ship a launch, send a fundraising update, or post a milestone, the link preview matters. The Open Graph Preview tool shows exactly how your page renders on Twitter, LinkedIn, and Slack before you hit publish. A 30-second check that prevents embarrassing blank-image shares.
How to Use These Tools Together
Don't treat each tool as a one-off. The founders who run tight ships run them in cycles: every Friday they check runway. Every month they re-run ROI on their top three spend categories. Every quarter they revisit tax planning and net worth. Stack these into a 15-minute weekly review and you'll outpace 90% of startups still arguing in spreadsheets.
FAQ
How accurate is a startup runway calculator?
As accurate as the inputs you give it. Real burn fluctuates month to month, and growth rarely follows a clean line. Use the calculator for directional planning — "I have 14 months, not 6" — and then stress-test with a 20% downside scenario before you commit to a hire or a launch.
What's a healthy runway for an early-stage startup?
Most VCs want to see 12–18 months of runway post-raise. Pre-revenue, anything under 6 months is danger territory; under 3 months is a fundraising emergency. The longer your runway, the more optionality you have on price, terms, and timing.
Should I include founder salaries in burn?
Yes, always. Founders often forget their own draw when modeling burn. If you're paying yourself $5K a month and have $200K in the bank, your real burn includes that $5K — and your real runway is shorter than the headline number suggests.
The Bottom Line
Runway is a function of three things: cash, burn, and growth. You can model all three for free. Open the Startup Runway Calculator, run your numbers, and bookmark the rest of this list for the next time you need to make a sharp financial call. The founders who survive aren't the ones with the best ideas — they're the ones who plan.