Every calculator on this site assumes you already know what it's calculating. This page covers that. Each entry defines a term in plain language, in two paragraphs at most, and links to the tool that puts it to work. 36 terms so far, grouped by the field they come from, and the list grows as tools are added.
No term matches that.
Finance and business
Margin vs. markup
Both describe profit, measured against different bases. Margin is profit as a share of the selling price; markup is profit as a share of the cost. Buy for $80, sell for $100, and the $20 profit is a 20% margin and a 25% markup. Because the denominators differ, the two numbers drift further apart as they grow, and quoting one when you mean the other is a common pricing mistake.
Use margin when you're thinking about revenue and markup when you're setting a price from a known cost. The margin calculator shows both from the same inputs, so you see the difference before you set the price.
Loan-to-value (LTV)
LTV is the loan amount divided by the value of the asset securing it, as a percentage. A $180,000 mortgage on a $200,000 home is 90% LTV. Lenders read it as risk: the higher the LTV, the less owner equity there is to absorb a drop in value, which is why rates and mortgage insurance requirements often step up past 80%.
The LTV calculator converts between loan amount, value and ratio.
Debt service coverage ratio (DSCR)
DSCR is net operating income divided by total debt service (principal plus interest) over the same period. A DSCR of 1.25 means income covers the debt payment 1.25 times over. Below 1.0 the property doesn't earn enough to pay its own loan, and commercial and rental lenders usually want a comfortable cushion above 1.0.
The DSCR loan calculator works out the ratio from income and payment.
Capitalization rate (cap rate)
A cap rate is a property's net operating income divided by its price, as a percentage. That's the unleveraged yield, what you would earn paying cash, and it puts properties of different sizes on the same footing. A lower cap rate usually means a higher price for a given income, which the market tends to assign to assets it sees as safer or better located.
The cap rate calculator works it in either direction.
Break-even point
The break-even point is the sales volume at which total revenue equals total cost, so profit is zero. Below it you lose money; above it you make money. To find it, divide fixed costs by the contribution margin per unit, which is the price minus the variable cost of each unit.
The break-even calculator turns fixed cost, price and unit cost into that volume.
APY vs. interest rate
A nominal interest rate says nothing about how often interest is added. APY (annual percentage yield) folds the compounding in, so it's the figure that tells you what a year actually earns. A nominal 5% compounded monthly is an APY of 5.116%; compounded daily it's 5.127%. The gap widens as the rate rises.
So comparing one bank's nominal rate against another bank's APY compares two different things. US deposit accounts are required to advertise APY for this reason. Compare APY to APY. The CD calculator works in APY throughout.
CD early withdrawal penalty
A certificate of deposit locks money up for a fixed term in exchange for a set rate. Take it out early and the bank charges a penalty, usually stated as a number of months of interest: 90 days on a short CD, 180 on a longer one. If you withdraw before enough interest has accrued to cover it, the penalty can come out of your principal.
The CD calculator shows the penalty and what you actually walk away with.
HELOC
A home equity line of credit is a revolving loan secured by the equity in your home. During a draw period you borrow as needed up to a limit and pay interest only on what you use, then repay the balance over a later term. The rate is usually variable, tied to a benchmark plus a margin.
The HELOC calculator estimates payments and available credit.
Points (loan origination)
One point is 1% of the loan amount, charged up front and separate from the interest rate. Two points on a $300,000 loan is $6,000 due at closing. On a 30-year mortgage that cost spreads thin. On a 12-month bridge loan it doesn't, which is why points dominate the true cost of short-term borrowing.
A loan at 10% with 3 points, held for one year, costs roughly 13% in the year that matters. The hard money loan calculator keeps points separate from the rate so the total stays visible.
After-repair value (ARV)
ARV is the estimated market value of a property once the planned renovation is finished. Short-term and hard money lenders size loans as a percentage of ARV, commonly 65% to 75%, instead of as a percentage of what you're paying today.
That makes ARV the number the whole deal rests on, and it's an appraisal of a building that doesn't exist yet. An optimistic ARV produces a loan that looks conservative on paper and isn't. The hard money loan calculator takes it as an explicit input for that reason.
Final value fee
The commission a marketplace charges when an item sells. The trap is the base. On most marketplaces the fee applies to the total the buyer pays: item price plus shipping, and in many jurisdictions sales tax too. The item price alone is the wrong base.
A seller who computes 13% of a $40 item budgets $5.20 and gets charged closer to $6.50 once $10 of shipping is folded in. Budget the fee on the full buyer total. The eBay fee calculator applies it that way.
Payment processing fee
Card processing is priced as a percentage plus a fixed amount per transaction, and 2.9% + 30¢ is the common shape. The two parts behave very differently as the amount changes.
On a $100 charge the fee is $3.20, or 3.2%. On a $3 charge it's 39¢, or 13%. The fixed part is what makes micro-payments uneconomic, and it's the part flat-percentage estimates miss. If you sell low-priced items, that fixed 30¢ is the number to watch. The Stripe fee calculator shows the effective percentage next to the amount.
Stacked discount
Two discounts applied one after the other don't add up. Twenty percent off, then a further ten percent off, is 28% off, not 30%, because the second percentage applies to the already-reduced price.
The shortfall grows with the numbers: 50% then 50% is 75% off, not free. Retailers that advertise "extra 10% off sale prices" are describing this arithmetic accurately; the confusion is on the reading side. The discount calculator handles stacked discounts explicitly.
Exchange rate spread
The mid-market rate is the midpoint between what buyers and sellers are quoting, and it's the rate you see in a search result. The rate you actually get is worse, and the gap is the spread.
For consumer currency exchange the spread is usually the real cost, and the advertised "fee" is the smaller half. A service charging zero commission at a 3% spread costs more than one charging a flat fee at the mid-market rate. Ask for the rate you'll get, and don't stop at the fee. The currency converter has a mode for entering a spread so the two can be compared.
CPM (cost per mille)
CPM is the cost of one thousand impressions in advertising ("mille" is Latin for thousand). It prices reach, and says nothing about clicks or sales. It lets you compare the cost of showing an ad across campaigns of different sizes: total cost divided by impressions, times a thousand.
The CPM calculator converts between cost, impressions and CPM.
Net promoter score (NPS)
NPS measures customer loyalty from a single question: how likely are you to recommend us, from 0 to 10? Respondents scoring 9 or 10 are promoters, 7 or 8 are passives, and 0 to 6 are detractors. The score is the percentage of promoters minus the percentage of detractors, which gives a number from −100 to +100. Passives count toward the total but not the score.
The NPS calculator works out the score from response counts.
Work and pay
PTO accrual
Paid time off often builds up gradually instead of arriving in one lump each year. The accrual rate is how much PTO you earn per unit of work, such as a set number of hours per pay period or per hour worked. Multiply the rate by time worked to get the balance at any date.
The PTO accrual calculator projects the balance forward from a rate and a starting point.
Overtime and time and a half
In the United States, non-exempt employees earn overtime for hours worked beyond 40 in a week, paid at "time and a half", or 1.5 times the regular hourly rate. Some situations carry double time. The premium applies only to the extra hours, not to the whole week.
The overtime calculator splits regular and overtime pay from hours and rate.
Regular rate of pay
Under US federal law, the base for overtime isn't simply the stated hourly wage. The regular rate is total straight-time earnings for the week divided by hours worked, and it must include non-discretionary bonuses, shift differentials and commissions.
Someone paid $20 an hour plus a $100 production bonus over 50 hours has a regular rate of $22, so the overtime premium is owed on $22. Using the posted wage instead is one of the most common wage-and-hour errors. The overtime calculator takes the regular rate as its base.
Full-time equivalent (FTE)
FTE expresses staffing in units of one full-time schedule instead of in people. Against a 40-hour standard, two employees working 20 hours each are 1.0 FTE, not 2. That's the point: it makes a part-time team and a full-time team comparable.
The standard week is a choice, and it changes the answer. The same team is a different FTE count against 35, 37.5 or 40 hours, so the denominator has to travel with the number. The FTE calculator takes it as an input.
Severance pay
Severance is compensation offered when employment ends, often expressed as a number of weeks of pay per year of service. Most of the United States doesn't require it by law; when it is offered, the formula and any conditions come from company policy or a negotiated agreement.
The severance calculator estimates a package from tenure and salary.
Raise vs. cost-of-living adjustment
A cost-of-living adjustment is meant to hold purchasing power steady against inflation. A merit raise is meant to increase it. A 3% increase in a year of 3% inflation is the first wearing the clothes of the second: the same money, renamed.
The figure that answers "am I better off?" is the increase minus inflation over the same period, and it can be negative in a year that felt like a raise. The salary increase calculator shows the nominal and the real change together.
Construction and home
R-value
R-value measures a material's resistance to heat flow: the higher the number, the better it insulates. It depends on the material and its thickness together, so a thin sheet of rigid foam can out-insulate a thicker fiberglass batt. Recommended R-values for walls, attics and floors vary by climate zone.
The R-value calculator helps you size insulation to a target.
U-factor
U-factor measures how readily heat passes through an assembly. It's the reciprocal of R-value. Lower is better, the opposite of the convention people carry over from insulation, and that reversal causes real mistakes when comparing a window against a wall.
Windows are rated in U-factor because a window is an assembly of glass, gas fill, spacer and frame, not a single material. A U-factor of 0.30 corresponds to about R-3.3. The window replacement calculator works in the ratings the industry actually quotes.
CFM (cubic feet per minute)
CFM measures airflow: the volume of air a fan, vent or HVAC system moves each minute. Sizing ventilation for a room means matching CFM to the room's volume and to the number of air changes per hour the use calls for. A bathroom fan and a kitchen hood have very different targets.
The CFM calculator sizes airflow to a room.
Cubic yard
Concrete and bulk materials are sold by the cubic yard, a cube three feet on each side, or 27 cubic feet. To estimate a pour, convert the slab or footing dimensions to cubic yards, then add a small overage for spillage and uneven subgrade so you don't come up short mid-pour.
The concrete calculator converts dimensions to yards with an overage allowance.
Roofing square
A roofing square is 100 square feet. Materials and labor are both quoted in squares, so a 2,400 square foot roof is 24 squares before any allowance for waste.
The trap is measuring the building instead of the roof. A pitched roof always has more surface than the footprint under it. A 6:12 pitch adds about 12% and a 12:12 pitch about 41%, so a footprint measurement under-orders material every time. The roofing calculator applies the pitch multiplier.
Rise and run
Rise is the vertical height of one step; run is the horizontal depth of the tread. Total rise divided by the number of steps gives the individual rise. Building codes cap it, commonly around 7¾ inches, and set a minimum run.
Codes also require the steps in a flight to be uniform within about ⅜ inch, because an inconsistent step is what people trip on. That constraint, more than the total height, is usually what fixes the step count. The stair calculator solves for a legal, uniform flight.
Spread rate (paint coverage)
Spread rate is the area one unit of paint covers at the intended film thickness, typically 350 to 400 square feet per US gallon on primed, smooth drywall.
Real surfaces take more. Bare drywall, masonry and heavy texture can cut the rate by a third or more, and a color change usually needs two coats whatever the can claims. Ordering from the label figure for an unprimed wall is the standard way to run out mid-job. The paint calculator takes surface and coats as inputs.
On-center spacing
Framing spacing is measured center to center of the members, not from the edge of one to the edge of the next. "16 inches on center" means the centers sit 16 inches apart, leaving about 14½ inches of clear gap between 2× lumber.
The distinction matters at the ends of a run and when counting members. A 16-foot wall at 16 in OC takes 13 studs, not 12, because both ends get one. The deck cost calculator and the fence calculator both count members this way.
Ampacity and wire gauge (AWG)
Ampacity is the current a conductor can carry continuously without exceeding its temperature rating. American Wire Gauge runs backwards: a smaller AWG number is a thicker wire, so 10 AWG carries considerably more than 14 AWG.
Ampacity doesn't always size the wire. Over a long run, voltage drop becomes the binding constraint and forces a thicker conductor than the current alone would need. A circuit that is legal on ampacity can still deliver too little voltage at the far end. The wire size calculator checks both.
Rebar size numbering
US rebar sizes are given in eighths of an inch of nominal diameter. A #4 bar is 4/8, half an inch. A #5 is 5/8, and a #8 is a full inch. The number is a fraction with the denominator left off.
Metric designations name the diameter in millimeters instead, so a 10M bar and a #3 bar are close but not identical. Mixing the two conventions on one drawing produces a real error. The rebar calculator works in the US numbering.
Waste factor
The extra material ordered beyond the measured area, to cover cuts, breakage and mistakes. Ten percent is the usual starting point for tile in a simple rectangular room.
Layout drives it more than area does. A diagonal or herringbone pattern wastes far more at the perimeter and commonly needs 15 to 20%, and a room with many jogs and thresholds needs more again. Order a few extra boxes from the same dye lot too: they cover future repairs, which a later order won't match. The tile calculator takes the factor as an input.
Asphalt tonnage
Asphalt is sold by weight while a driveway is measured by volume, so every estimate goes through a density figure, around 145 pounds per cubic foot for typical compacted hot mix.
Density varies with the mix and with how thoroughly it's compacted, and the loose material laid down takes up noticeably more volume than the finished depth. An estimate that ignores compaction under-orders. The asphalt calculator converts area and depth to tons at a stated density.
Drywall sheet coverage
A 4×8 sheet covers 32 square feet, a 4×10 covers 40, and a 4×12 covers 48. Divide wall area by sheet area for the raw count.
Longer sheets are usually the better order even though they're harder to handle. They cross more studs, which means fewer butt joints, and butt joints are the ones that show. Deducting openings only helps below roughly a full sheet of area, since the offcuts around a small window rarely go anywhere useful. The drywall calculator counts sheets, screws and compound together.
Freight class
In US less-than-truckload shipping, freight class is a standardized code (from 50 to 500) that sets how a shipment is priced. It comes mainly from density (weight per cubic foot), along with handling, stowability and liability. A dense, sturdy pallet lands in a low class and ships cheaper per pound than a light, bulky one.
The freight class calculator works out the class from dimensions and weight.
A note on these definitions
Each entry is written to make a tool's output readable. None of it replaces professional judgment. Where money or a structure is involved, treat the number as a starting point and confirm it with someone who knows your specific situation.
Missing a term? Tell us. The list is meant to grow, and a term someone had to look up elsewhere is exactly the kind that belongs here.
Frequently asked questions
What is the difference between margin and markup?
Margin is profit as a percentage of the selling price; markup is profit as a percentage of the cost. A product bought for $80 and sold for $100 carries a 20% margin ($20 on $100) and a 25% markup ($20 on $80). People confuse the two all the time, and the gap widens as the percentage grows.
Is R-value the same as insulation thickness?
No. R-value measures resistance to heat flow. It depends on the material as well as the depth, so a thin sheet of rigid foam can carry a higher R-value than a thicker batt of fiberglass. Two inches of one material and two inches of another rarely share the same R-value.
Does a lower cap rate mean a better property?
Not by itself. A cap rate is net operating income divided by price, so a lower cap rate means a higher price relative to income, which the market often assigns to properties seen as safer or in stronger locations. Whether that's 'better' depends on the risk you're pricing. The number alone won't tell you.
Why is APY higher than the interest rate?
APY includes compounding and a nominal rate doesn't. A nominal 5% compounded monthly earns 5.116% over a year, because each month's interest starts earning interest of its own. The two figures aren't comparable, which is why US deposit accounts are required to advertise APY. Compare APY to APY.
Are these definitions financial or medical advice?
No. This glossary explains what each term means and how it's calculated, so the matching tool's output makes sense. It isn't advice. For a decision with money or a structure at stake, confirm with a professional who knows your situation.