About Per%Sense
Every financial calculation you can imagine — since the 1980s.
Heritage
Forty years ago, PerSense for DOS was hailed as the world's #1 financial calculation software. It offered features and computational power that have never been duplicated, and thousands of users continued to prefer it decades after its release — many running the original DOS program in emulators long after the operating system itself had disappeared.
An earlier version of PerSense was sold by Timeslips Corp under the name PercentEdge. A Windows edition followed, keeping the same solid, reliable mathematical code. This web edition is the next chapter: the complete DOS computational engine — including capabilities that never made it into the Windows version — faithfully ported and made available in the browser.
PerSense is a registered trademark. The original software and its documentation live at persense.org, maintained by its author, Josh Mitteldorf.
The Fill-in-the-Blank Interface
Fill in what you know — Per%Sense senses what you don't know, and completes the picture.
All three worksheets are organized as column-and-row spreadsheets with pre-programmed formulas. What makes Per%Sense special is that the inverse of every formula is available in the same template, with a smart algorithm that notes from context what is missing and calls on the correct formula to calculate it.
Leave any cell blank; when enough information has been entered to determine that value, Per%Sense computes it on the next Calculate. On the Amortization screen, fill in the loan amount, dates, and interest rate to compute the payment — or leave the rate blank and fill in the payment instead, and the rate is computed. Leave the duration blank and it is solved. Fill in everything and ask for the terminal balloon that completes the loan. This intelligent flexibility is the feature that gives Per%Sense its power.
What Per%Sense Does
Loan Amortizations
- Simple monthly loans, and complex structured loans combining options to your spec
- Multiple balloon payments, delayed principal repayment, skipped payments
- ARMs and variable rates
- Monthly, quarterly, weekly, and bi-weekly payment schedules
- APR calculation for loans with arbitrary structure
- Payment from rate, or rate from payment — either direction
Present Values
- Annuities, structured legal settlements, and any structured payout
- Valuation of legal claims for damages
- Retirement planning, investment analysis, and IRR
- Comparison of business options: which deal is best?
- Valuation with an interest rate that changes over time
- Life-contingent payments, actuarial present values, and death benefits
Loan Comparison
- Compare loans of different duration and different interest rate
- Evaluate the tradeoff between a low interest rate and a low APR
- Points, fees, and balloons folded into a true APR comparison
- Fixed interest or ARM
Accuracy and Computational Standards
Loan interest has its own world of rules, and Per%Sense can be configured to emulate all the major and minor standards that are commonly applied:
- 360- or 365-day basis (365/360 also supported)
- Points applied at settlement; prepaid interest at settlement, or a partial month's interest amortized over the life of the loan
- Monthly, weekly, or daily rates — also quarterly, biweekly, bimonthly, semi-monthly, and semi-annual payments
- Canadian rates and bond yields
- Variable rate loans
- American rule (simple interest) and Rule of 78
- Interest in advance or arrears
Computational integrity and absolute accuracy are the first concern. Major legal and accounting firms have relied on results from Per%Sense. You can, too.
What Reviewers Said
“If software pricing is based on usefulness, this program is drastically underpriced… Overall, I give PerSense a hefty A-Plus on all counts.”
— Walter Salm, syndicated column
“It certainly makes financial calculations easy. It almost makes them fun.”
— L. R. Shannon, The New York Times
“Problems involving the time value of money are often the hardest to calculate. PerSense… handles these numbers with a mix of comprehensiveness and simplicity that should please both the professionals and home users.”
— PC Resource
“PerSense is a clear winner.”
— Barry D. Bayer, Benjamin H. Cohen & Mark J. Welch, Law Office Technology Review
The Web Edition
This application is a faithful port of the original Per%Sense computational engine. The DOS version is treated as the authority for every financial calculation: rounding conventions, day-count rules, and solver behavior are reproduced exactly, and the port is continuously verified against reference output generated from the original Pascal source.
It also restores capabilities that the DOS version had but the Windows edition never received — notably the actuarial calculations that combine life expectancy with present value: life-contingent annuity valuation, actuarial present values, and Payment-on-Death (life insurance) benefits, for one or two lives.