Straight answers,
workings included.
Free online calculators for the numbers that show up in ordinary decisions — loans, runway, margins, calories, freight, taxes. Type your figures, read the result, see the formula behind it.
No account. No paywall. Your inputs never leave your device.
Why this site exists
Answer a question as simple as "what will this loan actually cost me" and you will usually wade through ten listicles, four lead-generation forms, and zero working. ToolBoost is the opposite kind of site: 135+ calculators built on standard, published formulas, each one free, instant, and honest about the math it uses.
Every calculator on this site starts from the same equation you would find in a finance or physics textbook. Each tool page prints that formula alongside a worked example, so you can verify any result by hand — by pencil and paper, if you like. We deliberately avoid black-box scoring and vague auto-generated "estimates": if a number on this site can't be traced back to an input you typed or a published reference value, it doesn't belong here.
You will also notice what we don't do. No email harvesting before you get an answer. No "premium" version that unlocks a calculation anyone should be able to run for free. No inflating a mortgage tool with ads for that mortgage. The tools are intentionally plain and dependable — the kind you can run standing in a store aisle and still trust an hour later.
Browse by topic
Eight corners of everyday math
Most visitors come in with one question. Pick the neighborhood your question lives in — every category page lists its tools with the formula each one uses.
Finance & Investment
28 toolsLoans, returns, taxes — money decisions with the workings shown.
Business & Operations
22 toolsRunway, margins, and break-even questions for small teams.
Health & Wellness
18 toolsCalories, activity, and lifestyle numbers — estimates, never diagnoses.
Math & Conversion
15 toolsUnits, currencies, and kitchen measures, converted in one line.
Marketing & Growth
16 toolsROI, CPA, CPM, and funnel math for people paying for attention.
Shipping & Logistics
14 toolsLanded cost, freight class, and CBM for importers and sellers.
Home & Living
12 toolsHousehold budgets, deductions, and the occasional grocery mystery.
Gaming & Fun
10 toolsOdds and probabilities, so you can argue from math at the table.
Most used this month
Eight calculators doing the heavy lifting
These are the tools our readers reach for most often. Each row shows exactly what you type in and what you get back — no surprises on the other side of the click.
Investment Return Calculator
Input: principal, rate, term → Output: total return, annualized gain
Compares a lump sum against regular contributions, so you can see which one actually moves the needle over ten years.
Debt Payoff Calculator
Input: balance, APR, monthly payment → Output: payoff date, total interest
Shows the real price tag of a minimum-payment plan — usually a number people prefer not to see, which is the point.
Marketing ROI Calculator
Input: spend, revenue generated → Output: ROI %, cost per acquisition
Answers the question every budget meeting asks: did this campaign pay for itself, and what did each customer cost to win?
Calorie Surplus Calculator
Input: TDEE, intake, activity → Output: surplus/deficit, projected weight change
Turns daily intake into a weekly trajectory, so plans rest on arithmetic instead of forum folklore. Estimates only — not dietetic advice.
Burn Rate Calculator
Input: monthly expenses, cash on hand → Output: runway in months
The number founders check before every hard hiring decision: how many months of salary are still sitting in the account.
Currency Converter
Input: amount, from/to currency → Output: converted amount with live rate
For pricing an overseas supplier invoice or a trip budget, with the reference rate shown so you know what you are being quoted.
Landed Cost Calculator
Input: product cost, shipping, duties → Output: true per-unit cost
The invoice price is never the real price. This adds freight, duty, and fees until you see what one unit truly costs you.
Break-Even Analysis
Input: fixed costs, price, variable cost → Output: break-even units & revenue
How many units before the project stops losing money — the first calculation any honest business plan should contain.
How the tools are built
Three rules every calculator follows
A number is only as trustworthy as the process behind it. This is ours, stated plainly.
Textbook formulas, shown openly
Every tool is specified from a standard published formula — compound interest, contribution margin, Mifflin-St Jeor, NMFC freight tables — not from a guess.
The formula and a fully worked example are printed on each tool page. If you disagree with a result, you should be able to trace exactly which step produced it.
The math stays on your device
Calculations run entirely in your browser. Balances, salaries, body weights, and shipment costs are never sent to our servers, never stored in a database, never attached to an advertising profile.
Close the tab and the numbers are gone. That is a design constraint, not a policy promise.
Reference data with a date stamp
Defaults such as tax brackets, standard deductions, and average rates are reviewed on a published cycle, and every tool page carries a "last reviewed" date.
When in doubt, replace a default with your own figure — your lender's actual APR will always beat any generic example on the internet, including ours.
Quick picks
Twenty tools worth opening right now
A working cross-section of the index — mostly finance and business, with a few everyday conversions mixed in. All free, all instant.
Amortization Schedule
See how each payment splits between interest and principal.
FINAPY Calculator
Compare true yearly yield across compounding schedules.
FINCPM Calculator
Cost per thousand impressions for ad budget planning.
MKTCPC Calculator
What each click really costs across a campaign.
MKTCurrent Ratio
A quick snapshot of short-term business liquidity.
BIZDebt-to-Equity Ratio
Gauge your leverage before borrowing more.
FINDebt Avalanche
Attack the highest-interest debt first; see the time saved.
FINDropshipping Profit
Real margin after product cost, fees, and shipping.
BIZEffective Tax Rate
The percent of income actually paid, not the headline bracket.
FINEPS Calculator
Profit allocated per share, basic and diluted.
FINCustomer LTV
Total value a customer brings before they churn.
MKTContribution Margin
What each sale adds after its variable costs.
BIZCooking Conversion
Cups to grams, ounces to milliliters, oven to oven.
CNVCBM Volume
Cubic meters, for apples-to-apples freight quotes.
LOGFreight Class
NMFC class lookup for LTL shipments.
LOGHome Office Deduction
The simplified square-footage method in three inputs.
FINHoliday Pay
Premium pay for hours worked on public holidays.
FINIncome Tax
A bracket-by-bracket estimate for a filing year.
FINGift Tax
Whether a large gift needs reporting at all.
FINLead Scoring Model
Rank inbound leads by weighted fit signals.
MKTWorked examples
Three calculations, start to finish
Each example below uses the same formulas the linked calculator applies. The inputs are realistic but hypothetical — open the tool to run your own numbers through the identical math. Every line here can be checked by hand.
How long to get out of $28,500 of debt?
The interest line is the argument for overpaying: every extra $100 a month pulls the payoff date in by several months.
Run your own numbers →How many months of runway are left?
Runway counts net burn, not gross — revenue changes the answer more than most founders expect.
Run your own numbers →What is the true cost of that shipment?
A quote that looked fine at invoice price needs a 36% higher retail markup to keep the same margin.
Run your own numbers →Fair questions
Straight answers, again
Are these calculators accurate enough for professional use?
Who writes and reviews the tools?
Do you store any data I enter into the calculators?
Is this financial or medical advice?
Are all the tools really free, or is there a hidden paywall?
How often are the default rates and tax figures updated?
Can I use these tools on my phone or tablet?
Can I suggest a tool or report a wrong result?
A plain-language disclaimer
ToolBoost's calculators, examples, and articles are provided for general informational and estimation purposes only, and do not constitute financial, investment, tax, legal, or medical advice. Illustrative figures on this page (balances, rates, costs) are hypothetical examples used to demonstrate each formula, not recommendations or offers.
Tax rules, benefit thresholds, and freight classifications change over time and differ by jurisdiction — verify against official sources or a licensed professional before acting. Reference data shown on this site was last reviewed in September 2026 and is updated on a rolling cycle.