Calculators that show their work.

Radiation safety

Dose rate, shielding, decay and unit conversions for gamma sources — educational estimates with cited constants.

• Gamma dose rate, activity & shielding calculator

  Dose rate from a point source at any distance, through lead, steel or concrete — or solve for activity, distance or shield thickness.

• Radioactive decay & half-life calculator

  Remaining activity, elapsed time, original activity or half-life, with presets for common isotopes.

• Radiation unit converter: Sv ↔ rem, Gy ↔ rad, Bq ↔ Ci

  Convert dose and activity units and turn absorbed dose into equivalent dose with ICRP 103 weighting factors.

By isotope: Cs-137 · Co-60 · Ir-192 · Am-241 · I-131 · Tc-99m · Ra-226 · F-18 · Na-22

Learning the basics? Try the free SMR & radiation-safety study guide and quizzes.

GPU & CPU hosting

Is renting out your spare compute worth the electricity? Net profit per hour and month, and break-even.

• GPU hosting profitability calculator

  Net $/hour, $/month and break-even for renting out GPUs, from board power, electricity price and payout.

• CPU server hosting profitability calculator

  Per-core or per-server payouts against power cost: is your spare server worth renting out?

Equipment & job costing

What a machine really costs you per operating hour, for bidding and job costing.

• Equipment cost per hour calculator

  Owning and operating cost per hour for an excavator, skid steer, truck or any machine.

Tracking job costs all season? See our ready-made spreadsheet workbooks.