Glazing & Windows Calculators
Window U-values, glazing units, sealants, bi-fold doors and glass calculators.
Window U-Value Calculator
Calculate window U-value from glass, frame and spacer thermal performance.
Double Glazing Unit Calculator
Calculate DGU thickness, weight per m² and thermal performance by gas fill.
Window Condensation Risk Calculator
Calculate window condensation risk from internal temperature, RH and dew point.
Sealant and Mastic Calculator
Calculate sealant cartridges from joint volume per window frame.
Window Security Spec Calculator
Determine PAS 24 window security requirements by floor and access level.
Secondary Glazing Calculator
Calculate secondary glazing panel area, frame length and U-value improvement.
Bi-Fold Door Calculator
Calculate bi-fold door structural opening, lintel size and leaf count.
Sliding Door Calculator
Calculate sliding door opening size, track length, structural header and drainage.
Trickle Vent Calculator
Calculate Part F trickle vent equivalent area per room with unit selection.
Roof Window Calculator
Select roof window size by room area for Part L daylight with flashing kit.
Skylight Calculator
Calculate skylight structural opening, kerb depth, upstand and drainage detail.
Bay Window Structural Calculator
Calculate bay window gallows brackets, foundation and roof covering area.
Juliet Balcony Calculator
Calculate Juliet balcony glass panel dimensions and fixing bolt requirements.
Glass Balustrade Calculator
Calculate glass balustrade panel dimensions, base channel and wind loading.
Curtain Walling Calculator
Calculate curtain walling mullion spacing, transom heights and glazing unit sizes.
Acoustic Glazing Calculator
Calculate acoustic glazing Rw rating by glass configuration and laminated options.
Window Replacement Calculator
Calculate window replacement quantities with frame material and U-value comparison.
French Door Calculator
Calculate French door opening width, lintel span and Part L U-value compliance.
Conservatory Glazing Calculator
Calculate conservatory glazing panels, ridge length, eaves beam and valley bars.
Window Board and Sill Calculator
Calculate internal window board and external sill dimensions with drip channel.
Structural Glass Beam Calculator
Calculate structural glass fin and beam sizing for frameless glazing systems.
Window Fire Escape Calculator
Check Part B fire escape window minimum dimensions and cill height requirements.
Door Glazing Calculator
Calculate glass panel sizes, safety glass requirements and Part N zones for doors.
Glass Weight Calculator
Calculate glass weight by type and thickness for handling assessments and structural loading.
Roof Light Sizing Calculator
Select roof window size by room area, daylight requirements and roof covering type.
Window Energy Rating Calculator
Estimate the BFRC window energy rating band from U-value, solar gain and air leakage.
26 free calculators in Glazing & Windows
Glazing & Window Calculators for UK Professionals
Our glazing and window calculators help UK installers, surveyors, and fenestration specialists work to the latest Building Regulations. Part L of the Building Regulations sets strict thermal performance requirements for windows and doors, with replacement windows needing to achieve a Window Energy Rating of at least Band C or a U-value of 1.4 W/m'K or better. These tools make it straightforward to check compliance before ordering materials.
Whether you're calculating glass thickness for large panes to BS 6262, estimating U-values for different glazing configurations, or working out costs for a full house of replacement windows, these calculators cover the essentials. They account for UK-specific factors including frame materials, gas fills, low-emissivity coatings, and warm-edge spacer bars that all contribute to the overall thermal performance of a window unit.
From FENSA-registered installers to architects specifying glazing for new builds, these tools support accurate planning and quoting. All calculations reference current British Standards and Approved Document L, ensuring your glazing specifications meet the energy efficiency targets required for Building Control sign-off across England and Wales.