Psychrometry
GPP and dew point.
Water · Calculator
Free · no login
Product overview
Enter a temperature and relative humidity and this tool returns grains per pound (GPP), dew point, and the humidity ratio at sea level. Reach for it when you are reading a drying chamber and need to convert a psychrometer's temp/RH into the actual moisture load the air is carrying — the number that tells you whether your dehumidifiers are winning. It is the daily-monitoring math that turns a meter reading into a documented GPP you can log and defend.
The tool works the standard sea-level psychrometric relationships. It converts temperature to Celsius, computes saturation vapor pressure from the Buck equation, scales by relative humidity to get actual vapor pressure, then derives the humidity ratio (mass of water per mass of dry air) from the ratio of vapor pressure to atmospheric pressure. Multiplying that ratio by 7000 gives GPP — grains of moisture per pound of dry air, the unit IICRC S500 uses for drying comparisons. Dew point comes from the Magnus approximation. All at standard sea-level atmospheric pressure (101.325 kPa); high-altitude jobs read differently.
Product details
- Sold by
- Mensuria
- Product category
- Free field tool · Calculator
- Delivery method
- Web app · no login
- Cost
- Free
Highlights
- Deterministic — the same inputs give the same result, every time.
- Built for the trade, sized to feed Xactimate line-item quantities.
- Free — no login, no card.
- Works from a phone at the loss.
Vendor insights
Mensuria writes a neutral scope built to survive review — every line item sourced to a photo, anything unprovable held back and flagged for you. It never files the estimate; a licensed adjuster confirms every line and stays the adjuster of record. Mensuria is independent and not affiliated with Verisk or Xactimate; “Xactimate-ready” means the worksheet is organized for Quick Entry.
Pricing
This tool is free — no login, no card. The full scope-drafting product is priced below; your first claim is free.
Details
Delivery method
Mensuria is a web app — nothing to install. You work a claim in the browser and export a room-grouped, Xactimate-ready worksheet (codes, quantities, descriptions) organized for Quick Entry. There is no native .ESX import; you key the reviewed line items into Xactimate and stay in control.
Terms and conditions
Use of Mensuria is subject to our Terms of Service. Your first claim is free with no card; paid plans are billed monthly and cancel anytime.
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Support
Support
Reach the team at support@mensuria.com . You will hear back from people who have written a scope, not a ticket queue.
Onboarding
Your first claim walks you through capture, draft, review, and export step by step, so you are productive on claim one — no training required.
Refund policy
Monthly plans cancel anytime; the CAT Season Pass is a one-time add-on with no commitment.
Common questions
GPP — grains per pound — is the amount of moisture in a pound of dry air, and it is the honest measure of how wet the air is, independent of temperature. Relative humidity alone misleads because warm air holds more water, so 50% RH at 90°F carries far more moisture than 50% at 60°F. In structural drying you compare GPP inside the chamber to GPP outside (or at the dehumidifier's inlet and outlet) to prove the equipment is removing moisture. Falling GPP over your daily logs is the documentation that the drying is working.
Take temperature and RH at several points — the affected area, the dehumidifier outlet, unaffected reference air, and outside — then convert each to GPP with this tool. The dehumidifier outlet should read markedly lower GPP than the chamber; that gap is your proof the unit is pulling water. Chamber GPP should trend down day over day toward the outside or reference reading. Log all of it. A stalled or rising chamber GPP tells you a unit failed, the chamber was opened, or you are under-equipped — and the readings tell you which before you lose drying days.
Relative humidity is the percentage of moisture the air is holding relative to what it could hold at that temperature — it moves as temperature moves even when actual moisture is constant. Dew point is the temperature at which that air would reach saturation and condense; it is a fixed measure of actual moisture content. In drying, dew point matters for secondary damage: cold surfaces below the dew point will sweat and grow the loss. This tool gives you both from one temp/RH reading, plus the GPP that ties them together.
Yes. This tool computes at standard sea-level atmospheric pressure (101.325 kPa). At elevation the air is thinner, atmospheric pressure drops, and the humidity ratio and GPP for a given temp/RH shift — GPP runs higher for the same reading than the sea-level figure shown here. For a Denver or mountain-region loss, treat the output as a close approximation and verify against a calibrated, altitude-aware meter on site. The dew point figure is less sensitive to altitude than the GPP, but on high-elevation jobs your documented readings should come from the instrument.
Air movers and dehumidifiers.
Duration from conditions.
Cat-1/2/3, Class 1-4.
- Water
Treatment surface sizing.