Free tool
Enter an IPv4 address and a prefix length to get the subnet mask, network address, broadcast address, host range and address count, worked the way networking questions on IT certification exams expect.
Built for Security+ and networking exam prepThe number after the slash, as in /26.
Enter a valid IPv4 address and a prefix from 0 to 32.
Subnetting shows up in networking and security exams. Encodr turns the method into spaced-repetition practice so it holds until exam day.
Get started freeA prefix length such as /26 says how many of the 32 address bits are the network part. The
remaining bits are the host part, so the subnet holds 2^(32 - prefix) addresses. A /26
leaves 6 host bits, which is 64 addresses.
The network address is the first address in the block (all host bits 0) and the broadcast address is the last (all host bits 1). On ordinary subnets those two are not assignable to hosts, so the usable count is the total minus 2. Worked example: 192.168.10.77/26 sits in the block 192.168.10.64 to 192.168.10.127, with 62 usable hosts from .65 to .126.
Two edge cases: a /31 has two addresses and both are usable on point-to-point links (RFC 3021), and a /32 is a single host address. This tool applies those two special cases.
Related prep: the CompTIA Security+ course page (the course is in the works) and the Security+ vs Network+ vs A+ guide.
The well-known port numbers worth memorizing for CompTIA Security+ and networking exams, grouped by job, with tips for making them stick.
What each of the five SY0-701 domains covers, how much of the exam it is worth, and how to split your study time across them.
How CompTIA A+, Network+ and Security+ differ, what CompTIA recommends before Security+, and how to choose an order.
Log your practice tests - score, breakdown, conditions, date - and get a weighted prediction of your real MCAT score.
Open tool →Calculate your cumulative GPA and BCPM science GPA on the AMCAS 4.0 scale.
Open tool →Enter your exam date, hours needed, and difficulty to see how much less time targeted review actually takes.
Open tool →Enter passages completed and minutes elapsed to see your current pace and whether you are on track to finish the CARS section on time.
Open tool →See the Ebbinghaus forgetting curve for cramming vs. spaced review, and where each review session resets your retention.
Open tool →Enter a course, its credit hours, and how memorization-heavy it is to get a recommended daily and weekly study load.
Open tool →Enter your current grade, the final's weight, and your target grade to see the exact score you need on the final.
Open tool →Calculate your unweighted and weighted GPA (honors +0.5, AP/IB +1.0) side by side - not just pre-med, works for any transcript.
Open tool →Enter total questions and the passing percentage to see exactly how many you can miss and still pass.
Open tool →Enter deck size and your new-cards-per-day pace to see when first exposure finishes and your steady-state daily review load.
Open tool →Enter your grading categories and their weights to see your current overall grade, even with categories still outstanding.
Open tool →Convert instantly between letter grades, percentages, and 4.0-scale GPA points.
Open tool →Convert between metric and imperial units for length, mass, pressure/stress, torque, and volume flow rate - built for engineering coursework, not just everyday conversions.
Open tool →Enter two measurements with their uncertainties to see the propagated uncertainty in a sum, difference, product, or quotient.
Open tool →Enter a discount rate and a series of cash flows to get both the net present value and the internal rate of return.
Open tool →Enter fixed costs, price per unit, and variable cost per unit to see exactly how many units - and how much revenue - it takes to break even.
Open tool →Enter your participation, case write-up, project, and exam weights to see your current grade in a case-method business course.
Open tool →Score your own work against a weighted studio rubric - concept, execution, craft, presentation, and reflection - before a critique or portfolio review.
Open tool →Enter one source once and get correctly formatted citations in APA, MLA, and Chicago side by side, for books, websites, and journal articles.
Open tool →Enter total pages, days available, and how dense the reading is to see how many pages a night it actually takes to keep up.
Open tool →A free, no-signup Pomodoro timer with customizable work and break lengths and a running count of completed sessions.
Open tool →Enter your total credit hours this term to see the weekly study time the standard "2-3 hours per credit hour" rule recommends.
Open tool →Enter your current GPA, credits earned, target GPA, and credits this semester to see the exact GPA you need this term.
Open tool →See whether a property policy met its coinsurance requirement and exactly what it pays on a loss - built for P&C license exam prep.
Open tool →Split a medical bill between you and the plan through the deductible, coinsurance, copay, and out-of-pocket maximum, step by step.
Open tool →Calculate days supply for tablets, oral liquids, and insulin, rounded down to whole days - built for pharmacy technician exam prep.
Open tool →Mix a higher and a lower strength to make a desired strength and quantity - get the parts and the amount of each.
Open tool →Calculate IV flow rate in mL/hr, drip rate in gtt/min for any drop factor, and infusion time, with the working shown.
Open tool →Split a real estate commission between the listing and buyer brokerages, then between each broker and agent, with the math shown.
Open tool →Prorate annual property taxes at closing on a 360 or 365-day year, with the day count and the seller's share credited to the buyer.
Open tool →Practice the standard phlebotomy order of draw: tap random sets of collection tubes into the correct sequence and see where you slipped.
Open tool →Look up a blood collection tube by color, additive or test, with its typical use and order-of-draw step.
Open tool →Current yield, an approximate yield to maturity and tax-equivalent yield with the formulas shown - built for Series 7 exam prep.
Open tool →Profit or loss, breakeven, maximum gain and maximum loss for a long or short call or put at expiration - built for FINRA SIE exam prep.
Open tool →Public offering price, shares bought, front-end load, your own breakpoint schedule and a back-end CDSC by year - built for FINRA SIE exam prep.
Open tool →Debit or credit balance, equity, maintenance call and the trigger price for a long or short margin position - built for FINRA SIE exam prep.
Open tool →Add eye, verbal and motor responses into a Glasgow Coma Scale total. A study aid for EMS students, not for patient care.
Open tool →