How These Calculators Work
Every number on this site is an estimate produced by standard formulas. Here is exactly what they do, and exactly what they leave out.
Loan payments
Monthly payments use the standard amortisation formula:
payment = P × r × (1 + r)^n / ((1 + r)^n − 1)
where P is the amount financed after any down payment, r is the monthly rate (annual rate ÷ 12), and n is the term in months. This is the same formula a lender uses for a simple-interest instalment loan.
Lease payments
Leases use a money-factor approximation: monthly depreciation (cost − residual) ÷ term plus a finance charge (cost + residual) × r ÷ 2. Real lease pricing varies by structure, a $1 buyout, a 10% PUT and a fair-market-value lease all price differently, so treat lease output as directional rather than precise.
What is excluded, and it matters
Our estimates do not include:
- Documentation, origination or administration fees
- Sales tax
- Insurance
- UCC filing costs
- Delivery, installation or commissioning
- Any deposit or advance payment the lender requires at signing
On a real deal these can add meaningfully to the total. A quote will always be higher than our estimate, sometimes by several percent.
Where the rate ranges come from
The default rate ranges shown on each calculator are illustrative starting values we set per equipment category so the tool opens with something plausible. They are not a rate survey, not a quote, and not sourced from any lender's rate card. Change them to whatever you have actually been offered, that is what the input is for.
Tax calculators
Our Section 179 tools use published 2026 figures: a $2,560,000 deduction limit, a spending phase-out beginning at $4,090,000, and a $32,000 cap for vehicles between 6,000 and 14,000 lb GVWR. We apply the 50% business-use test and, where you supply it, the taxable-income limitation.
They still simplify. They do not handle short tax years, related-party rules, state conformity, listed-property recapture, or the interaction with bonus depreciation in every case. Nothing on this site is tax advice. Confirm your position with a CPA or enrolled agent before you file. Primary sources: IRS Publication 946 and Form 4562.
Nothing you type is sent anywhere
Every calculator runs in your browser. No input is transmitted, stored or logged by us. You can check this yourself by opening your browser's network tab while you use one.
Found something wrong?
Tell us and we will fix it. Corrections to the maths or the tax figures are welcome and we would rather be corrected than confidently wrong. See the contact page.
Last updated 29 July 2026.