Free Online Calculators
524 fast, clear calculators for construction, money, home projects and more. Every calculator shows its formula, a worked example and its assumptions.
Aggregate Price Comparison Calculator
Convert a gravel, stone or sand quote between price per ton and price per cubic yard by density, add delivery, and compare with 50 lb bags, including the break-even quantity.
Open calculator →Concrete Bags Calculator
How many 40, 50, 60, 80 or 90 lb bags of concrete mix a known volume takes, with the mixing water and the number of mixer batches.
Open calculator →Concrete Column and Pier Calculator
Concrete volume and bags for round tube-form or square piers from diameter or side, height and count, with a table of cubic feet per foot for common tube sizes.
Open calculator →Concrete Cost Comparison Calculator
Compare bagged concrete mix with ready-mix delivery for one volume, from your own prices, and find the break-even volume above which ready-mix costs no more.
Open calculator →Concrete Curb Calculator
Concrete volume and bags for a straight curb or a curb and gutter from the profile dimensions and the total length, with waste.
Open calculator →Concrete Driveway Calculator
Concrete yards, gravel base tons, wire mesh or rebar, control joints and material cost for a driveway, patio or sidewalk from its size and thickness.
Open calculator →15 vs 30 Year Mortgage Calculator
Compare a shorter and a longer mortgage term at their own rates: monthly payment, total interest, equity built after a number of years, and what investing the lower payment's savings could grow to.
Open calculator →401(k) Calculator
Estimate how your 401(k) balance could grow based on contributions, employer matching, salary growth, and investment returns.
Open calculator →401(k) Contribution Calculator
Turn a 401(k) salary percentage into dollars per paycheck and per year, see the IRS limit with catch-up for your age, the percentage that reaches it and the paycheck where you hit it.
Open calculator →401(k) Employer Match Calculator
Work out your annual 401(k) employer match from your salary and a tiered match formula, the contribution that captures the full match, and how much match you leave behind by contributing less.
Open calculator →72(t) SEPP Calculator
Annual substantially equal periodic payment you can take from an IRA before 59½ without the 10% penalty under each IRS method (RMD, amortization, annuitization), and how long the payments must continue.
Open calculator →Adjustable-Rate Mortgage Calculator
Project the payments on a 5/1, 5/6, 7/6 or 10/6 hybrid ARM from its initial rate, margin and caps, under an index path you choose and under the worst case where every cap is hit.
Open calculator →Area Rug Size Calculator
Minimum area rug dimensions and the smallest standard rug size for a living room seating group, a dining table or a bed, with the bare floor left at the walls of the room.
Open calculator →Attic and Crawl Space Ventilation Calculator
Net free vent area for an attic or crawl space from its floor area under the typical 1/150, 1/300 or 1/1,500 rule, split into intake and exhaust, with the feet of ridge or soffit vent or the number of vents.
Open calculator →Baseboard Trim Calculator
Work out the linear feet and number of 8, 12 or 16 ft lengths of baseboard, and of shoe or quarter round, for a room from its size or perimeter less the doorways, with a waste allowance and the cost of the lengths at your price per foot.
Open calculator →Blown-In Attic Insulation Calculator
Bags of blown cellulose or fiberglass to bring an attic to a target R-value, from the attic area, the insulation already there and the coverage chart printed on the bag.
Open calculator →Cabinet Paint Calculator
Quarts of cabinet enamel and primer from the number and size of doors and drawer fronts, face-frame length, end panels and the number of coats.
Open calculator →Carpet Calculator
Linear feet and square yards of carpet or sheet vinyl to cut from a roll, with the number of drops, seams and pad rolls, from the room size and roll width.
Open calculator →Annual Lawn Nitrogen Program Calculator
Split a yearly lawn nitrogen total into equal applications and get the pounds of fertilizer product per application and per year for your lawn, compared with published seasonal totals for your grass.
Open calculator →Bulk vs Bagged Mulch and Soil Cost Calculator
Compare the total cost of bagged mulch, soil or compost with a bulk delivery for the same volume, and find the break-even volume above which bulk is cheaper.
Open calculator →Compost Bin Size and Yield Calculator
Volume of a square or round compost bin or pile, whether it reaches the 3 × 3 × 3 ft (1 cu yd) minimum for hot composting, and how much finished compost the raw material should make.
Open calculator →Compost C:N Ratio Calculator
Carbon-to-nitrogen ratio of a compost mix from the weight, moisture, nitrogen and carbon (or C:N) of each ingredient, weighted by dry matter, and how much of one ingredient brings the mix to a target ratio.
Open calculator →Core Aeration Calculator
Holes per square foot, total holes, the share of the lawn surface opened and the soil pulled out by a core aerator, from tine spacing, core size and passes, with the topdressing needed to refill the holes.
Open calculator →Dethatching Calculator
Whether a measured thatch layer is at or above a chosen threshold, and the cubic feet, cubic yards and lawn bags of debris to expect from dethatching an area.
Open calculator →Annual Fuel Cost Calculator
Estimate yearly and monthly fuel spending from miles per year, your city/highway split, city and highway MPG and fuel price, and compare two vehicles side by side.
Open calculator →Auto Loan Calculator
Calculate your monthly car payment, total interest and total cost from the vehicle price, down payment, trade-in, sales tax, APR and loan term.
Open calculator →Auto Loan Refinance Calculator
Compare finishing your current car loan with refinancing it: the new monthly payment, the change in payment, the remaining interest on each loan and the net savings after refinance fees.
Open calculator →Brake Pad Life Calculator
Estimate the miles left on a set of brake pads from the measured pad thickness, the thickness when new, the miles driven since they were fitted and the replacement thickness, plus the cost per mile of the brake job.
Open calculator →Car Depreciation Calculator
Estimate what a car is worth after each year of ownership from its purchase price and depreciation rates you can edit (a typical curve by year, or one annual rate), with the total loss and the value at a chosen year.
Open calculator →Car Down Payment Calculator
Find the down payment that brings a car loan to a target monthly payment, and compare the payment and interest at several down-payment amounts against a 20% guideline.
Open calculator →Cable Tray Fill Calculator
Total cross-sectional area of multiconductor cables from their count and outside diameter, compared with the allowable fill area you look up for your cable tray.
Open calculator →Capacitor Charge and Energy Calculator
Charge (Q = C × V) and stored energy (E = ½ × C × V²) of a capacitor from its capacitance and voltage, or the capacitance needed to store a given energy at a given voltage.
Open calculator →Capacitor Code Calculator
Capacitance in pF, nF and µF from a three-digit ceramic capacitor code such as 104 and its tolerance letter, or the code that marks a given capacitance.
Open calculator →Electric Heating Cost Calculator
Cost per hour, day and season of electric resistance heat from heater watts or the BTU/h you need, the same heat from a heat pump at a chosen COP, and the cost per million BTU of each.
Open calculator →Electricity Cost Calculator
Work out how many kilowatt-hours an appliance uses and what it costs to run per day, month and year from its watts, hours of use and your electricity rate.
Open calculator →Equipment Grounding Conductor Size Calculator
Proportional upsize of an equipment grounding conductor when the circuit conductors are made larger than their minimum size, from the minimum EGC size you look up and the before and after circuit conductor sizes.
Open calculator →Age Calculator
Find an exact age in years, months and days on any date, the total days lived, and how many days remain until the next birthday.
Open calculator →Angle Between Two Lines Calculator
Find the acute and obtuse angles between two lines from their slopes, direction vectors, two points on each, or their equations, and whether they are parallel or perpendicular.
Open calculator →Angle Converter
Convert an angle between degrees, radians, gradians, turns, arcminutes, arcseconds and milliradians, and between decimal degrees and degrees-minutes-seconds.
Open calculator →Angle of Elevation and Height Calculator
Find the angle of elevation and line-of-sight distance from a horizontal distance and a height, or the height of an object from the distance and the angle, allowing for the observer's eye height.
Open calculator →Annulus (Ring) Area Calculator
Find the area of the ring between two concentric circles from the inner and outer radii or diameters, plus the ring width and both circumferences.
Open calculator →Area Converter
Convert an area between square millimetres, centimetres, metres, kilometres, hectares, square inches, feet, yards, acres and square miles using the exact legal definitions, with the factor shown.
Open calculator →Baker's Percentage Calculator
Turn a bread formula's ingredient weights into baker's percentages (flour = 100%), or turn baker's percentages into ingredient weights from a flour weight or a target total dough weight.
Open calculator →Baking Pan Size Conversion Calculator
The factor to scale a recipe from one baking pan to another (round, square, rectangular, loaf, Bundt or muffin), by bottom area or by volume, and how much deeper or shallower the batter is if the recipe is not scaled.
Open calculator →Baking Ratio Calculator
Turn a classic baking ratio (bread, pie dough, cookie, pancake, biscuit, pound cake, or your own) into ingredient weights from the weight of one ingredient or the total batch you want.
Open calculator →Batch Yield and Servings Calculator
How many servings a batch makes from its total weight or volume and the portion size, how many pieces a pan cut into a grid gives, or how big a batch a number of servings needs.
Open calculator →Butter Conversion Calculator
Convert butter between US sticks, tablespoons, teaspoons, cups, ounces, pounds, grams and 250 g European blocks from any one of them.
Open calculator →Cake Servings Calculator
How many party or wedding slices a round, square or sheet cake serves, summed across tiers and checked against the Wilton serving chart, or the cake size a guest count needs.
Open calculator →Absenteeism Cost Calculator
Work out the absence rate from days lost, headcount and scheduled workdays, and the cost of unplanned absences from loaded daily pay, the cost of covering absent shifts and lost productivity.
Open calculator →Billable Utilization Calculator
Work out billable utilization from billable and available hours for a person or a team, the revenue those hours bring at a billing rate, the revenue at a target utilization, and the utilization needed to cover loaded labor cost.
Open calculator →Break-Even Calculator
Find how many units you must sell, and the revenue you must earn, to cover your fixed and variable costs.
Open calculator →Bundle Pricing Calculator
Bundle price, the customer's saving and the bundle margin from up to six item prices and costs and a bundle discount, compared with selling the items separately.
Open calculator →Charm Price Rounding Calculator
Round a calculated price up or down to a charm ending such as .99, .95, .49 or a whole $5 or $10, and see the margin and markup at the rounded price.
Open calculator →Clearance Markdown Calculator
Weeks to clear remaining stock at a markdown from units on hand, the current weekly sell rate and an assumed sales lift, with the cash recovered and the margin kept against cost.
Open calculator →Arc Radius from Chord and Rise Calculator
Find the radius, arc length, central angle and trammel pivot position for an arched rail, tabletop edge or door top from the chord width and the rise at the centre.
Open calculator →Band Saw Blade Length Calculator
Blade length for a two-wheel or three-wheel band saw from the wheel diameters and center distances, and the blade speed in feet per minute at a wheel's RPM.
Open calculator →Band Saw Blade Width and TPI Calculator
The widest band saw blade that can cut a given curve radius, from a blade maker's minimum-radius chart, and the teeth-per-inch range that keeps a chosen number of teeth in the cut for a stock thickness.
Open calculator →Biscuit Joint Layout Calculator
Lay out a biscuit joint on an edge or a miter: the number of biscuits, their centre marks, the fence height that centres the slot in the stock, and whether the biscuit fits the joint.
Open calculator →Board Cut List Optimizer
Find how many stock boards of a given length a list of part lengths needs, allowing for saw kerf and end trim, and which parts to cut from each board.
Open calculator →Board Foot Calculator
Calculate board feet from thickness, width and length, total it across a stack of boards, and price the order per board foot.
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