Free Calculators, Grouped by What You're Working On
Thirty calculators and converters for home projects, seller fees, pools, gaming, work hours and more. No accounts, no tracking, nothing to install.
What every page here does
The formula, stated. Each calculator puts its formula in plain words above the tool, then works one real example with numbers you can check on paper.
Sources, dated. Every page that quotes a fee, rate or material figure lists where it came from and when it was last reviewed — and every number is editable on the page.
Home & yard
- deck material calculator
Boards, screws or clips, and cost from your deck size, board width and waste factor.
- gravel calculator
Cubic yards, tons and cost from area and depth, by stone type.
- mulch calculator
Cubic yards, bag count, and bag-versus-bulk cost for any bed.
- concrete bag calculator
How many 80, 60 or 40 lb bags for a slab or post holes.
- raised bed soil calculator
Soil volume, bag count and a mix-recipe splitter for garden beds.
- tile calculator
Tile and box counts with waste percent and cost per box.
- drywall calculator
Sheets plus mud, tape and screws for any room, doors and windows deducted.
- fence calculator
Pickets, posts, rails and post-hole concrete for a whole run.
- paint calculator
Gallons per coat with doors and windows deducted from the wall area.
- roof shingle calculator
True roof area from pitch, in squares and bundles, waste included.
- paver calculator
Paver count by size plus polymeric sand bags and gravel base.
Fees & seller money
- stripe fee calculator
Fee and net on any charge, or the charge that nets a target amount. US and Canada rates.
- paypal fee calculator
Goods & Services fee and net both directions, card-funded and international.
- etsy fee calculator
Listing, transaction, processing and offsite-ads fees per sale, 2026 rates.
- mercari fee calculator
The 10% selling fee and your payout, current and pre-2025 structures.
Pool care
- pool salt calculator
Pounds and bags of salt to add to reach your target ppm.
- pool bleach calculator
Liquid chlorine dosing by strength percentage, in gallons, ounces or liters.
Gaming
- twitch bits to usd
What bits are worth both directions, plus the cheapest pack combination to buy.
- edpi calculator
DPI × sensitivity with cm per 360 for CS2, Valorant, Overwatch 2 and more.
- sensitivity converter
Carry the exact same aim between games — cm-per-360 math, any pair of titles.
Work & time
- timecard calculator
Weekly hours from daily in/out times minus unpaid lunch, with overtime pay.
- minutes to decimal hours converter
h:mm to decimal and back instantly, with a conversion chart.
- prorated rent calculator
Daily rate by move-in day under both the actual-days and 30-day methods.
Garage
- tire size calculator
Compare two markings like 225/65R17 vs 235/65R17 — diameter, width, speedo error.
- nm to ft-lbs converter
Torque in newton-meters, foot-pounds, inch-pounds and kgf·m in one box.
Craft & home brew
- epoxy resin calculator
Gallons from area × thickness, split by mix ratio (1:1, 2:1, anything).
- candle wax calculator
Wax weight by weight per jar count, pour fill and fragrance load.
- abv calculator
Alcohol by volume from original and final gravity, both standard formulas.
Canadian tax
- reverse HST calculator
Pull HST or GST out of a receipt total — Ontario and every province's rate.
Pets
- dog food calculator
Daily calories and cups from your dog's weight and activity level.
Why these calculators are different
Most calculator pages give you a number and stop. Every page here gives you three things on top of the answer. First, the formula in plain words — you can redo the math on paper or in a spreadsheet. Second, a worked example with real numbers, so you can see the tool agree with arithmetic you trust. Third, a sources and review date section: wherever a page quotes a payment fee, a tax rate, or a material yield, it says where that number came from and when it was last checked, and the number is editable right on the page so you can match your own statement or dashboard.
The tools run entirely in your browser. There are no accounts, no sign-ups, no tracking pixels and no external requests of any kind — each page works offline once loaded. Nothing you type is sent anywhere.
Last reviewed: October 2026.