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Solo 401(k) Contribution Calculator

Estimate employee and employer solo 401(k) contribution limits for owner-only businesses.

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Solo 401(k) for Self-Employed Individuals

A Solo 401(k), also called an Individual 401(k) or one-participant 401(k), is the most powerful retirement savings vehicle available to self-employed individuals with no employees (other than a spouse). It combines employee elective deferrals with employer profit-sharing contributions to allow significantly higher total contributions than a SEP IRA or traditional IRA.

The Two-Part Contribution Structure

Unlike a SEP IRA (which only allows employer contributions), a Solo 401(k) lets you contribute in two capacities. As the employee, you can defer up to $24,500, plus an $8,000 catch-up if age 50-59 or 64+ or an $11,250 catch-up if age 60-63, of your earned income. As the employer, you can add up to 25% of your net self-employment income after the SE tax deduction, which works out to an effective 20% rate for self-employed calculations. These two contributions stack, often allowing you to shelter $40,000-$72,000 or more per year, with higher totals when catch-up contributions apply.

When the Solo 401(k) Beats the SEP IRA

The Solo 401(k) advantage is most dramatic at lower income levels. If you earn $60,000, a SEP IRA limits you to about $11,000 (20% of adjusted net earnings). A Solo 401(k) allows $24,500 in employee deferrals plus $11,000 in employer contributions, totaling about $35,500 -- more than triple the SEP. At higher incomes, the two plans move closer to the same annual additions cap.

Roth Solo 401(k) Option

Many Solo 401(k) providers offer a Roth option for the employee deferral portion. This lets you make after-tax contributions that grow and are withdrawn completely tax-free in retirement. SEP IRAs do not offer a Roth option at all. This makes the Solo 401(k) uniquely flexible for tax planning.

Important Deadlines and Rules

The plan must be established by December 31 of the tax year (unlike a SEP IRA)
Employee deferrals are due by December 31; employer contributions can be made until the tax filing deadline
If plan assets exceed $250,000, you must file Form 5500-EZ annually
You cannot have the plan if you have full-time W-2 employees (spouses excepted)
You can take a loan from your Solo 401(k) (up to $50,000 or 50% of the balance)

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How to Use the Solo 401(k) Contribution Calculator

1
Enter your values
Open the Solo 401(k) Contribution Calculator and fill in the required input fields with your numbers or selections.
2
Review the calculation
The tool automatically computes the result as you type. Double-check your inputs to ensure accuracy.
3
Interpret your results
Review the calculated output along with any breakdowns, charts, or explanations provided to understand what the numbers mean for your situation.

Frequently Asked Questions

What is the Solo 401(k) Contribution Calculator?

The Solo 401(k) Contribution Calculator is a free browser-based tool on ConvertCrunch. Estimate employee and employer solo 401(k) contribution limits for owner-only businesses. It requires no downloads, installations, or account signups. Simply enter your values and get instant, accurate results. The tool is designed for quick calculations and informed decision-making, whether you are a professional, student, or everyday user looking for reliable answers.

How do I use the Solo 401(k) Contribution Calculator?

Using the Solo 401(k) Contribution Calculator is straightforward. Enter your values into the input fields provided on the page, then calculate or adjust parameters to explore scenarios. Most processing happens locally in your browser. If a feature uses a third-party service, the tool identifies that connection and the privacy policy explains it. Most users get the answers they need in under a minute.

Is the Solo 401(k) Contribution Calculator free to use?

Yes, the Solo 401(k) Contribution Calculator is completely free to use with no account signup, email requirement, or premium tier. Most calculations run locally in your browser. Features that depend on live data or a third-party service require a network connection and are identified in the tool. You can use it as many times as you need for personal, educational, or professional purposes.

How accurate is the Solo 401(k) Contribution Calculator?

The Solo 401(k) Contribution Calculator uses common industry formulas and benchmarks for freelance business planning. Results are based on the inputs you provide and standard assumptions about business expenses and utilization rates. Actual outcomes depend on your market, specialization, geographic location, and negotiation skills. Use results as a baseline and adjust based on your direct experience and local market conditions.

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Solo 401(k) for Self-Employed Individuals

The Two-Part Contribution Structure

When the Solo 401(k) Beats the SEP IRA

Roth Solo 401(k) Option

Important Deadlines and Rules

The plan must be established by December 31 of the tax year (unlike a SEP IRA)
Employee deferrals are due by December 31; employer contributions can be made until the tax filing deadline
If plan assets exceed $250,000, you must file Form 5500-EZ annually
You cannot have the plan if you have full-time W-2 employees (spouses excepted)
You can take a loan from your Solo 401(k) (up to $50,000 or 50% of the balance)