A financial calculator is only as good as the answer it gives you. If the number is wrong, a clean design and a fast page don't matter.
That principle guided our latest round of work. Over the past weeks, we rebuilt the calculation engines behind two of our most popular finance tools: the Depreciation Calculator and the Time Value of Money (TVM) Calculator. We checked every method against its official rules, from IRS publications to Spanish and Mexican tax law. We also expanded both tools so they serve businesses well beyond the United States, in English, Spanish and Arabic.
Here is what's new, and why it matters for your numbers.
The Depreciation Calculator: One Tool, Four Standards
Depreciation sounds simple until you ask a basic question: depreciation for what? The figure in your financial statements and the deduction on your tax return are often two different numbers, calculated under two different sets of rules. And tax rules change from one country to the next.
So the calculator now starts with that question.
Choose your depreciation standard first
A new Depreciation Standard selector is the first step. It sets the currency and decides which details the calculator asks for:
- Accounting / Book (IFRS, US GAAP): For financial statements in any country. Choose from straight-line, declining balance, double declining balance, sum-of-years-digits, or units of production.
- US Federal Tax (IRS MACRS): For US federal tax returns, with Section 179 and bonus depreciation estimates.
- Spain – Corporate Tax (LIS): The official table of maximum depreciation rates from Spain's Corporate Income Tax Law, with results in euros.
- Mexico – Income Tax (LISR): The maximum deduction rates from Mexico's Income Tax Law, with results in Mexican pesos.
Once you pick a standard, the form shows only the fields that apply. You won't be asked for a salvage value that the tax law ignores, or for a useful life that the law already fixes.
More accurate book depreciation
We strengthened the accounting methods so that every schedule ends exactly where it should:
- Declining balance now follows standard practice. The rate you enter, such as 150%, is a multiple of the straight-line rate. On a 5-year asset, that means 30% of book value per year. The calculator switches to straight-line when that gives a larger deduction, so the asset is fully depreciated down to its salvage value by the end of its life.
- "Current year" is now really the current year. Enter the date the asset was placed in service, and the calculator shows where today falls in the schedule. It covers this year's depreciation, current book value and accumulated depreciation, including assets not yet in service and those already fully depreciated.
- Clear explanations. A new "How It Was Applied" line shows the rate used, the year of any switch to straight-line, or the depreciation per unit produced.
US tax rules, checked against IRS publications for 2026
For US users, the calculator now reflects the rules in force today, including the changes made by the One Big Beautiful Bill Act:
- Section 179: the 2026 limit of $2,560,000, reduced dollar for dollar once total qualifying purchases exceed $4,090,000 (IRS Rev. Proc. 2025-32). Earlier years use their own published limits.
- Bonus depreciation: 100% for property acquired after January 19, 2025.
- The acquisition date matters. Equipment you agreed to buy in December 2024 but started using in March 2025 qualifies for 40% bonus depreciation, not 100%. That's why the calculator now has an optional Date Acquired field.
- MACRS for buildings: residential rental (27.5-year) and commercial (39-year) property now use the IRS mid-month convention, based on the month the building was placed in service. The calculator also shows that buildings don't qualify for Section 179 or bonus depreciation.
New: Spain and Mexico tax depreciation
This is the update we're most excited about for our Spanish-speaking users.
Spain. Choose from all 33 asset types in the official depreciation table, from machinery (up to 12% a year) to computer hardware (up to 25%) and software (up to 33%). You can:
- Use the maximum rate or any permitted lower rate.
- Choose straight-line or the constant-percentage method.
- Apply the small-company rule (empresa de reducida dimensión), which lets companies with turnover under €10 million depreciate new assets at twice the maximum rate.
- See when the €300 low-value write-off applies.
Mexico. Choose from the asset types and machinery rates by business activity set in the Income Tax Law. The calculator counts only complete months of use in the first year, lets you start deducting the following year, and applies the deductible limit for passenger cars: MXN 175,000, or MXN 250,000 for electric and hybrid cars. On a MXN 400,000 car, it shows that MXN 225,000 is not deductible.
As always, these are estimates for planning. Mexico's inflation adjustment of each deduction is not included, and the calculator says so in its results.
The Time Value of Money Calculator: Precise Answers for Loans and Savings
The TVM calculator solves for any one of five values when you know the other four: the number of periods, the interest rate, the present value, the payment, or the future value. It's the foundation of loan, mortgage, savings and retirement planning, and we made it considerably more dependable.
Reliable interest-rate answers
Finding the interest rate is the hardest TVM calculation, because there is no direct formula. Our new solver finds the rate reliably for realistic loans and savings plans. When no rate can produce your numbers, it tells you so plainly instead of showing a misleading figure.
Payment and compounding frequency, separately
Many loans compound interest on a different schedule from the payments. Canadian mortgages, for example, are paid monthly but compounded semi-annually. The calculator now has separate fields for each.
The difference is real money. On a 400,000 mortgage at 5% over 25 years, the monthly payment is 2,326.42 with semi-annual compounding, versus 2,338.36 if you wrongly assume monthly compounding.
Clearer results
- One simple sign rule: money you receive is positive, money you pay is negative. Every field explains it.
- Results in the right format: a payment shows as money, a rate as a percentage, and a term in years. A details line explains each one, for example "138 full payments plus a smaller final payment".
- Total interest, paid or earned: the summary shows the total interest over the term and whether you paid it (a loan) or earned it (savings).
- A complete balance chart: every period is calculated, so a loan balance falls exactly to zero and a savings balance grows to its target.
Now in Spanish and Arabic
Both calculators, and their step-by-step guides, are now fully available in Spanish and Arabic. That covers every field, option, result and message. Numbers, months and currencies appear in the format readers expect in their language.
- Spanish: Calculadora de depreciación · Calculadora del valor del dinero en el tiempo
- Arabic: Øاسبة الإهلاك · Øاسبة القيمة الزمنية للنقود
Updated Guides, With Real Examples
Each calculator page now includes a detailed guide with worked examples you can reproduce yourself. Examples include a 6.5% mortgage, a savings goal, Spain's machinery depreciation with a mid-year start, and Mexico's car deduction limit. The guides also explain the rules behind every number, so you understand the result as well as see it.
Try the Updated Calculators
Whether you're closing your books, preparing a tax estimate, or comparing a mortgage offer, the updated tools are ready now and free to use:
- Depreciation Calculator: book depreciation, US MACRS with Section 179 and bonus, plus Spain and Mexico tax.
- Time Value of Money Calculator: solve for payment, rate, term, present value or future value.
We'd love to hear which country's tax rules you'd like us to add next.
These calculators provide estimates for planning and education. Tax rules change and depend on your circumstances, so consult a qualified tax professional before filing.