Calculators
Decision-support tools for sizing, cost, capacity, runtime, ownership, and other practical planning questions.
Calculate a person's age at death from their birth and death dates by entering the elapsed years, months, and days between those dates. The result uses a 365-day year and a 30-day month for a clear estimate.
Calculate the elapsed difference between two dates of birth in years, months, and days. Enter each date as a year, month, and day; the result is an approximate age gap based on calendar-day lengths.
Estimate atmospheric pressure at a chosen elevation using the standard-atmosphere barometric model. Enter sea-level pressure and altitude; the result assumes a constant standard temperature profile and is an estimate.
Estimate the unused internal volume of an archive box by subtracting the volume occupied by a document stack from the box's dimensions. The result is a volume estimate, not a count of folders or sheets.
Calculate the combined area in square meters of labels for archive boxes from label width, label height, and the number of boxes.
Calculate the elapsed year span between two archive dates by subtracting the start year from the end year. Enter whole years from 1 to 3000. The result is a year difference and does not count inclusive calendar years or verify archival records.
Estimate archive copying costs by multiplying the number of pages by the per-page charge and adding any handling cost. Enter the rates supplied by the archive for a planning estimate.
Estimate archive research costs by combining an hourly research rate with research time, copying expenses, and travel costs. Enter amounts in your chosen currency; the estimate does not include costs you leave out.
Estimate the total linear shelf length needed for archive boxes from their width, count, and optional clearance between boxes. The estimate assumes every box is stored side by side in one continuous row.
Estimate fuel used and operating time from your boat's fuel flow and available fuel. This simple model assumes the entered fuel flow remains constant.
Estimate a planning horsepower figure from a boat's fully loaded weight using a simple displacement-boat rule of thumb. This worksheet assumes a displacement hull and does not determine safe, legal, or manufacturer-approved engine capacity.
Estimate a boat’s still-water range from usable fuel, fuel consumption, and a planning reserve. The estimate assumes steady fuel use and does not account for changing conditions.
Estimate a boat's average speed from distance traveled and elapsed time. Enter nautical miles and hours to get speed in knots.
Estimate the upward buoyant force on a fully submerged object using the surrounding fluid density, displaced volume, and local gravitational acceleration. The estimate assumes a static fluid and does not account for drag, waves, or changing immersion.
Estimate the combined ground footprint of camp shelters by multiplying shelter length, width, and the number of shelters. The result assumes each shelter has a rectangular footprint and excludes spacing, guy lines, entrances, and shared or overlapping areas.
Calculate the rectangular footprint of a camp sleeping pad from its length and width, using meters and returning square meters.
Convert one latitude coordinate from degrees, minutes, and seconds (DMS) to signed decimal degrees. Choose the hemisphere to set the sign.
Estimate the dew point from air temperature and relative humidity using the Magnus approximation. Enter temperature in degrees Celsius and relative humidity as a percentage.
Estimate absolute ambient pressure at a given seawater depth from the surface atmospheric pressure, using an approximate seawater pressure increase of 1 bar per 10 meters.
Estimate the storage cost for family archive boxes from the number of boxes, monthly cost per box, and storage duration.
Estimate hiking time from route distance, average hiking speed, and planned break time.
Estimate the total mass of food to pack by multiplying hiking days, meals per day, and the average grams of food per meal.
Estimate level-equivalent moving time by dividing route distance by your sustainable average hiking speed. This estimate excludes elevation, terrain, breaks, and changing conditions.
Estimate cumulative uphill elevation gain by multiplying the number of climbs by the elevation gained on each climb. Enter values in feet.
Estimate the remaining stated value of a cargo after subtracting lost units. Enter cargo and loss quantities in the same units, then enter the value per unit in your chosen currency.
Estimate the geometric volume of a rectangular cargo space from its length, width, and height in feet. This is a simple box-shaped estimate and does not account for the hull's curves, obstructions, or historical cargo rules.
Estimate the total pounds of food provisions for a voyage by multiplying crew size by daily food per person and voyage duration. This planning model assumes a steady daily ration and does not account for water, spoilage, packaging, or changes in rationing.
Estimate the total water quantity for a historic voyage by multiplying crew size, days at sea, and the assumed daily water allowance per person. This simple model treats the allowance as constant and does not account for storage losses or changing conditions.
Estimate the value of a past amount in a later year using an annual inflation rate that you provide. This constant-rate model shows an illustrative purchasing-power equivalent and does not look up historical price indexes.
Estimate a vessel's displaced volume from its measured displacement length, beam, draft, and block coefficient. This simplified geometric model reports volume, not vessel weight or a seaworthiness assessment.
Estimate a displacement boat’s theoretical hull speed from its waterline length using the traditional square-root rule. The result is an approximate speed in knots, not a guaranteed operating speed.
Estimate static under-keel clearance by adding chart datum offset to water depth and subtracting vessel draft. Enter all measurements in meters.
Convert a speed in knots to its equivalent in kilometers per hour using the standard nautical conversion factor.
Convert a speed in knots to miles per hour using the standard nautical-mile conversion factor. Enter a speed in knots to see its equivalent in mph.
Convert a measured distance on a map into the corresponding ground distance using the map scale ratio. Enter the map distance and the scale denominator, then choose units for each measurement.
Estimate the fuel cost of a boat trip from route distance, vessel fuel consumption, and the price paid per unit of fuel. The estimate assumes steady average consumption over the stated distance.
Estimate a maritime archive research budget by combining researcher hours at an hourly rate with the cost of requested copies.
Estimate the floor area occupied by display cases and visitor walkways in a maritime exhibit. Enter case count, the length and width of each case, and the walkway area. This simple planning estimate assumes rectangular cases and adds the supplied walkway area; it does not account for circulation requirements, wall displays, irregular shapes, or building constraints.
Convert a distance in nautical miles to kilometers using the standard international conversion of 1 nautical mile to 1.852 kilometers.
Convert a distance in nautical miles to statute miles using the standard conversion factor of 1 nautical mile = 1.15078 miles.
Estimate the total covered shelter area by multiplying the number of attendees by the planned shelter area per person. The estimate assumes one consistent area allowance for every attendee and does not account for equipment, layouts, access routes, or weather conditions.
Estimate the combined area of parchment sheets in square metres from sheet dimensions in centimetres and the number of sheets. Assumes every sheet is rectangular and uses the same dimensions.
Use your own inputs to calculate the result for sail area.
Estimate underway time for a sailing passage by dividing planned route distance by average speed through the water. This basic estimate excludes stops, current, weather changes, and navigation detours.
Estimate transcription labor cost from the number of logbook pages, average minutes per page, hourly rate, and any fixed setup cost.
Calculate the vertical tidal range by subtracting a low-water level from a high-water level measured from the same chart datum and in the same units.
Estimate a vessel's displacement in metric tonnes from water density and the volume of water displaced. This simplified calculation assumes the entered volume represents the vessel's actual displaced volume at the condition being assessed.
Estimate the volume of a solid object from the water-level rise in a calibrated container. Enter the container's inside dimensions and the water-level rise to calculate displaced volume, assuming a vertical-sided container and complete submersion.
Estimate the average wave period from the time it takes a measured number of waves to pass a fixed point.
Estimate the speed of a wave from its frequency and wavelength using the relationship between wave speed, frequency, and wavelength. This model assumes a regular traveling wave and user-supplied measurements.