Ryze Labs · Founder Toolkit

Co-founder equity split.

Each founder scores independently, then compare side by side. The gaps between how you each see the contributions are where the real conversation is.

Who are the founders?

The people who will own equity from day one.

Full-time

A few things about your company

These decide how much each factor counts.

How much of the product is built?

What makes this business hard to copy?

Select all that apply

Did anyone take a real risk the others did not?

Answer all three and the tool will explain how it weighted the factors.

Take it with you

A branded one-pager you can hand to a lawyer or cofounder. Your numbers stay in your browser.

A fair starting point

50%

Founder A50%

Founder B50%

Everyone starts here

Every team begins at an even split. Answer step 2 to weight the factors, then split the credit in step 3 to move it off even. (Weighting alone does not change an even split.)

What this tells us

!US founders: file your election within 30 days of your stock grant. There are no extensions, and missing it can cost you a large tax bill later.IRS Section 83(b).

✓Whatever you land on, put every founder on a 4-year with a 1-year .Carta: standard practice.

What vesting actually means

Equity earned over time. 23% of cofounders leave within three years, which is why this protects everyone.

Schedule

with a

cliff

Show the schedule for

Start1-yr cliffYear 4

At the 1-year cliff

12.5%

After year 2

25.0%

After year 3

37.5%

Fully vested (yr 4)

50.0%

Shown on the founding split.

What if a founder leaves?

leaves at month

Founder B walks away with 0%. They leave before the 12-month , so none of their 50% has vested. All of it returns to the company. This is exactly what the cliff is for.

When to redo this

A new cofounder joins
Someone drops to part-time
Before the first raise (the option pool changes everyone’s math)
A major role change

Before you lock anything in: this is a starting point for a conversation, not legal advice. Get a startup lawyer to formalize it (budget $2,000 to $5,000 in United States). Your founders’ agreement should cover:

The equity percentages you settle on
Vesting schedule and cliff for every founder
83(b) elections filed within 30 days of each grant
IP assignment (all founder work belongs to the company)
Acceleration terms (single or double trigger on acquisition)
What happens to equity if someone leaves

Also ask about acceleration: single-trigger vesting speeds up on acquisition, double-trigger on acquisition plus termination. Decide this now, not during a deal.

What to use next

Founders usually check these next

Startup Runway Calculator

Model cash, revenue, burn, and growth across scenarios, and watch your runway and break-even update instantly.

Investor One-Pager

Turn your startup's essentials into a clean, investor-ready one-pager you can share, no slide deck required.

Benchmarks: Wasserman/Harvard Business School (“The Founder’s Dilemmas”); Carta (equal-split trends, vesting norms, SAFE prevalence); YC (Sam Altman on near-equal splits). Tax and legal notes are general information, not advice, and vary by jurisdiction.

Split

Founder A 50%Founder B 50%

Co-founder Equity Split

Founders’ agreement brief

Founder A, Founder B

United States · Delaware C-Corp. Changing how the factors are weighted moves the split by under 2 points, so it is a solid basis for the conversation.

The equity split

Founder A50%

Founder B50%

Vesting

Founder A100% of the 50% stake over 4 years · 12.5% (a quarter) at the 1-year cliff

Founder B100% of the 50% stake over 4 years · 12.5% (a quarter) at the 1-year cliff

Standard: every founder’s own shares vest over 4 years, with a quarter unlocking at the 1-year cliff. 4-year vesting with a 1-year cliff is the US VC standard.

The 83(b) electionFile an 83(b) election with the IRS within 30 days of your restricted stock grant. This is non-negotiable and has no extensions. It lets you pay tax on the near-zero value at grant instead of ordinary income tax as the stock vests and appreciates. Miss it and you could owe tax on stock worth far more later.

Take this to your lawyer ($2,000 to $5,000)

01The equity percentages you settle on

02Vesting schedule and cliff for every founder

0383(b) elections filed within 30 days of each grant

04IP assignment (all founder work belongs to the company)

05Acceleration terms (single or double trigger on acquisition)

06What happens to equity if someone leaves

07Acceleration terms: single vs double trigger

Made with the Ryze Co-founder Equity Split calculator · ryzedesigns.comView online ›

This brief is a starting point for discussion and your lawyer, not legal or tax advice. Figures are the founders’ own inputs.

Who are the founders?

A few things about your company

Get the split right. Then get the brand right.

Startup Runway Calculator

Investor One-Pager

Founder A, Founder B

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