Terms of Use
Effective date: July 14, 2026
These terms govern your use of the Chalk: Construction Calculator iOS application ("Chalk") provided by Lionary LLC. By using Chalk you agree to them, along with Apple's standard Licensed Application End User License Agreement.
Chalk's calculators produce estimates based on the values you enter. They are not a substitute for professional judgment, engineering, or your local building codes. Always verify all dimensions, quantities, spans, and structural values with a qualified professional — and against your plans and applicable codes — before cutting, pouring, building, or ordering materials. You are solely responsible for how you use the results.
What Chalk is
Chalk is a construction calculator for iPhone: a feet-inch-fraction calculator with a purpose-built keypad, dual metric/imperial results, and trade calculators for stairs, rafters, concrete, framing, drywall, tiling, decking, and more — with saved projects and offline operation.
Subscriptions
- Chalk Pro unlocks the full set of trade calculators and saved projects via auto-renewing subscription: $2.99/week or $17.99/year.
- There is no free trial. The free tier (fraction calculator, unit converter, check square, pitch & slope, area & volume) is free without a subscription.
- Payment is charged to your Apple ID account at purchase confirmation. All purchases are handled by Apple.
- Subscriptions renew automatically unless canceled at least 24 hours before the end of the current period.
- Manage or cancel anytime in your App Store account settings (iPhone Settings → your name → Subscriptions); your subscription stays active until the end of the current billing period.
- Prices are shown in the app before purchase and may vary by region.
Your data
Projects, calculations, and settings you create in Chalk are stored on your device and belong to you. There are no accounts; see the Privacy Policy for details.
Acceptable use
Don't reverse-engineer, resell, or misuse the app or its services, and don't use the app in violation of applicable law.
Disclaimer & limitation of liability
The app is provided "as is" without warranties of any kind, express or implied, including fitness for a particular purpose. Calculation results are estimates and may contain errors — from inputs, assumptions, rounding, or defects — and Lionary LLC does not warrant their accuracy, completeness, or suitability for any project. To the maximum extent permitted by law, Lionary LLC is not liable for any indirect, incidental, or consequential damages arising from use of the app, including construction errors, material over- or under-ordering, project delays, or failure to comply with building codes. Your sole and exclusive remedy for dissatisfaction with the app is to stop using it.
Changes
We may update these terms; continued use after an update constitutes acceptance.