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Late fee calculator
The late fee calculator is a free tool that estimates the late fee on an overdue invoice in seconds. Enter the amount, your rate (monthly, annual, or flat), and how many days past due it is, and it shows the fee, the daily accrual, and the new total due. It runs entirely in your browser and saves nothing. Then send invoices with clear terms in PayNugget so you rarely have to charge one.
Late fee
$15.00
- Original invoice
- $1,000.00
- Late fee
- $15.00
- Accruing per day
- $0.50
- Total now due
- $1,015.00
Estimate only. Late fees and maximum interest rates are regulated by state law — confirm what's allowed where you operate and state the rate in your invoice terms before charging it.
Stop calculating late fees by hand.
Send invoices with clear terms and automatic reminders in PayNugget — so they get paid before a late fee is ever needed.
Free to start · low-cost ACH · you own your data
Fair, not punitive
Charge fairly — and try not to need to
A stated late fee protects your cash flow. The real goal, though, is to get paid before one is ever due.
- Typical monthly rate
- 1–1.5%
- Accrual, shown as it adds up
- Daily
- Runs in your browser only
- Private
- Beats Net 30 for getting paid
- Net 14
How it works
Estimate a late fee, then prevent the next one
Calculate what's owed today — and set up invoices so it doesn't happen again.
Enter the invoice details
Add the original amount, choose a monthly, annual, or flat-fee basis, and your rate.
11Set days past due
Tell the calculator how overdue the invoice is. The fee and daily accrual update instantly.
22Invoice with clear terms
In PayNugget, state your late-fee terms up front and let automatic reminders prevent overdue invoices.
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Late fees, done right
Charge fairly — and try not to need to
A late fee is a legitimate tool for protecting your cash flow, but it only works when it's set up correctly. State the rate in your invoice terms before the work starts, keep it within the limits your state allows, and apply it consistently. A surprise fee damages the relationship; an agreed-upon one signals that you run a serious business.
That said, the goal isn't to collect late fees — it's to get paid on time. The most reliable way to avoid overdue invoices is to remove friction and forgetting: send the invoice immediately, make paying a two-click ACH transfer, keep terms short, and let automatic reminders do the chasing. See more tactics in our guide to getting paid faster.
Ready to send a real invoice? Use the free invoice generator to build one, or browse invoice templates by trade.
The best late fee is the one you never have to charge.
Keep exploring
Related tools, guides & features
Model the fee here, then set up invoices so you rarely have to charge one.
Get paid faster
The reliable way to avoid late fees entirely — remove the friction and the forgetting.
Free invoice generator
Build a professional invoice in your browser with live subtotal, tax, and total.
Low-cost ACH payments
Let clients pay from their bank in two clicks for about $4 on a $1,000 invoice.
Invoice templates
Pick a format with clear terms baked in so your late-fee policy is stated up front.
Late fees: frequently asked questions
How fees are calculated, what's reasonable, and how to avoid them.
- How do you calculate a late fee on an invoice?
- For a percentage-based fee, convert the stated rate to a daily rate and multiply by the invoice amount and the number of days overdue. For example, a 1.5% monthly rate is about 0.05% per day; on a $1,000 invoice that's roughly $0.50 per day, or about $15 after 30 days. A flat late fee is simply a fixed dollar amount added once the invoice is past due.
- What is a reasonable late fee to charge?
- A common approach is 1% to 1.5% per month (12% to 18% per year) on the overdue balance, or a modest flat fee for smaller invoices. Whatever you choose, state it clearly in your invoice terms before the work begins so it never comes as a surprise.
- Are late fees legal?
- Late fees are generally allowed when they're agreed to in advance and within the limits your state sets. Many states cap the maximum interest rate you can charge on overdue invoices, so confirm the rules where you operate and put the rate in your written terms. This calculator gives an estimate, not legal advice.
- Should I use a monthly rate, an annual rate, or a flat fee?
- A monthly percentage (like 1.5% per month) is the most common for B2B invoices. An annual rate (APR) is the same idea expressed yearly. A flat fee is simplest for small or one-off invoices. This tool supports all three so you can compare.
- How can I avoid charging late fees at all?
- The best late fee is the one you never have to charge. Invoice the moment work is done, offer an easy online payment option like low-cost ACH, set clear short terms, and turn on automatic reminders. PayNugget does all of this so most invoices get paid before a fee is needed.
- Does this calculator save my numbers?
- No. The calculator runs entirely in your browser — nothing is stored or sent anywhere. To send invoices that state your late-fee terms and remind clients automatically, create them in PayNugget.
Invoice with clear terms — and get paid on time
Send invoices with stated late-fee terms and automatic reminders in PayNugget. Free to start, no subscription.