Free tools
Free calculators for UK civils.
For QSs, commercial managers, site engineers and subcontractors. No sign-in, and nothing you type leaves your browser.
Payment dates calculator
Due date, payment notice, pay less notice and final date under the Scheme or your contract.
OpenLate payment interest calculator
Statutory interest at 8% over the reference rate, plus the fixed-sum compensation.
OpenWorking days calculator
Days between dates, or a date plus or minus days, for each UK nation.
OpenAggregate & concrete calculator
Volumes and tonnes with waste, plus concrete truck loads.
OpenPipe gradient calculator
Convert gradients, find the fall and invert levels along a run.
OpenOS grid reference converter
Grid references, eastings/northings and lat/long, both ways.
OpenNEC4 compensation event timescales
Track notification, quotation, failure-notice and assessment deadlines for an NEC4 ECC compensation event.
OpenCIS deduction calculator
Calculate CIS deductions at 0%, 20% or 30%, qualifying direct costs, invoice VAT and net subcontractor payment.
OpenVAT domestic reverse charge checker
Check the UK construction VAT domestic reverse charge with a short CIS, VAT registration, end-user and staff-supply question flow.
OpenRetention calculator
Calculate construction retention, caps and staged releases, or NEC X16 retention above the retention free amount.
OpenDelay damages calculator
Calculate delay damages using calendar days or weeks, amended completion dates, daily or weekly rates and an optional cap.
OpenLevelling reduction calculator
Reduce levelling readings by rise and fall or height of collimation, check arithmetic and misclosure, adjust by setup and export CSV.
OpenNEC X1 price adjustment calculator
Calculate NEC X1 PAF from user-entered indices, proportions and non-adjustable share, with Options A/B and C/D adjustment amounts.
OpenNEC weather compensation event checker
Compare monthly NEC4 ECC weather measurements with 1-in-10-year values, identify excess and check the Contract Data location and completion context.
OpenAdjudication timetable
Scheme referral, appointment, decision and correction deadlines.
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