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ToolSelf Blog

Guides on taxes, finance, business, and practical tools for freelancers and everyone.

Finance

Business Loan Calculator: Is the Interest Worth It?

Taking out a business loan? Calculate the total cost of interest and decide if it makes sense for your business.

Feb 18, 2026
Finance

Retirement Planning for Freelancers: SEP-IRA vs Solo 401k

As a freelancer, you have more retirement options than a W2 employee. SEP-IRA and Solo 401k allow you to save more and reduce taxes.

Feb 18, 2026
Finance

Emergency Fund: How Much Should Freelancers Save?

Income varies as a freelancer. Here's how much emergency savings you should have and where to keep it.

Feb 17, 2026
Business

Invoice Late Fees: How Much Can You Charge?

Late fees encourage clients to pay on time. But there are legal limits. Here's what you can charge in each US state.

Feb 15, 2026
Taxes

Income Tax Refund Estimator: Will You Get Money Back?

Freelancers rarely get refunds because they don't have withholding. But if you had other W2 income, you might. Here's how to estimate.

Feb 15, 2026
Business

ROI Calculator: Measure Your Marketing Spend

Track the return on your marketing investments. Simple formula: (revenue gained - cost) / cost × 100.

Feb 9, 2026
Taxes

Business Expenses: What Counts as a Deductible Write-Off

Not all expenses are deductible. The IRS has specific rules. Here's what counts and what doesn't.

Feb 9, 2026
Date & Time

Unix Timestamps Explained: Why Computers Count Seconds

Computers represent time as seconds since 1970-01-01 UTC. Knowing why helps you debug timezone issues for life.

Feb 9, 2026
Image

Image Compression Without Visible Quality Loss

JPEG quality 75-85 is the sweet spot. Lossless PNG optimization can shrink files 20-50% with zero quality change.

Feb 8, 2026
Date & Time

Pomodoro Technique: 25/5 vs 50/10, Which Works Better?

The traditional 25-minute pomodoro is one option. Research suggests 52/17 or 90-minute ultradian rhythms work too.

Feb 4, 2026
Business

Insurance for Freelancers: What Do You Actually Need?

Errors and omissions insurance protects you if you make a mistake that costs a client money. Is it worth it?

Feb 2, 2026
Taxes

Mileage Deduction: Track Miles, Save on Taxes

Business miles are deductible at the IRS standard rate. Here's what counts as business mileage and how to track it properly.

Feb 1, 2026