First-time room painter
Keep exclusions on their measured face.
Measure each face, exclusions and coats; inspect per-face arithmetic.
Can reproduce source quantities without treating arithmetic as product or purchase approval.
Paint & Coating Calculator
Paint Calculator. Measure individual paint faces with their own openings and coats. Compare product-specific volume ranges, real containers, matching stock and optional cost.
Specialist tool for Painting DIY1 documented formula2 guided projectsPrivate in your browser
Use this result well
A quick decision brief for this specific tool
Inputs that matter
Independent rectangular faces with own exclusions and coats; one exact coating and per-coat spread range
Output to expect
Both volume endpoints, actual uniform-container counts, matching-stock and reserve reconciliation, optional coating-only cost, original-unit JSON and explicit Project Save
How it works
Divide the summed coat-area by each spread endpoint, add only entered allowance and reserve, subtract verified usable matching stock and round to the actual container size
- Lower spread requires more coating; this range is not a probability interval or a guaranteed purchase. No floor-area multiplier or substrate-specific rate is invented.
- One exact coating per record. Primer compatibility, preparation, exposure, drying and occupancy require current product evidence and responsible review. Blank price stays unestimated; no automatic Project approval.
Choose your path
Built around the job you need to finish
Create measured face-by-face single-coating records with owned exclusions/coats and actual-container endpoints.
Mixed-unit estimator
Retain original measurement and package units with a reviewable quote.
Switch display units, edit measured data, change package/source and renew the invalidated quote; download JSON.
Both endpoints reconcile to original source inputs; blank quote remains unestimated.
Narrow-screen Project reviewer
Find input errors and save a source-owned record without checking gates.
Use error links, recover inputs, inspect mobile results and explicitly save in the actual Project.
Named controls and preserved unrelated data support review; saving does not approve work.
Authoritative checks for this tool
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
- Exact finish-paint spread and application scopeBEHR · Specific eggshell product spread depends on application and porosity and excludes spray loss. Not a rate for other coatings.
- Exact primer spread and current instructionsKILZ · Specific Original primer spread and label-led limits; not a universal primer choice, substrate rate, coat count or cure rule.
- US customary and SI conversion factorsNIST · US liquid gallons, liters, feet and square meters. Display conversion does not replace original measurements, supplier contents or quote currency.
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Projects using Paint Calculator
This tool is part of these guided projects. Each project provides step-by-step instructions with checklists and all the tools you need in one place.
Room Painting Decision Record
Coordinate one authorized room-painting scope from people, surface and product evidence through measured quantity scenarios, controlled application, inspection and handoff.
6 steps4 toolsStart project
Bathroom Renovation Decision Record
Coordinate one authorized bathroom alteration through occupant needs, hazard and existing-condition evidence, approved system details, bounded quantity scenarios, inspections, commissioning, and named acceptance.
6 steps4 toolsStart project
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Reference & details
How it works
Updated August 2026
How it works
Updated August 2026Face-owned measurements
Up to eight independent rectangular faces; each owns its exclusions and coats. Different coatings, finishes or spread rates require separate records.
Coat-area = Σ((face width × height − own exclusions) × own coats)Both coverage endpoints
Use current exact product and application evidence. Lower spread requires more coating. This is an arithmetic scenario range, not probability bounds or a guaranteed quantity. No generic substrate rate, loss or coat count is prescribed.
Base volume = coat-area ÷ exact per-coat spreadActual containers and optional cost
Reconcile each endpoint separately using actual net contents of one uniform package size and verified usable matching stock. Blank price is unknown, not zero. Cost covers whole coating containers only, excluding tools, preparation, labor, tax and delivery.
Containers = ceil(max(0, base × (1 + allowance/100) + reserve − matching stock) ÷ container volume)Updated: August 2026
Example Scenarios
12×8 ft less 21 ft² exclusions gives 75 ft² net. Two planned coats give 150 ft² coat-area; at illustrative 250–400 ft²/US gal, no additions or stock: 0.375–0.6 US gal, one one-US-gallon container.
An opening cannot exceed its own face or be deducted from another wall or ceiling. Use separate records when coating, color, finish or spread evidence differs.
Inspect each face and both purchase endpoints, change display units without replacing original measurements, then download or explicitly save the source-owned record.
FAQ
No. These are arithmetic endpoints from your measured scope and product assumptions, not a confidence interval. Actual conditions can fall outside the entered range.
No. Use current exact label/TDS/SDS and representative sample evidence with responsible review. The calculator does not establish product compatibility, primer need, preparation, coat count or return-to-use conditions.
Use a separate record for each exact coating, color, finish and spread range. Full and spot primer passes must use the same primer in one record. Do not combine primer and finish paint volumes.
Display changes preserve original values and units. US liquid gallons are not Imperial gallons; liters are supported. Currency is a label, not a conversion. Blank price is unestimated, while explicit zero means a zero-price quote.
No. JSON retains original units and both exact endpoints. Explicit Project Save records source-owned outputs and provenance; neither checks gates, orders material nor approves work.
About Paint Calculator
Measure individual paint faces with their own openings and coats. Compare product-specific volume ranges, real containers, matching stock and optional cost. Up to eight independent rectangular faces; each owns its exclusions and coats. Different coatings, finishes or spread rates require separate records. Start with your own data or a clearly labeled illustration.