Choose the decision you need to make
Start with the uncertainty that can change the job. If it is electrical demand, separate running load, startup and lead voltage drop. If it is exposure, use representative magnitude, level and time. If it is task fit, identify the material, operation and all independent stop conditions before looking at a size.
Each guide shows what to record, what the arithmetic can say and what must be confirmed elsewhere. Calculators support that record; they do not replace equipment instructions, assessment or competent advice. You can combine selected records in a printable Job Pack, or browse all calculators.
If several questions apply, begin with a stop condition: unknown material, unresolved services, enclosed fuel-generator location or missing equipment markings. Resolve that before spending time refining quantities.
Power and supply
- Power / 01Use this method
110 V site power
Convert concurrent electrical input to apparent load, distinguish continuous from intermittent transformer ratings, and check actual extension-lead data.
- Power / 02Use this method
Generators on site
Apply the carbon-monoxide location stop first, then organise running loads, one declared start event, rating basis and manufacturer confirmation.
- Power / 03Use this method
Battery runtime and packs
Separate nominal and usable watt-hours, trigger time and elapsed time without making a compatibility or runtime promise.
Exposure and dust
- Exposure / 01Use this method
Vibration and noise
Build separate daily HAVS and noise records from representative inputs, understand action/limit values and avoid arithmetic averaging of decibels.
- Control / 02Use this method
Dust control at source
Match extraction or water suppression to material and task, confirm capture performance, and recognise specialist-hazard stops.
Exposure and control outputs are planning records. A result below a threshold is not reassurance that the assessment and control duties are complete.
Task and cost planning
- Fit / 01Use this method
Angle-grinder discs
Distinguish cutting, grinding and polishing, then check markings, diameter, RPM, interface, guard and stated depth independently.
- Fit / 02Use this method
Core drilling
Define the hole and stop for unresolved structure, reinforcement, services, anchorage, breakthrough, water or dust before routing equipment.
- Cost / 03Use this method
Hire or buy
Compare your own like-for-like prices against programme, utilisation, maintenance, storage, downtime and actual terms.
How the guides are checked
Consequential claims carry adjacent markers for legislation, HSE guidance, manufacturer/technical input, conservative Job Lab policy or transparent arithmetic. The source register records canonical links and truthful date labels; Methodology explains formula versions, rounding, fail-closed behaviour and change control.
Where a guide uses a model-specific rating or manufacturer range, keep that example tied to its cited source. Do not transfer it to another product or treat a range boundary as a universal selection rule.