100 free calculators for
building, selling and everyday math

Estimate materials, marketplace fees, ad costs, energy use and more. Every calculator shows its formula and a worked example, with US units and dollars as the defaults.

Construction, Home & GardenRoofing, Concrete & MasonryAuto, Fuel & TravelBusiness, Pricing & PaymentsMarketplace & Seller FeesMarketing & AdvertisingElectrical, Solar & EnergyPets, Maker & Everyday Math

Construction, Home & Garden

Materials, areas and volumes for building, landscaping and home projects.

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Cubic Yard CalculatorConvert length, width and depth into cubic yards.Square Footage CalculatorFind the area of rooms, lots and yards in square feet.Gravel CalculatorEstimate cubic yards and tons of gravel for an area.Topsoil CalculatorWork out cubic yards, tons and bags of topsoil.Mulch CalculatorEstimate mulch volume and bags for a garden bed.Paint CalculatorEstimate gallons of paint from walls, openings and coats.Flooring CalculatorEstimate flooring and boxes for a room, with waste.Tile CalculatorEstimate tiles and boxes for a floor or wall.

Roofing, Concrete & Masonry

Roof geometry, concrete, block, brick and rebar quantities.

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Roof Pitch CalculatorGet pitch, angle, slope and rafter length.Concrete Slab CalculatorEstimate cubic yards and bags for a slab.Rafter Length CalculatorFind rafter length from span, pitch and overhang.Roofing / Shingle CalculatorEstimate roof area and shingle bundles.Concrete Footing CalculatorEstimate concrete for strip and pier footings.Brick CalculatorCount bricks and mortar for a wall.Rebar CalculatorCount rebar pieces and total length for a slab.Concrete Block CalculatorCount concrete blocks for a wall.

Auto, Fuel & Travel

Fuel economy, trip costs, depreciation and mileage figures.

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Tire Size CalculatorFind overall tire diameter from width, aspect ratio and rim size.Gas / Fuel Trip Cost CalculatorEstimate fuel cost for a trip from distance and price.MPG CalculatorCalculate miles per gallon from miles and fuel used.Car Depreciation CalculatorEstimate a car’s value over the years.EV vs Gas Cost CalculatorCompare yearly fuel costs of an EV and a gas car.Mileage Reimbursement CalculatorMultiply business miles by a cents-per-mile rate.

Business, Pricing & Payments

Pricing, pay, commission and break-even maths for work and small business.

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Markup vs Margin CalculatorConvert between markup and margin and find the price.Break-Even Point CalculatorFind units and sales needed to cover your costs.Overtime CalculatorWork out overtime pay from rate, hours and multiplier.Salary to Hourly CalculatorTurn an annual salary into an hourly rate.Sales Commission CalculatorCalculate commission with quotas and tiered rates.Freelance Rate CalculatorFind an hourly rate from income goals and expenses.Price Per Unit CalculatorCompare unit prices across two or three options.Landed Cost CalculatorAdd freight, duty and fees to find cost per unit.

Marketplace & Seller Fees

Fees, payouts and profit for online marketplaces and payment processors.

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eBay Fee CalculatorEstimate fees, payout and profit for an eBay sale.Etsy Fee CalculatorAdd up Etsy listing, transaction and processing fees.PayPal Fee CalculatorEstimate PayPal fees and the amount you receive.Stripe Fee CalculatorEstimate Stripe card fees and your net payout.Shopify Fee CalculatorEstimate Shopify plan and card fees on your orders.Amazon FBA Fee CalculatorEstimate Amazon FBA fees, payout and profit.Poshmark Fee CalculatorEstimate Poshmark fees, payout and profit.Reseller Profit CalculatorFind profit and margin on items you resell.

Marketing & Advertising

Ad return, acquisition cost, click rates and budget planning.

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Break-Even ROAS CalculatorFind the ad return you need to break even.Customer Acquisition Cost (CAC) CalculatorDivide marketing spend by customers won.Customer Lifetime Value (CLV) CalculatorEstimate the revenue a customer brings over time.CTR CalculatorCalculate click-through rate from clicks and impressions.CPM CalculatorCalculate cost per thousand impressions.Cost Per Lead CalculatorDivide ad spend by leads generated.Affiliate Commission CalculatorEstimate affiliate earnings from sales and rates.Ad Budget CalculatorEstimate how much ad spend a goal could need.

Electrical, Solar & Energy

Power, wiring, battery, solar and energy cost estimates.

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Solar Panel Cost CalculatorEstimate panels, cost and yearly output.Solar Payback CalculatorEstimate savings and payback time for solar.Solar System Size CalculatorEstimate system size from your electricity use.Electricity Cost CalculatorEstimate what an appliance costs to run.EV Charging Cost CalculatorEstimate the cost of charging an electric car.Watts to Amps CalculatorConvert watts to amps for a given voltage.Wire Size CalculatorEstimate wire gauge for a circuit.BTU (AC Sizing) CalculatorEstimate the BTUs needed to cool a room.

Pets, Maker & Everyday Math

Pet age and feeding, craft and print costs, and everyday percentages.

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Dog Age CalculatorConvert dog years to human years by size.3D Printing Cost CalculatorFind the true cost of a 3D print and a suggested price.Cat Age CalculatorConvert cat years to human years.Dog Food CalculatorEstimate how much food your dog needs each day.Discount CalculatorFind a sale price and the amount saved.Aquarium Volume CalculatorFind the gallons in an aquarium.Craft Pricing CalculatorPrice handmade items from materials, time and overhead.Candle Wax CalculatorEstimate the wax needed for candle containers.

Clear, private and easy to trust

Open a calculator, enter your numbers and read the result. Here is what to expect from every page.

No account needed

There is no sign-up, login or payment step. Pick a calculator and start.

Inputs stay in your browser

Results are worked out on your device. The numbers you type are not sent to our server.

Formulas shown

Each page explains how the result is calculated in plain words, then walks through a worked example.

Assumptions stated

Pages list what a result assumes and where real quotes can differ, so you know how far to rely on it.

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Works on the screen you already have

Pages reflow to fit your screen. Inputs and buttons keep a comfortable tap size, and the result appears right under the form.

Phones

A single-column layout with full-width inputs, so forms are easy to fill in one-handed.

Tablets

Two-column card grids and line lengths that stay comfortable to read.

Desktop screens

Wider grids, four calculators per row and a category menu in the header.

Why use Zayvora Calculators

Every calculator is built so you can see, change and check the numbers behind the answer.

100 calculators, 8 categories

Building materials, seller fees, ad metrics, energy, pets and more, grouped so you can browse or search.

Formulas in plain words

No black boxes. You can follow the maths and repeat it by hand.

Worked examples

Real numbers taken step by step, so you can compare your result with a known one.

Editable rates and defaults

Fees, prices and percentages are input boxes with starting values you can replace with your own.

Guides that go deeper

Blog articles explain the maths behind selected calculators, with examples.

US units and dollars

Feet, inches, gallons and USD are the defaults, because this site is written for US readers.

Results are estimates for information only. They are not financial, tax, legal, engineering or other professional advice. See the Disclaimer.

Latest guides

Practical explainers that go with the calculators.

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Frequently asked questions

How do I use a calculator?

Pick a calculator, type your numbers and press Calculate or Enter. Rates and defaults are editable boxes. Every page explains its formula and shows a worked example, so you can check any result by hand.

Are the calculators free, and do I need an account?

They are free. There is no sign-up, no download and no account.

How accurate are the results?

Results are estimates worked out from the formulas and the numbers you enter. Display rounding is applied only at the end. Real costs also depend on things a simple tool cannot see, such as category, account type, ground conditions or local rules.

Do you store or send the numbers I type?

No. Calculations run in your browser, and the numbers you type into a calculator are not sent to our server. Read the Privacy Policy for what the site does collect.

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