# KLM Labs > KLM Labs makes small iPhone apps for tradespeople, contractors and one-person businesses, and a few for everyone. This site (https://klmlabs.app/) has each app's facts (what it does and doesn't, its plans and prices, checked against the App Store), plus free invoice templates and printable construction charts made with the apps' own layouts and formulas. Every link below is the Markdown copy of a page on https://klmlabs.app; each copy names its HTML page as canonical, and the HTML page links its copy (rel="alternate" type="text/markdown"). Each copy carries the page's facts with their sources and the app's plain App Store link. Facts and prices were checked against the App Store on the date each copy gives. Contact: support@klmlabs.app (every address: https://klmlabs.app/contact/). All our apps on the App Store: https://apps.apple.com/us/developer/mayank-kumar-grover/id6815655787 ## Apps - [Invoice Maker by KLM Labs](https://klmlabs.app/invoice-maker/index.md): An iPhone and iPad app for making invoices and estimates on the job, offline and without an account. Free to download, with in-app purchases. App Store: https://apps.apple.com/us/app/invoice-maker-estimates-app/id6815655785 - [Construction Calculator by KLM Labs](https://klmlabs.app/construction-calculator/index.md): Feet, inches and fractions done exactly, plus stairs, roof pitch, rafters and concrete. iPhone and iPad; free to download, with in-app purchases. App Store: https://apps.apple.com/us/app/fraction-feet-inch-calculator/id6816445977 - [Flip Clock by KLM Labs](https://klmlabs.app/flip-clock/index.md): A big flip, digital or retro LED clock for your nightstand or desk, in your colors, with alarms that ring on Silent and no ads. iPhone and iPad; free to download, with in-app purchases. App Store: https://apps.apple.com/us/app/flip-clock-big-digital-alarm/id6819014371 ## Invoice Maker pages - [Free invoice templates by trade](https://klmlabs.app/invoice-maker/invoice-templates/index.md): Free invoice templates for consultants, electricians, handymen, roofers, landscapers, caterers and photographers: filled-in PDFs, every line explained. - [Catering invoice template](https://klmlabs.app/invoice-maker/invoice-templates/catering/index.md): A free catering invoice template PDF, filled in: per-guest menu prices times the final headcount, staff hours, rentals, delivery and one sales tax rate. - [Consulting invoice template](https://klmlabs.app/invoice-maker/invoice-templates/consulting/index.md): A free consulting invoice template PDF, filled in: hours at an hourly rate, a fixed-fee item, expenses at cost and net 30 terms, with each line explained. - [Electrician invoice template](https://klmlabs.app/invoice-maker/invoice-templates/electrician/index.md): A free electrician invoice template PDF, filled in: labor hours, the panel and parts as separate lines, the permit fee, and the estimate it came from. - [Handyman invoice template](https://klmlabs.app/invoice-maker/invoice-templates/handyman/index.md): A free handyman invoice template PDF, filled in: a trip charge, three small jobs on one visit each with its own hours, and materials on one line. - [Landscaping invoice template for lawn care](https://klmlabs.app/invoice-maker/invoice-templates/landscaping-lawn-care/index.md): A free landscaping invoice template PDF, filled in: a month of weekly mowing visits, a fall cleanup, mulch by the cubic yard and pruning hours. - [Photography invoice template](https://klmlabs.app/invoice-maker/invoice-templates/photography/index.md): A free photography invoice template PDF, filled in: session fee, final images, rush delivery, prints, travel, and a plain-words usage license line. - [Roofing invoice template](https://klmlabs.app/invoice-maker/invoice-templates/roofing/index.md): A free roofing invoice template PDF, filled in: tear-off and shingles by the square, flashing and vents by the linear foot, decking and the permit. - [Net 30 invoice terms: what they mean and how to write them](https://klmlabs.app/invoice-maker/invoicing/net-30-payment-terms/index.md): Net 30 means an invoice is due 30 days after its date. How to write net 30 payment terms, sample late-fee wording, and a free net 30 invoice PDF. ## Construction Calculator pages - [What is a board foot, and how to calculate board feet](https://klmlabs.app/construction-calculator/board-feet/index.md): A board foot is 144 cubic inches of lumber, 12" × 12" × 1". How to calculate board feet from nominal sizes, with a printable chart for 1x4 to 6x6. - [How many bags of concrete in a yard: 80, 60 and 40 lb bags](https://klmlabs.app/construction-calculator/concrete-bags-per-yard/index.md): About 45 bags of 80 lb concrete make a cubic yard, 60 of 60 lb, 90 of 40 lb. A slab chart in yards and bags with 10% waste, as a free printable PDF. - [Crown molding angles chart for cutting crown flat on a miter saw](https://klmlabs.app/construction-calculator/crown-molding-angles/index.md): Miter and bevel settings for 52/38 and 45/45 crown molding cut flat on a compound miter saw, for wall corners from 60° to 150°. Free printable chart. - [Fraction to decimal chart for inches, with millimeters and feet](https://klmlabs.app/construction-calculator/fraction-decimal-inch-chart/index.md): A fraction to decimal chart for every 64th of an inch, with millimeters and decimal feet, plus inches to decimal feet. Free printable PDF, US Letter. - [Construction charts and guides](https://klmlabs.app/construction-calculator/guides/index.md): Seven printable construction charts: fraction to decimal, roof pitch, board feet, concrete bags, crown molding angles, stair rise and run, and square feet. - [Roof pitch chart: 1/12 to 24/12 in degrees, slope and rafter length](https://klmlabs.app/construction-calculator/roof-pitch-chart/index.md): A roof pitch chart from 1/12 to 24/12: the angle in degrees, slope percent, plumb and seat cuts, and rafter length per foot of run. Free printable PDF. - [How to calculate square footage from inches and fractions](https://klmlabs.app/construction-calculator/square-feet-from-feet-and-inches/index.md): Multiply length × width in inches and divide by 144 for square feet. Worked examples with feet, inches and fractions, done exactly, and a printable chart. - [Stair rise and run code: IRC 2021 limits with worked layouts](https://klmlabs.app/construction-calculator/stair-rise-and-run/index.md): The 2021 IRC limits for stair risers (7-3/4" max) and treads (10" min), the 7-11 rule, and worked stair layouts for rises from 2' to 10'. Free PDF. ## Site - [Small iPhone apps for people who run their own work](https://klmlabs.app/index.md): KLM Labs makes small iPhone apps for tradespeople and solo businesses, starting with Invoice Maker, plus free invoice templates made with the app's layout. - [About KLM Labs](https://klmlabs.app/about/index.md): KLM Labs is a small app studio run by its founder, Mayank Kumar Grover: what we make, how our templates and charts are made and checked, and corrections. - [Contact KLM Labs](https://klmlabs.app/contact/index.md): The KLM Labs email addresses for app and site support, privacy, refunds and the founder. App Store purchases are refunded by Apple; here is how to ask. - [Privacy policy for this website](https://klmlabs.app/privacy/index.md): What klmlabs.app collects: Cloudflare Web Analytics visit counts (no cookies) and a daily count of App Store taps per page. No forms or accounts.