Founder Cliff Acceleration Calculator

Model your vested shares, cliff status, and accelerated equity in single-trigger and double-trigger acquisition scenarios.

Total shares issued at founding (pre-dilution)
Standard is 12 months — 0 if no cliff
Months since vesting start date
Shares Vested (Standard)
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Vested via time-based schedule
Vested %
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Unvested Shares
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Cliff Status
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Accelerated Shares
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Total at Acquisition
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Months to Full Vest
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What Is Founder Vesting and the Cliff?

Founder vesting is the schedule by which a founder earns their equity over time, rather than owning it all upfront. The industry standard is a 4-year vesting schedule with a 1-year cliff: no equity vests for the first 12 months, then 25% vests on the cliff date, and the remaining 75% vests monthly (1/48 per month) over the next 36 months. The cliff exists to ensure founders are committed before any equity changes hands. According to the National Venture Capital Association's model documents, the 4-year/1-year cliff structure is used in over 90% of VC-backed US startups. Last updated: May 2026.

Single-Trigger vs Double-Trigger Acceleration

Acceleration provisions determine what happens to unvested founder shares at an acquisition. Single-trigger acceleration vests all remaining shares immediately when the acquisition closes — founders get 100% of their equity regardless of whether they stay post-acquisition. Acquirers often resist this because it removes retention incentive. Double-trigger acceleration is more founder-friendly in a balanced way: unvested shares only accelerate if both an acquisition occurs AND the founder is terminated without cause or forced to resign for good reason within a defined window (usually 12 months). Double-trigger is now the market standard recommended by most startup attorneys and VC model documents as a fair compromise between founder protection and acquirer retention needs.

How to Use This Calculator

Enter total founder shares issued at company formation (not options — actual founder stock). Enter the cliff period (12 months is standard; 0 if your agreement has no cliff). Enter months served since your vesting start date — typically the company formation date or your start date as specified in your Founder Stock Purchase Agreement. Select your acceleration type from the dropdown. The calculator shows vested shares under normal time-based vesting, unvested shares remaining, whether you have cleared your cliff, and how many additional shares would accelerate in an acquisition scenario. This output is informational — always have a startup attorney review your specific agreements before any transaction.